[xj40] Does higher speed cause that much more stress on my XJ40?

Rememeber a H rated tire is good for 130MPH a V-rated tire is good for up 149MPH. That is not a such a drastic difference to be noted by anyone driving around at 70MPH or less.

Now if your talking about moving from V to S(112MPH). that might be significant.

From: Jay tigrr01@longlines.com
Date: 2006/01/12 Thu AM 10:54:22 EST
To: @David_Boarder
CC: Norman Watkins norman@norman-watkins.fsnet.co.uk, xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my XJ40?

Dave,

You should not be fixated in the speed rating being all there is to it.
There are many design factors in a tire, every tire and speed is only
one of them. On V rated tires the other factors are also accordingly
better than they would be on an H rated tire.

The big problem with using an H rated tire on a car suspensions designed
for V rated tires should have V rated tires or better, not only for
speed but because the V tuned suspension put more stress and produce
more heat in an H rated tire under all conditions from 0 to 100 mph than
it will for the V rated tire on the same car.

The speed rating is directly related to amount of heat the tire can
handle or vice versa the amount of heat a given type of tire will
generate under a given load. Naturally the belts and belt strength are
higher on the V rated tire, the side walls thicker to take the higher
side load thrust generated by the V tuned suspension and the rubber
compound and belt pattern designed to produce less heat for any given
speed.

Its false economy to put an H rated tire on your Jaguar. It wont last
as long as it would on car with an H rated suspension [assuming similar
weight and loading] because the H rated tire will develop more heat
under all speeds on the V rated suspension. Heat causes the rubber to
harden which reduces the stopping and cornering traction. Heat causes
the belts to delaminate over time. So putting more heat on the H rated
tire than it was desinged to take regardless of speed is going to make
it not only perform worse it will deteriorate faster and have less
stopping power in general and in particular less on wet roads.

Not to mention that if you drive it 80-90 mph as most people do around
my part of the country on the interstate highways here you will find
belts snapping fairly quickly on the H rated tire. Another factor is
the softness of the rubber in the tire when new. In particular the
Pirelli tires specified have a very soft rubber which is why most people
don’t get as good mileage as some of the H rated tires with harder
rubber used on cars with H rated suspensions. If you want to substitute
an H rated tire for a V rated tire because you are driving less than 100
mph all the time, you would need to find one with the same durometer
[softness rating of the rubber] as the V rated one or affect you
stopping distance nd cornering ability in general and in particular on
wet or icy roads. Finding an H rated tire with that soft a rubber may
be hard to do as they generally all have much harder rubber so they can
give you that 60,000 mile tread wear guarantee to go with the $65
bargain price.

Jay 90 VDP Majestic [Pirelli P4000 ST W rated for 189 mph BTW they only
cost about $10 ea. more than the cheapest H rated tire I could find at
the tire shop]

PS Why anyone would sacrifice stopping distance and handing on wet roads
to save $40 on a set tires is a mystery to me, never mind the risk the H
rated tires already hard rubber will harden much more rapidly on a V
rates suspension designed to put more stress on the tires than an H
rated one would. Forget the fact that the specified tire give a
smoother more comfortable ride which is what people by a luxury car like
a Jaguar for.

@David_Boarder wrote:

Limited by what? The CPU or the Ocean?
Does that mean all your cars that can do more than 100MPH must have V-rated tires?

From: Norman Watkins norman@norman-watkins.fsnet.co.uk
Date: 2006/01/11 Wed AM 11:57:10 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my XJ40?

Dave

Cars here that are limiteed are limiteed to 155 mph!

NW

Dave wrote:

Most of the cars in North America are running on less than V-rated
tires. Most of those cars are likely capable of speeds above 100MPH
(many modern cars are CPU speed limited for liability reasons).

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In reply to a message from AttyDallas sent Thu 12 Jan 2006:

Paul,

I’ve seen some of those biker groups - all leather and
tatoos. Who’s going to argue with them!!! :-)–
The original message included these comments:

btw, re: Phil’s comment on motorcycle helmets, I’m still stunned
that Texas repealed our helmet law a few years ago. I guess the
legislature was pressured into it by biker groups. Very strange


Bryan N, '91 Sovereign 4.0 L, (RHD)
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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Paul/Jay/Dave/Bryan et al

This is a veritable ‘can of worms’ I have opened isn’t it ?
I hope this discussion , if nothing else makes the average forum
lister/Jaguar owner at least give some more thought into his reasoning
before buying his tyres .
I think all that have contributed have made a very clear statement as to
where they stand in the matter.
I for one do not skimp on any issue that I believe to be safety related.
Brakes
Suspension
Tyres.
These are the main components that keep you on the road and hopefully in a
straight line whether you are doing 30mph or 130mph

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: “AttyDallas” attydallas2@aol.com
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?
Date: Thu, 12 Jan 2006 17:34:59 +0100

In reply to a message from wcmaness sent Thu 12 Jan 2006:

very good point to bring up, ‘‘WC’’ … Our AOL News had an article
on just this topic earlier last year. It showed how to find and de-
code the manufacture date (month and year) off your sidewalls and
the importance of not buying a tire that is more than two years old
(I believe that was the benchmark, it might be a year or two
longer, though) … Sometimes tires will sit in a warehouse or on a
shelf for several years before being sold, esp. the V-rated
ones … Looking back now I wonder if the Mickey V that ‘‘unraveled’’
on me that fateful day on the service road was an ‘‘oldie’’ … Old
tires are a major safety issue and a possible disaster just waiting
to happen, yet the general public is mostly unaware of this hazard
(I know I was until I read the article) … I wonder if we should
pass some laws making it unlawful to see tires past a certain
expiration date (or at least as ‘‘new’’ tires) …

btw, re: Phil’s comment on motorcycle helmets, I’m still stunned
that Texas repealed our helmet law a few years ago. I guess the
legislature was pressured into it by biker groups. Very strange
for a state which has such a strict (and strictly enforced)
seatbelt law!

The original message included these comments:

drivers. There you have it. Heck - tires even have an
expiration date on them now (good for those who store cars &
don’t realize the little used rubber has lost its integrity
but still looks good).


