[xj] tyres

…snip…

Without
exception, when I inquired about Pirelli P4000’s at 215/70 15 each tire shop
asked if I was driving a Jag. Evidently, the entire tire industry considers
these tires as tailor made for the XJ6.

The original OEM tyres were originally Dunlop and then they went to
Pirelli P600 ('81MY ? where’s Greg ?), the P4000 is the Pirelli
replacement for the 600, hence Jag owners look in their owners manual
and see the spec for what was originally on the car, ring up and ask for
it, and get told to get set of 4000’s. Nb Certain Beemers and Benzes
also used this size.

Secondly, both the Haynes Purchase and Restoration and Repair Manuals cite VR
rated Pirelli’s (either 205 or 215/70 15) as the recommended shoes for XJ6’s
in the US. It would seem that these cars were engineered to be shod with
these tires.

Any good quality 70 section tyre will do just fine provided it has the
right speed and load rating. The P4000 is quieter and cheaper than the
600 but doesn’t grip as well (IMHO), the Yokohama AVS someone mentioned
earlier got very good ratings in a number of a car mag tests. I was
planning on putting them on the XJ6 but they weren’t in stock so I went
to the Toyo’s (not the praxes though - I forget which) I was VERY
disappointed with them, one blew last week so I replaced both Toyos with
225/60 Bridgestone G Grids, which have proven themselves on the XJ12 as
excellent in the wet and quite grippy in the dry (and damn cheap) thanks
to Jan for the recommendation.

My inquiries into the necessity of tires rated for speeds up to
149 mph yielded valuable information concerning the structure in the sidewalls
of tires with such ratings also influencing handling and cornering
characteristics especially in vehicles possessing the weight of an XJ.

Which brings me to my final point (aren’t you glad?). Although wider wheels
and tires will give your cat a meaner look, any drastic deviation from Jag
engineered specs will place greater strain on the steering, suspension,
transmission, brakes as well as destroy the cloud like ride that the car is
famous for.

I’m sorry but I have to disagree with that as a generalisation, the 60
series on the S2 and S3 have not in way ruined the ride, and the stiffer
sidewalls dramatically improve the cornering capability.

Not to mention the tendency for wider tires to hydroplane on
those rainy days or nites.

Not if you buy good ones…I guess if you went 255 on the front you
might have a problem but you aren’t going to fit those in the wheel
wells anyway.

John–
Today’s history note: In 1914, Archduke Franz Ferdinand, heir to the
throne of the Austro-Hungarian Empire, was assassinated by Serbian
terrorists in Bosnia. So Germany invaded France.
World War I: Because Wars Don’t Have To Make Sense.

At 03:15 PM 8/27/98 +1000, you wrote:

The original OEM tyres were originally Dunlop and then they went to
Pirelli P600 ('81MY ? where’s Greg ?), the P4000 is the Pirelli
replacement for the 600, hence Jag owners look in their owners manual
and see the spec for what was originally on the car, ring up and ask for
it, and get told to get set of 4000’s. Nb Certain Beemers and Benzes
also used this size.

My car (86 S3) currently has these Pirelli’s on it. They’re OK. They make
noise long before the limit of adhesion, but they turn in fairly crisply
andI guess I’m really just asking too much from a nearly 2-ton vehicle.
I’m sure that for normal XJ driving,t hey are perfectly adequate.

Any good quality 70 section tyre will do just fine provided it has the
right speed and load rating. The P4000 is quieter and cheaper than the
600 but doesn’t grip as well (IMHO), the Yokohama AVS someone mentioned
earlier got very good ratings in a number of a car mag tests.

I have driven the AVS Intermedites at Mid-Ohio Raceway, they are excellent
tires on the track, and are excellent tires on the street. With the
exception of the Bridgestone Potenza S02’s, there probably is not a better
all season tire.

I was planning on putting them on the XJ6 but they weren’t in stock so I went
to the Toyo’s (not the praxes though - I forget which) I was VERY
disappointed with them, one blew last week so I replaced both Toyos with
225/60 Bridgestone G Grids, which have proven themselves on the XJ12 as
excellent in the wet and quite grippy in the dry (and damn cheap) thanks
to Jan for the recommendation.

Yeah, I run the Proxes RA-1’s on my RX-7. I have no experience with their
normal street tires. I doubt that the RA-1’s are available with a 70 profile.

Which brings me to my final point (aren’t you glad?). Although wider
wheels

and tires will give your cat a meaner look, any drastic deviation from Jag
engineered specs will place greater strain on the steering, suspension,
transmission, brakes as well as destroy the cloud like ride that the car is
famous for.

I’m sorry but I have to disagree with that as a generalisation, the 60
series on the S2 and S3 have not in way ruined the ride, and the stiffer
sidewalls dramatically improve the cornering capability.

Generally, tire flex is not an important part of a smooth ride. Relatively
soft springing, and slow damping and rebound rates on the shocks or struts
goes a lot further. Personally, I find the ride in my XJ6 to be
excessively floaty. The car dives and leans entirely too much when
cornering and braking. Doesn’t have much of a problem with squat under
acceleration in comparison. The steering rate isn’t as fast as I would
like either. Dialing in quick transitions requires large and vigorous
steering wheel movements.

Not to mention the tendency for wider tires to hydroplane on
those rainy days or nites.

Not if you buy good ones…I guess if you went 255 on the front you
might have a problem but you aren’t going to fit those in the wheel
wells anyway.

At the weight of the jag, wider tires are very unlikely to introduce that
problem unless they are vastly wider, and there is no way you would ever
put tires like that on an XJ. A 225 would probably be an excellent step up,
but faster struts/shocks and stiffer sway bars would probably give you more
bang for the buck. The Jag is definitely not using all the tire it has
because its suspension falls short, better to get the most out of exiting
tires by upgrading the suspension.

Justin G. Cordesman
Lux in tenebris lucet et tenebrae eam non comprehenderunt.