Hello,

I was wondering if anybody tried fitting a 265/40R18 tire on the 8.5" wheel that come standard on the rear of the 07 touring. According to the tire specs it needs a 9" wheel but I heard people fitting tires on wheels 0.5" narrower than required by the tire.

The follow up question would be if you happen to know the disadvantages of doing this?

I am using my car for AutoX and I don't want to change rim sizes because it would take me out of the stock class but I want to add as much rubber as possible. With the current rims I can upsize(and be within tire requirements) by 20mm on the front but only 10mm on the rear.

Thank you very much,
Cipri

 

I am always curious about upsize tire questions. Instead of a wider tire what about a better tire?

 

It's out of spec, but it's been done, and without much ill consequences. However, the end-user running a tire on an out-of-spec rim without any problems is far from any form of testing a manufacturer actually does. If you choose to do so, you may have to mess with tire pressures to get an ideal contact patch and in doing so there's no guarantee that tire pressure would/wouldn't begin to border being out of spec.

With all that being said; stock class in autocross is allowed any type of tire. That usually translates to drivers using the widest possible tire that the rim can be physically wrapped with and modifying the pressure to ensure a good contact patch. All in the name of reducing time and being competitive. On top of all that, they don't use street tires.

If your tires are for dual purpose, just get ones that fit properly. When you want to begin running competitively(in stock class), get some race rubbers and find an extra set of identical wheels in the FS forum. If you want to stay on street tires, the only street tire class for the Z (non-local) is STR, and has a 255 limit (which the Z is mostly non-competitive anyway).

 

265 is about max on an 8.5. I run a 275 rear and 265 front on 9" width wheel.

 

Thank you. I am indeed using the same tires for both street driving and AutoX. I wasn't aware of the 255mm limititation and I will have to read more about that.

Cipri

 

If by better you mean a race tire that is still not what I am considering. I run in street tire class thus researching which is the best tire is one part of the problem and beeing able to increase the contact patch is another part of it.

Thanks,
Cipri

 

9" - sigh. I need to see if I can have that but I'm not sure

Cipri

 

What class are you running in?

 

I'm running in Street tire and for index I'm C stock(XCS)

Cipri