&:-)) Paul '88 XJ6 VDP 130k & '88 XJ6 VDP 180k
Garland, Texas, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

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Dave

The specified tire for the 1990 MY is a 205/70 VR15 not 215/65-VR15
though I believe the alternate winter tire was specified at 215/65 VR
15. To my recollection the 86-89 cars came with a 205/70 VR 15
specification.

I paid $105 plus tax each to have 4 Pirelli P4000 Super Touring W rated
tires installed and balanced with new stems and including the disposal
charge for the old tires.

Since you are quoting Canadian $$ not US$$ [exchange rate is = about
1.16:1.00 USD, it cost me about C$10 less for my Pirelli P4000 ST
205/70 WR 15 tires [C$672] than your VR rated ones. If you want to use
special tires like a 215/60 and special order a Pirelli you will pay
special prices and I note this is not a a fair comparison on your part
to pick a special order tire for comparison.

I checked speed ratings at the following site -
http://www.nhtsa.dot.gov/cars/rules/TireSafety/ridesonit/brochure.html

  • and found to my surprise that H rated tires are good for sustained
    speeds of 130 mph [surprise]. I also found my W rated tires were only
    rated for 168 mph not 186 mph as the tire catalog said. However there
    was an asterisk stating that for tires rated over 149 mph they often use
    ZR but for tires over 186 mph rated [Y is 186 mph] they always use ZR
    which may be the reason for the error in the tire manufacturers
    catalog. S rated tires are rated for 112 mph and T rated tires for 118
    mph. So for a similar quality Michelin T rated tire you will pay more
    than I did for my Pirelli P4000 ST W rated tire based on the on line
    prices quoted for the Michelin below. Also the same site had a Goodyear
    Assurance T rated for $102 each unmounted, unbalanced and without new
    stems or disposal charge for the old tire. So based on the National
    Tire Safety Institute information at the site above, an H rated tire is
    good for 130 mph speed rating. But again, speed rating is just one part
    of the tire spec. None of the tire shops had any good buys on an H
    rated tire.

I checked a good grade of less than V or W rated tire [S or T] and found
Michelin HydroEdge
http://www.discounttiredirect.com/direct/findTireDetail.do?sw=false&cs=205&pc=34344&rd=15&ar=70
P205/70R-15 95T BSW @ $102USD each unmounted at an on line shop.
That’s actually more than the W rated Pirelli P4000 ST? Its a T rated
tire. I also found a Michelin Symmetry GNX
http://www.discounttiredirect.com/direct/findTireDetail.do?sw=false&cs=205&pc=35781&rd=15&ar=70
P205/70R-15 95S WW [S rated] for $95 USD which is about the same price
mounted as my Pirelli P4000 ST W rated tire. Using these two quality S
and T rated tires doesn’t save any money over the W rated tire. Sure
you can buy cheap and by cheap I mean cheap in all way including life
and quality tires for $58 unmounted which would come to about $80
mounted balanced with new stems and disposal charge for the old tire.
That would be substituting cheap junk tire to save $25 USD per tire. I
wouldn’t use those tires on my Jeep Grand Cherokee which as a speed
governor set to keep it below 95 mph due to the 4 wd.

You can buy a cheaper tire such as a Yokohama Avid P205/70R-15 95S B [S rated] which also has an A traction rating for $57 but it only has a
tread wear rating of 620 verses the 800 on the Michelin. Meaning you
get what you pay for in an S rated tire. The Yokohama will wear out
faster than the Michelin not to mention the Michelin Hydroedge supposed
superior wet road design tread. Interesting enough the Pirelli P4000
Super Touring is rated as a Z by one tire site they also noted they only
had one left in stock and it was selling for $111 [Mavis Tires] The
Surprising fact was the Pirelli also has an Traction rating but it has a
320 tread wear rating. The comparable Michelin MXV4 205/70VR15 was
selling for $119 and had a traction rating of A and Tread Wear of 400.

It seems of all the tires specified for the XJ6 1990 XJ40 the tread
wear is much lower than many of the S nd T rated tires. The softer
rubber scrubs off in the corners and I suspect the suspension is
designed to have a tire that slides a bit as the rubber scrubs off.

However, it you take a Yokohama Avid 205/70SR15 $57 tire with a
traction rating of A and a tread wear of 620, and put it on the Jaguar
and drive it like a Jaguar you will without doubt find out that it does
not have a tread wear of 620 when misapplied.

So its far from a Speed Rating thing when it comes to tires

Jay 1990 XJ6 Vanden Plas Majestic

PS the only H rated tire I came up with was made by Pirelli and cost
more than their Z rated tire?
Another thing I learned was the Pirelli P4000 ST is that its an all
season tire. I did not know that.

dboarder@sympatico.ca wrote:

Its hardly a drop in the bucket. It depends a lot on where you live and how much you drive.

I was quoted by a Canadian Tire chain.

The spec’d tire Pirelli 225/65-VR15 $400each = $1600.00 (special order)
What I have on my car Yokohama 215/65-VR15 $178 each = $712.00
Just an estimate but I am sure a good none V-rated tire would be less than $100 = $400.00

Now my Jaguar is in storage during the winter months but with the V-rated tires they only last about 2 seasons. During the winter months I run a Ford Taurus.

If I wanted to use the “correct” tire for my car the difference versus a good H rated tire is $1200 over a 2 year period. I compromised and used different V-rated tire. That cost difference is probably significant more for someone using the H rated tires because in my experience they tend to have a longer life.

My point is that I am not going to get all hot and bothered if someone decides that a good H-rated tire will serve their needs when their needs are dictated by a 55-70mph speed limit which they intend to adhere to. Not all people who buy these cars are looking to push them to their limits. Often they are looking for a comfortable ride with some elegance. The reality of the situation is that often because of their low value these cars are often bought by people who especially rich. After all thats one reason this list exists.

I am sure someone in the US will point out how the tires can be bought much cheaper off some place like tirerack.com. However by the time I include the exchange rate, shipping, duty, taxes and installation the pricing is not that far off.

From: “Daniel Arsenault” arsenaultd@earthlink.net
Date: 2006/01/11 Wed PM 12:09:55 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my XJ40?

I have to say, I don’t understand the big debate of using S versus V or Z
rated tires. The cost difference in general is a drop in the bucket compared
to the peace of mind the higher end tires provide with better quality
construction. The performance advantages of a high end, high speed rated
tire are everything we are looking for , for our special cars. These are not
Hondas or Chevys.

