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).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 !