I just purchased a new set of 4 Pirelli P Zero tires for my 00 XK8. The original sizes on the car were 245/45 ZR 18 96Y on the front, and 255/45 ZR 18 99Y on the back. After buying the new set and having them mounted I discovered when I got home that while the rear are exact replacements, the front ones are the same except for being 99Y rated instead of 96Y. I know that the numbers 96 and 99 refer to the weight capacity of the tire, while the Y refers to the speed rating of the tire. I called the shop where I purchased the set and they said it really doesn't matter, there will be no difference in performance.

So I'm wondering if anyone here can comment on this. I would imagine the only possible problem with the different rating would be that the 99Y tire would be a bit heftier and perhaps cause front end issues?

Thanks for reading.

Manco

 

Will not make any difference at all, if it was going the opposite way and was lower it could possible cause some issues.

I would not worry about it

 

Since the sizes are the same as my 2001 XK8 and your fronts can carry more weight, there should not be any problem due to the increased capacity.

Maybe someone knows if there is really any structural difference in the tire or if it just passed the test at a higher level, so they put the higher rating on the tire.

What tire pressures are you keeping?

Could you keep up updated on the wet/dry/comfort/treadwear/tramline performance?

 

If anything it should be better as the 99Y refers to load rating / speed rating I believe.

This is something to watch out for in future.

99Y is probably along the lines of ( 99 = 1709lbs load rating ) and I'd say the Y would speed rate it at 186mph so you should in actual fact be better off as the 96 would be rated at around 1565lbs

All good!!

Please feel free to check out any tyre website for your own pace of mind

 

Thanks for the helpful reply. I've got the fronts at 32 psi and the rear at 34 psi, as indicated in the vehicle care manual. So far they feel great. I'll keep you posted if there as to any noticeable positive or negative results.

Thanks again.

Manco

 

Thanks. I'm thinking along the same lines as well. The higher load rating should be a plus, not a negative. Still, I'm curious as to why Jaguar would specify 96Y in the front and not 99Y if not for some specific design reason. Oh well, so far I'm enjoying the ride with these new Pirellis and there doesn't seem to be any downside......yet!

Manco