I am one who feels if you are looking to cheap out on the quality tire you
place on your car, the Jaguar is not the right car for you. A set of very
very good tires runs what, maybe $500, versus a set of mediocre tires at
$350? What in the world would anyone be thinking to cheat a little, and go S
rated just to save a measly two or three tanks of gas.

Seems silly to me, there should be no debate. Its Z rated for me all the
way. The performance and handling alone are worth the extra expense.

Daniel
1994 XJ12
1995 XJS 4.0

----- Original Message -----
From: “Norman Watkins” norman@norman-watkins.fsnet.co.uk
To: xj40@jag-lovers.org
Sent: Wednesday, January 11, 2006 8:57 AM
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?

Dave

Cars here that are limiteed are limiteed to 155 mph!

NW

Dave wrote:

Most of the cars in North America are running on less than V-rated
tires. Most of those cars are likely capable of speeds above 100MPH
(many modern cars are CPU speed limited for liability reasons).

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting

services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

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More on Tread Wear at this site
http://www.tirerack.com/tires/Spec.jsp?make=Pirelli&model=P6000+Sport+Veloce
UTWG is the uniform tread wear grade and on further research it develops
this is a relative number used to marketing advantage since it is
extrapolated data and fairly useless between brands though it has some
relationship between tires of the same brand.

Another interesting fact popped up while trying to find an alternate
for the very good P4000 ST Z W rated tired depending on the site one
visits [it appears to be coming up in short supply at a lot of shops]
was that the P6000 Veloce does not come in the 205/70 R 15 size. It
does come in the 215/65 HR 15 size though [H rated to 130 mph] and has a
traction rating of AA which is the highest rating according to national
tire standards. The P6000 Veloce also has a load rating of over 1500 lbs
which is in the top 90% or so of all the tires listed.

Surprisingly enough this tire has a price of $7 5USD each Since its an
H rated tire [130 mph] has the highest traction rating available and for
its wheel size about the highest load rating it would seem to be
ideally suited to the Jaguar XJ6 XJ40. No I don’t own stock in any of
these companies or have any other blah blah blah. What I can’t
understand is why you are paying C$178 when you can buy the P6000
Veloce H rated 130 mph 215/65 HR 15 for about $85 ea. at this site
http://www.tirerack.com/tires/Sizes.jsp?make=Pirelli&model=P6000+Sport+Veloce
That’s half what you quoted for the VR. The VR is 149 mph vs the 130
HR. I guess you have not been aware that the normal tires on most
production cars are S or T rated no H rated and the H is really only a
tad less than the V for speed rating. It seems that a little research
at this and other sites will turn up some valuable information on tires
for the XJ6
The P6 four season is also available in 215/65 HR 15 for about C$85 it
has a load rating of 1565 lbs and a AA traction rating which is the
highest there is. It has a 400 tread wear rating but that amy or may
not mean it wears faster based on comments on the use of this measure as
a marketing tool based on extrapolated data by some manufacturers. I
would be more interested in the AA traction and the fact that its rated
for 4 season use like P6000 Veloce
Sorry to say the P4000 ST seems to have been discontinued. Looks like I
will have to wait for all 4 tires to wear out and buy 4 new sneakers
[probably the P6. since it comes in a 205/65 VR 15 [C$90] and a 215/65
HR 15 [C$85] Note the 205/65 VR 15 these are half the price you
quoted. I could not find anyone who had the tire size you quoted in VR
Pirelli so it might be like the P4000 out of production. It looks like
Pirelli for 15 rims is going to be limited to the P6000 veloce 205/70 HR
15 or the P6 215/65 HR 15 or 205/65 VR 15 all about C$85 each This is
the site http://www.tirerack.com/tires/tirebran.jsp

Michelin has a Pilot Exalto in 215/65 HR 15 for about $90 USD [C$100].
It has the same rating AA traction and 400 tread wear as the Pirelli of
the same size just cost more.

Boy this is a bummer, if I want to keep my 15 diamond cut lattice wheels
that were one of the things that made the Majestic Majestic I better
buy a set of sneakers now before they go out of production entirely.
Michelin only list one that could be used and it was HR and there is
only one Pirelli in VR that would fit other than the stock of existing
P4000 ST’s that may be out there at a higher price.

Dunlop has an SP Sport A2 plus 215/65 HR15 for $61 USD [$C70] with AA
traction and 460 tread wear guide. And an SP Sport 4000 205/65 VR15 for
$81 USD with AA traction and only a 240 tread wear guide. Pretty slim
pickings for 205/70 VR 15 or better tires

Yokohama has an H4S Avid 215/65 HR15 for $69 USD [C$78] with a AA
traction and 500 tread wear guide. Looks like finding a V rated or
better tire for the 205/70 15 wheel is going to be impossible soon.

Does anyone know what other range of size tires could be safely used
with the 205/70 15" wheel?

Jay 90 VDP Majestic

dboarder@sympatico.ca wrote:

Its hardly a drop in the bucket. It depends a lot on where you live and how much you drive.

I was quoted by a Canadian Tire chain.

The spec’d tire Pirelli 225/65-VR15 $400each = $1600.00 (special order)
What I have on my car Yokohama 215/65-VR15 $178 each = $712.00
Just an estimate but I am sure a good none V-rated tire would be less than $100 = $400.00

Now my Jaguar is in storage during the winter months but with the V-rated tires they only last about 2 seasons. During the winter months I run a Ford Taurus.

If I wanted to use the “correct” tire for my car the difference versus a good H rated tire is $1200 over a 2 year period. I compromised and used different V-rated tire. That cost difference is probably significant more for someone using the H rated tires because in my experience they tend to have a longer life.

My point is that I am not going to get all hot and bothered if someone decides that a good H-rated tire will serve their needs when their needs are dictated by a 55-70mph speed limit which they intend to adhere to. Not all people who buy these cars are looking to push them to their limits. Often they are looking for a comfortable ride with some elegance. The reality of the situation is that often because of their low value these cars are often bought by people who especially rich. After all thats one reason this list exists.

I am sure someone in the US will point out how the tires can be bought much cheaper off some place like tirerack.com. However by the time I include the exchange rate, shipping, duty, taxes and installation the pricing is not that far off.

From: “Daniel Arsenault” arsenaultd@earthlink.net
Date: 2006/01/11 Wed PM 12:09:55 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my XJ40?

I have to say, I don’t understand the big debate of using S versus V or Z
rated tires. The cost difference in general is a drop in the bucket compared
to the peace of mind the higher end tires provide with better quality
construction. The performance advantages of a high end, high speed rated
tire are everything we are looking for , for our special cars. These are not
Hondas or Chevys.

I am one who feels if you are looking to cheap out on the quality tire you
place on your car, the Jaguar is not the right car for you. A set of very
very good tires runs what, maybe $500, versus a set of mediocre tires at
$350? What in the world would anyone be thinking to cheat a little, and go S
rated just to save a measly two or three tanks of gas.

Seems silly to me, there should be no debate. Its Z rated for me all the
way. The performance and handling alone are worth the extra expense.

Daniel
1994 XJ12
1995 XJS 4.0

----- Original Message -----
From: “Norman Watkins” norman@norman-watkins.fsnet.co.uk
To: xj40@jag-lovers.org
Sent: Wednesday, January 11, 2006 8:57 AM
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?

Dave

Cars here that are limiteed are limiteed to 155 mph!

NW

Dave wrote:

Most of the cars in North America are running on less than V-rated
tires. Most of those cars are likely capable of speeds above 100MPH
(many modern cars are CPU speed limited for liability reasons).

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting

services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

To the best of my knowledge Germany does. So far as I know some states
like Massachusetts and Rhode Island have annual inspections and they do
check the tires to see if they are as specified or better.
Jay

Phil Parrington wrote:

Hi all
Here us an interesting quote from the vehicle Inspectors bulletin for
Australia
See
http://www.ipe.nt.gov.au/whatwedo/mvr/vehiclestandards/pdf/vib03-2003-02.pdf

It mentions there that the vehicle that is being inspected must be
wearing tyres that have ratings that are equal or better than those
specified by the manufacturer.

Mmmmm

According to the XJ40 3.6 owners handook in front of me the type/size is
220/65 VR 390

I understand that the USA did not have the metric rims but what about
any Australian owners ?
What is written in your owners handbook ?
I wonder how many other countries have similar legislation ??

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: dboarder@sympatico.ca
To: Norman Watkins norman@norman-watkins.fsnet.co.uk,
xj40@jag-lovers.org
Subject: Re: Re: [xj40] Does higher speed cause that much more stress
on my XJ40?
Date: Wed, 11 Jan 2006 14:17:17 -0500

Limited by what? The CPU or the Ocean?
Does that mean all your cars that can do more than 100MPH must have
V-rated tires?

From: Norman Watkins norman@norman-watkins.fsnet.co.uk
Date: 2006/01/11 Wed AM 11:57:10 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress
on my XJ40?

Dave

Cars here that are limiteed are limiteed to 155 mph!

NW

Dave wrote:

Most of the cars in North America are running on less than V-rated
tires. Most of those cars are likely capable of speeds above 100MPH
(many modern cars are CPU speed limited for liability reasons).

Visit the Jag Lovers homepage at http://www.jag-lovers.org for
exciting services and resources including Photo Albums, Event Diary /
Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for
exciting services and resources including Photo Albums, Event Diary /
Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for
exciting services and resources including Photo Albums, Event Diary /
Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Try this one its not a manufacturer either
http://www.nhtsa.dot.gov/cars/testing/ncap

AttyDallas wrote:

In reply to a message from dboarder@sympatico.ca sent Wed 11 Jan 2006:

Here! Here! Dave … (and note: this source is NOT a tire
manufacturer)

The original message included these comments:

http://www.autotirecarcare.com/guide/speed.html


&:-)) Paul '88 XJ6 VDP 130k & '88 XJ6 VDP 180k
Garland, Texas, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Actually if I want the Pirelli P4000E in 225/65ZR15 I can get it at
http://www.1010tires.com/tiresearch.asp?submit=yes for a Canadian price of $249 ($219US) each.

From: Jay tigrr01@longlines.com
Date: 2006/01/12 Thu PM 01:47:53 EST
To: @David_Boarder, xj40 xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my XJ40?

More on Tread Wear at this site
http://www.tirerack.com/tires/Spec.jsp?make=Pirelli&model=P6000+Sport+Veloce
UTWG is the uniform tread wear grade and on further research it develops
this is a relative number used to marketing advantage since it is
extrapolated data and fairly useless between brands though it has some
relationship between tires of the same brand.

Another interesting fact popped up while trying to find an alternate
for the very good P4000 ST Z W rated tired depending on the site one
visits [it appears to be coming up in short supply at a lot of shops]
was that the P6000 Veloce does not come in the 205/70 R 15 size. It
does come in the 215/65 HR 15 size though [H rated to 130 mph] and has a
traction rating of AA which is the highest rating according to national
tire standards. The P6000 Veloce also has a load rating of over 1500 lbs
which is in the top 90% or so of all the tires listed.

Surprisingly enough this tire has a price of $7 5USD each Since its an
H rated tire [130 mph] has the highest traction rating available and for
its wheel size about the highest load rating it would seem to be
ideally suited to the Jaguar XJ6 XJ40. No I don’t own stock in any of
these companies or have any other blah blah blah. What I can’t
understand is why you are paying C$178 when you can buy the P6000
Veloce H rated 130 mph 215/65 HR 15 for about $85 ea. at this site
http://www.tirerack.com/tires/Sizes.jsp?make=Pirelli&model=P6000+Sport+Veloce
That’s half what you quoted for the VR. The VR is 149 mph vs the 130
HR. I guess you have not been aware that the normal tires on most
production cars are S or T rated no H rated and the H is really only a
tad less than the V for speed rating. It seems that a little research
at this and other sites will turn up some valuable information on tires
for the XJ6
The P6 four season is also available in 215/65 HR 15 for about C$85 it
has a load rating of 1565 lbs and a AA traction rating which is the
highest there is. It has a 400 tread wear rating but that amy or may
not mean it wears faster based on comments on the use of this measure as
a marketing tool based on extrapolated data by some manufacturers. I
would be more interested in the AA traction and the fact that its rated
for 4 season use like P6000 Veloce
Sorry to say the P4000 ST seems to have been discontinued. Looks like I
will have to wait for all 4 tires to wear out and buy 4 new sneakers
[probably the P6. since it comes in a 205/65 VR 15 [C$90] and a 215/65
HR 15 [C$85] Note the 205/65 VR 15 these are half the price you
quoted. I could not find anyone who had the tire size you quoted in VR
Pirelli so it might be like the P4000 out of production. It looks like
Pirelli for 15 rims is going to be limited to the P6000 veloce 205/70 HR
15 or the P6 215/65 HR 15 or 205/65 VR 15 all about C$85 each This is
the site http://www.tirerack.com/tires/tirebran.jsp

Michelin has a Pilot Exalto in 215/65 HR 15 for about $90 USD [C$100].
It has the same rating AA traction and 400 tread wear as the Pirelli of
the same size just cost more.

Boy this is a bummer, if I want to keep my 15 diamond cut lattice wheels
that were one of the things that made the Majestic Majestic I better
buy a set of sneakers now before they go out of production entirely.
Michelin only list one that could be used and it was HR and there is
only one Pirelli in VR that would fit other than the stock of existing
P4000 ST’s that may be out there at a higher price.

Dunlop has an SP Sport A2 plus 215/65 HR15 for $61 USD [$C70] with AA
traction and 460 tread wear guide. And an SP Sport 4000 205/65 VR15 for
$81 USD with AA traction and only a 240 tread wear guide. Pretty slim
pickings for 205/70 VR 15 or better tires

Yokohama has an H4S Avid 215/65 HR15 for $69 USD [C$78] with a AA
traction and 500 tread wear guide. Looks like finding a V rated or
better tire for the 205/70 15 wheel is going to be impossible soon.

Does anyone know what other range of size tires could be safely used
with the 205/70 15" wheel?

Jay 90 VDP Majestic

@David_Boarder wrote:

Its hardly a drop in the bucket. It depends a lot on where you live and how much you drive.

I was quoted by a Canadian Tire chain.

The spec’d tire Pirelli 225/65-VR15 $400each = $1600.00 (special order)
What I have on my car Yokohama 215/65-VR15 $178 each = $712.00
Just an estimate but I am sure a good none V-rated tire would be less than $100 = $400.00

Now my Jaguar is in storage during the winter months but with the V-rated tires they only last about 2 seasons. During the winter months I run a Ford Taurus.

If I wanted to use the “correct” tire for my car the difference versus a good H rated tire is $1200 over a 2 year period. I compromised and used different V-rated tire. That cost difference is probably significant more for someone using the H rated tires because in my experience they tend to have a longer life.

My point is that I am not going to get all hot and bothered if someone decides that a good H-rated tire will serve their needs when their needs are dictated by a 55-70mph speed limit which they intend to adhere to. Not all people who buy these cars are looking to push them to their limits. Often they are looking for a comfortable ride with some elegance. The reality of the situation is that often because of their low value these cars are often bought by people who especially rich. After all thats one reason this list exists.

I am sure someone in the US will point out how the tires can be bought much cheaper off some place like tirerack.com. However by the time I include the exchange rate, shipping, duty, taxes and installation the pricing is not that far off.

From: “Daniel Arsenault” arsenaultd@earthlink.net
Date: 2006/01/11 Wed PM 12:09:55 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my XJ40?

I have to say, I don’t understand the big debate of using S versus V or Z
rated tires. The cost difference in general is a drop in the bucket compared
to the peace of mind the higher end tires provide with better quality
construction. The performance advantages of a high end, high speed rated
tire are everything we are looking for , for our special cars. These are not
Hondas or Chevys.

I am one who feels if you are looking to cheap out on the quality tire you
place on your car, the Jaguar is not the right car for you. A set of very
very good tires runs what, maybe $500, versus a set of mediocre tires at
$350? What in the world would anyone be thinking to cheat a little, and go S
rated just to save a measly two or three tanks of gas.

Seems silly to me, there should be no debate. Its Z rated for me all the
way. The performance and handling alone are worth the extra expense.

Daniel
1994 XJ12
1995 XJS 4.0

----- Original Message -----
From: “Norman Watkins” norman@norman-watkins.fsnet.co.uk
To: xj40@jag-lovers.org
Sent: Wednesday, January 11, 2006 8:57 AM
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?

Dave

Cars here that are limiteed are limiteed to 155 mph!

NW

Dave wrote:

Most of the cars in North America are running on less than V-rated
tires. Most of those cars are likely capable of speeds above 100MPH
(many modern cars are CPU speed limited for liability reasons).

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting

services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Jay

The plot thickens!
I think it fair to say however that sufficient evidence from good reliable
sources has been produced to suggest that ftting any tyre that is of lower
specification than the manufacturers recomendation is at the very least
unwise.

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: Jay tigrr01@longlines.com
To: Phil Parrington <@Phil-P>
CC: dboarder@sympatico.ca, xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?
Date: Thu, 12 Jan 2006 13:21:11 -0600

To the best of my knowledge Germany does. So far as I know some states
like Massachusetts and Rhode Island have annual inspections and they do
check the tires to see if they are as specified or better.
Jay

Phil Parrington wrote:

Hi all
Here us an interesting quote from the vehicle Inspectors bulletin for
Australia
See
http://www.ipe.nt.gov.au/whatwedo/mvr/vehiclestandards/pdf/vib03-2003-02.pdf

It mentions there that the vehicle that is being inspected must be wearing
tyres that have ratings that are equal or better than those specified by
the manufacturer.

Mmmmm

According to the XJ40 3.6 owners handook in front of me the type/size is
220/65 VR 390

I understand that the USA did not have the metric rims but what about any
Australian owners ?
What is written in your owners handbook ?
I wonder how many other countries have similar legislation ??

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: dboarder@sympatico.ca
To: Norman Watkins norman@norman-watkins.fsnet.co.uk,
xj40@jag-lovers.org
Subject: Re: Re: [xj40] Does higher speed cause that much more stress on
my XJ40?
Date: Wed, 11 Jan 2006 14:17:17 -0500

Limited by what? The CPU or the Ocean?
Does that mean all your cars that can do more than 100MPH must have
V-rated tires?

From: Norman Watkins norman@norman-watkins.fsnet.co.uk
Date: 2006/01/11 Wed AM 11:57:10 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on
my XJ40?

Dave

Cars here that are limiteed are limiteed to 155 mph!

NW

Dave wrote:

Most of the cars in North America are running on less than V-rated
tires. Most of those cars are likely capable of speeds above 100MPH
(many modern cars are CPU speed limited for liability reasons).

Visit the Jag Lovers homepage at http://www.jag-lovers.org for
exciting services and resources including Photo Albums, Event Diary /
Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Not really I think what we have seen is that there is a huge variation in driving requrements. The countries which are adement about not down rating the speed rating tend to be countries where they have roads with very high or none existent speed limits and it is an extremely logical law which requires that a vehicle be able to perform at its limit (because the law puts no restriction on its limit).

For countries where the max speed limits are very low and assuming its okay with the authorities anyone who wants to consider it needs to understand what all the ratings mean and ensure there choice is safe. To be getting a “cheap” tire should not be the primary reason.

For me I although I deviated from the recommended size I still stayed with the V-rating. My primary reason for that was the recommended size only had one option. I wanted better wet weather handling than that option offered. I have a 215/65R15 rather than a 225/65R15 with a slightly lower load rating. However its load rating is still meets the cars weight (given the axle weight in the owners manual. I also have a very significant design safety margin in that I am running a V-rated tire at speeds well under 100MPH.

One concern I have is that all tires are a compromise in some way. With the Jaguar it is a significant issue in that only one tire matches the spec in my manual. If I wanted a winter tire I would have little choice but to deviate from that. If I looked at H rated winter tires I would have much more choice in picking a tire which meets my requirements.

One item which would be really nice is if they came up with a better way of grading tires. After the issues with the Firestone tire failures they are introducing more stringent tire testing standards. We now also have the ratings for wear, traction and temperature. However unless you really care to do a lot of reading all that stuff can be quite confusing and misleading at times.

From: “Phil Parrington” pp221158@hotmail.com
Date: 2006/01/12 Thu PM 03:31:39 EST
To: tigrr01@longlines.com
CC: @David_Boarder, xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my XJ40?

Jay

The plot thickens!
I think it fair to say however that sufficient evidence from good reliable
sources has been produced to suggest that ftting any tyre that is of lower
specification than the manufacturers recomendation is at the very least
unwise.

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: Jay tigrr01@longlines.com
To: Phil Parrington pp221158@hotmail.com
CC: @David_Boarder, xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?
Date: Thu, 12 Jan 2006 13:21:11 -0600

To the best of my knowledge Germany does. So far as I know some states
like Massachusetts and Rhode Island have annual inspections and they do
check the tires to see if they are as specified or better.
Jay

Phil Parrington wrote:

Hi all
Here us an interesting quote from the vehicle Inspectors bulletin for
Australia
See
http://www.ipe.nt.gov.au/whatwedo/mvr/vehiclestandards/pdf/vib03-2003-02.pdf

It mentions there that the vehicle that is being inspected must be wearing
tyres that have ratings that are equal or better than those specified by
the manufacturer.

Mmmmm

According to the XJ40 3.6 owners handook in front of me the type/size is
220/65 VR 390

I understand that the USA did not have the metric rims but what about any
Australian owners ?
What is written in your owners handbook ?
I wonder how many other countries have similar legislation ??

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: <@David_Boarder>
To: Norman Watkins norman@norman-watkins.fsnet.co.uk,
xj40@jag-lovers.org
Subject: Re: Re: [xj40] Does higher speed cause that much more stress on
my XJ40?
Date: Wed, 11 Jan 2006 14:17:17 -0500

Limited by what? The CPU or the Ocean?
Does that mean all your cars that can do more than 100MPH must have
V-rated tires?

From: Norman Watkins norman@norman-watkins.fsnet.co.uk
Date: 2006/01/11 Wed AM 11:57:10 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on
my XJ40?

Dave

Cars here that are limiteed are limiteed to 155 mph!

NW

Dave wrote:

Most of the cars in North America are running on less than V-rated
tires. Most of those cars are likely capable of speeds above 100MPH
(many modern cars are CPU speed limited for liability reasons).

Visit the Jag Lovers homepage at http://www.jag-lovers.org for
exciting services and resources including Photo Albums, Event Diary /
Calendar, On Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from Phil Parrington sent Thu 12 Jan 2006:

I don’t see how you come to that conclusion. My reading of all
this is just the opposite.

Remember when Ford specified Firestone Wilderness tires for its
Explorers - that was unwise.–
The original message included these comments:

I think it fair to say however that sufficient evidence from good reliable
sources has been produced to suggest that ftting any tyre that is of lower
specification than the manufacturers recomendation is at the very least
unwise.


WCManess - 1991 XJ40/6 - Black/Grey - 4.0 liter
Arlington/Texas, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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In reply to a message from wcmaness sent Thu 12 Jan 2006:

I would be good to research the contraversy over Firestone
Wilderness tires on Explorers. As I understood it, Firestone
recommended 28 psig for the tires, but Ford recommended 24 psig
because the ‘car’ rode too ‘hard’ at the higher pressure.
Firestone took the hit for the roll-overs when Ford was at fault.
As I mentioned before, the rear gets ‘wiggly’ with too low a tire
pressure. With low pressure, the sidewall stiffness is not
adequate to allow for rapid maneuvers and hard cornering.
The last two times I needed tires for my pair of 88s, I went to the
salvage yards and bought almost new tires off wrecked cars. The
Pirelli 4000s I bought with 80% tread left cost $15 each. Breaking
yards have a devil’s time trying to dispose of tires, so they’re
happy to sell them cheap, and if your’re willing to wait, you can
most likely get exactly the tires you’re looking for.–
The original message included these comments:

Remember when Ford specified Firestone Wilderness tires for its
Explorers - that was unwise.


Pete 70 XKE (193K) 88 XJ6 (233K) 88 XJ6 (217K) 60 Mini
Severna park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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In reply to a message from Jaguarpete sent Thu 12 Jan 2006:

PSI was only part of the problem on the Explorer rollover/blowout
issue - but definitely an important one.

Who’d have thunk it - an auto manufacturer was wrong in its specs!–
WCManess - 1991 XJ40/6 - Black/Grey - 4.0 liter
Arlington/Texas, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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The FireStone thing seems to something where everything went wrong.

  • As you noted Ford set the tire pressure lower than FireStone wanted.
  • The Explorer is a heavy vehicle.
  • The rear suspension of the Explorer seems of poor design result in some
    very hammering (wheel hop) of the tire. I understand that Ford has a kit for
    New Zealand (which supposedly has bad roads) which includes new spec shocks
    because otherwise the tires disintegrate from the shock.
  • With the tire pressure already low owners (like many drivers) often had
    tires even below that already low spec.
  • there also seems to have been some issue with the quality control in some
    North American plants.
  • the truck like a top heavy vehicle so when there was a tire failure it
    often resulted in a roll over.

Often with specs each spec has some margin. In this case it looks like
everything was on low end of the margin and it added up to disaster.

I would be very concerned about using tires off a wreck unless I can be 100%
sure that it was not involved in the impact.----- Original Message -----
From: “Jaguarpete” jaguarpete@aol.com
To: xj40@jag-lovers.org
Sent: Thursday, January 12, 2006 5:40 PM
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?

In reply to a message from wcmaness sent Thu 12 Jan 2006:

I would be good to research the contraversy over Firestone
Wilderness tires on Explorers. As I understood it, Firestone
recommended 28 psig for the tires, but Ford recommended 24 psig
because the ‘car’ rode too ‘hard’ at the higher pressure.
Firestone took the hit for the roll-overs when Ford was at fault.
As I mentioned before, the rear gets ‘wiggly’ with too low a tire
pressure. With low pressure, the sidewall stiffness is not
adequate to allow for rapid maneuvers and hard cornering.
The last two times I needed tires for my pair of 88s, I went to the
salvage yards and bought almost new tires off wrecked cars. The
Pirelli 4000s I bought with 80% tread left cost $15 each. Breaking
yards have a devil’s time trying to dispose of tires, so they’re
happy to sell them cheap, and if your’re willing to wait, you can
most likely get exactly the tires you’re looking for.

The original message included these comments:

Remember when Ford specified Firestone Wilderness tires for its
Explorers - that was unwise.


Pete 70 XKE (193K) 88 XJ6 (233K) 88 XJ6 (217K) 60 Mini
Severna park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Dave
Totally agree with your comments and yet you advocate using tyres below
those that Jaguar stipulate in the owners handbook ??

Cake and eat it comes to mind :slight_smile:

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: “Dave” dboarder@sympatico.ca
To: xj40@jag-lovers.org, “Jaguarpete” jaguarpete@aol.com
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?
Date: Thu, 12 Jan 2006 18:31:00 -0500

The FireStone thing seems to something where everything went wrong.

  • As you noted Ford set the tire pressure lower than FireStone wanted.
  • The Explorer is a heavy vehicle.
  • The rear suspension of the Explorer seems of poor design result in some
    very hammering (wheel hop) of the tire. I understand that Ford has a kit
    for New Zealand (which supposedly has bad roads) which includes new spec
    shocks because otherwise the tires disintegrate from the shock.
  • With the tire pressure already low owners (like many drivers) often had
    tires even below that already low spec.
  • there also seems to have been some issue with the quality control in some
    North American plants.
  • the truck like a top heavy vehicle so when there was a tire failure it
    often resulted in a roll over.

Often with specs each spec has some margin. In this case it looks like
everything was on low end of the margin and it added up to disaster.

I would be very concerned about using tires off a wreck unless I can be
100% sure that it was not involved in the impact.

----- Original Message ----- From: “Jaguarpete” jaguarpete@aol.com
To: xj40@jag-lovers.org
Sent: Thursday, January 12, 2006 5:40 PM
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?

In reply to a message from wcmaness sent Thu 12 Jan 2006:

I would be good to research the contraversy over Firestone
Wilderness tires on Explorers. As I understood it, Firestone
recommended 28 psig for the tires, but Ford recommended 24 psig
because the ‘car’ rode too ‘hard’ at the higher pressure.
Firestone took the hit for the roll-overs when Ford was at fault.
As I mentioned before, the rear gets ‘wiggly’ with too low a tire
pressure. With low pressure, the sidewall stiffness is not
adequate to allow for rapid maneuvers and hard cornering.
The last two times I needed tires for my pair of 88s, I went to the
salvage yards and bought almost new tires off wrecked cars. The
Pirelli 4000s I bought with 80% tread left cost $15 each. Breaking
yards have a devil’s time trying to dispose of tires, so they’re
happy to sell them cheap, and if your’re willing to wait, you can
most likely get exactly the tires you’re looking for.

The original message included these comments:

Remember when Ford specified Firestone Wilderness tires for its
Explorers - that was unwise.


Pete 70 XKE (193K) 88 XJ6 (233K) 88 XJ6 (217K) 60 Mini
Severna park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

No the point is that the tires they were installing on the vehicle were
even worrying the manufacturer.
Then Ford insisted on lower the tire pressure by 4lbs below what the tire
manufacturer was recommending.

Basically if the owner followed the vehicles manufacturers advice for
tires he would have dangerous tires.
I wonder if an owner took the specs for the vehicle (ie weight, speed) and
shopped for a tire I wonder if he would come up with the same tire.
He is unlikely to come up with the same tire pressure. The load rating of a
tire is spec’d at the maximum tire pressure on the sidewall. Reducing the
tire pressure from that rating reducing the load rating of the tire. There
is a formulae for calculating the load rating of a tire at a lower pressure.

I don’t think anyone has admitted to fault in the Firestone situation so
its impossible to know what the real cause of the failure it.

Nor did I advocate using tires lower than the manufacturer recommends. I
simply state that if an owner wants to install tires of a lower rating and
drive the car according to that rating it does not concern me at all(and I
am taking speed rating). It just that everytime someone mentions doing
something like moving from a V rated tire to an H rated tire everyone jumps
all over him explainning that his tires are all going to explode.----- Original Message -----
From: “Phil Parrington” pp221158@hotmail.com
To: <@David_Boarder>; xj40@jag-lovers.org; jaguarpete@aol.com
Sent: Thursday, January 12, 2006 6:45 PM
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?

Dave
Totally agree with your comments and yet you advocate using tyres below
those that Jaguar stipulate in the owners handbook ??

Cake and eat it comes to mind :slight_smile:

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: “Dave” <@David_Boarder>
To: xj40@jag-lovers.org, “Jaguarpete” jaguarpete@aol.com
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?
Date: Thu, 12 Jan 2006 18:31:00 -0500

The FireStone thing seems to something where everything went wrong.

  • As you noted Ford set the tire pressure lower than FireStone wanted.
  • The Explorer is a heavy vehicle.
  • The rear suspension of the Explorer seems of poor design result in some
    very hammering (wheel hop) of the tire. I understand that Ford has a kit
    for New Zealand (which supposedly has bad roads) which includes new spec
    shocks because otherwise the tires disintegrate from the shock.
  • With the tire pressure already low owners (like many drivers) often had
    tires even below that already low spec.
  • there also seems to have been some issue with the quality control in
    some North American plants.
  • the truck like a top heavy vehicle so when there was a tire failure it
    often resulted in a roll over.

Often with specs each spec has some margin. In this case it looks like
everything was on low end of the margin and it added up to disaster.

I would be very concerned about using tires off a wreck unless I can be
100% sure that it was not involved in the impact.

----- Original Message ----- From: “Jaguarpete” jaguarpete@aol.com
To: xj40@jag-lovers.org
Sent: Thursday, January 12, 2006 5:40 PM
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?

In reply to a message from wcmaness sent Thu 12 Jan 2006:

I would be good to research the contraversy over Firestone
Wilderness tires on Explorers. As I understood it, Firestone
recommended 28 psig for the tires, but Ford recommended 24 psig
because the ‘car’ rode too ‘hard’ at the higher pressure.
Firestone took the hit for the roll-overs when Ford was at fault.
As I mentioned before, the rear gets ‘wiggly’ with too low a tire
pressure. With low pressure, the sidewall stiffness is not
adequate to allow for rapid maneuvers and hard cornering.
The last two times I needed tires for my pair of 88s, I went to the
salvage yards and bought almost new tires off wrecked cars. The
Pirelli 4000s I bought with 80% tread left cost $15 each. Breaking
yards have a devil’s time trying to dispose of tires, so they’re
happy to sell them cheap, and if your’re willing to wait, you can
most likely get exactly the tires you’re looking for.

The original message included these comments:

Remember when Ford specified Firestone Wilderness tires for its
Explorers - that was unwise.


Pete 70 XKE (193K) 88 XJ6 (233K) 88 XJ6 (217K) 60 Mini
Severna park, Maryland, United States
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services and resources including Photo Albums, Event Diary / Calendar, On
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One point that has not been mentioned:
In the XJ6 Handbook JJM 10 02 05/30 it states that “Tyres other than
those recommended ---- must be inflated to 3 bar or 44psi” - note MUST.
The tyres recommended are Pirellis P4000 ZR and P5 VR.
I trust all you people running non-recommended tyres are following this!

NW

Phil Parrington wrote:

Dave
Totally agree with your comments and yet you advocate using tyres
below those that Jaguar stipulate in the owners handbook ??

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Norman
I doubt that , afterall we now know that it doesn’t matter what is written
in the owners manual or the advice given on the Pirelli website.
Any info Jaguar or Pirelli give is purely on a self serving basis and can be
safely ignored in the quest to save money :-))

Phil

Find us at
http://www.xjjaguar.co.uk/
Call (+44) 01323 740471 ( 0900-1800 GMT ONLY)

From: Norman Watkins norman@norman-watkins.fsnet.co.uk
To: xj40@jag-lovers.org
Subject: Re: [xj40] Does higher speed cause that much more stress on my
XJ40?
Date: Fri, 13 Jan 2006 08:32:14 +0000

One point that has not been mentioned:
In the XJ6 Handbook JJM 10 02 05/30 it states that “Tyres other than those
recommended ---- must be inflated to 3 bar or 44psi” - note MUST.
The tyres recommended are Pirellis P4000 ZR and P5 VR.
I trust all you people running non-recommended tyres are following this!

NW

Phil Parrington wrote:

Dave
Totally agree with your comments and yet you advocate using tyres below
those that Jaguar stipulate in the owners handbook ??

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

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In reply to a message from Norman Watkins sent Fri 13 Jan 2006:

Norman,

That statement is also contained in the specifications
section of the Jaguar factory Service Manual - boy, it must
be like riding in a rail car at those pressures!

That section of the FSM makes interesting reading in other
respects. Apart from the obvious WARNING that cross-ply
tyres should not be fitted, it also states:-

  • It is preferable to replace worn tyres in complete sets.
  • No attempt must be made to interchange tyres from front to
    rear or vice-versa. (With that I agree and always follow).
  • Only tyres of IDENTICAL specification (to those listed in
    this section) MUST be fitted as replacements.
  • Tyres fitted to one axle must be from the same
    manufacturer and of the same type and tread pattern as tyres
    fitted to the other axle - i.e. treadpoatterns must not be
    intermixed

Another interesting note is that where they (Jaguar) define
the correct tyre pressures for the 225/55 x ZR16 tyres (as
fitted to my car as it happens) the reduced pressure
‘Comfort’ setting for all markets is shown as 28 psi F & R,
for all markets except Germany, the ‘Normal’ setting is 34
psi F & R, but for the German market (where some Autobahn
have no posted maximum speed restriction - ahhh, heaven!)
the ‘Normal’ setting is 43 psi F & R!!!

That should prolong this thread for a week or two whilst
opinions are batted back and forth!–
The original message included these comments:

In the XJ6 Handbook JJM 10 02 05/30 it states that ‘‘Tyres other than
those recommended ---- must be inflated to 3 bar or 44psi’’ - note MUST.
The tyres recommended are Pirellis P4000 ZR and P5 VR.
I trust all you people running non-recommended tyres are following this!


Bryan N, '91 Sovereign 4.0 L, (RHD)
Cambridge, United Kingdom
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In reply to a message from AttyDallas sent Tue 10 Jan 2006:

In my over 12 years of Jag ownership I have
never…ever…bought a V rated tire. In the USA we do NOT
have any place that you can legally go 120 MPH. If a shop
gives me the ‘‘We will not replace anything other than an OEM
V rated tire’’ , I walk. I guess in Europe there are
places that you can go over 120 MPH and from an OEM
standpoint Jaguar made the V rating standard to meet the
European speeds.

Once past Wyoming, in most States even if you find an
interstate that has enough open space to hit 125, there will
not be enough open distance before running into traffic that
your tires will over heat / stress enough to warrant V rating.
On the other hand it is their money and if they like
dropping the bills out the window…that is their choice.

Just MHO–
John S
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