[fam]

Stock size is 185/55R15

I Have to use a 15" wheel to stay in HS class of autocross\solo but they dont make performance tires that size so basically im wondering how wide and how tall of tires have been put on stock rim and work fine if anyone knows?

Basically my options are

195/50R15 82V $102.00 (ea.)
195/55R15 84V $99.00 (ea.)
205/50R15 86V $112.00 (ea.)
for the Direzza Sport Z1 Star Spec

or if I go R compound

hoosier a6
205/50ZR15 $221.00 (ea.)
225/45ZR15 $228.00 (ea.)
275/35ZR15 $266.00 (ea.)

 

[DrWebster]

Well, the 195/50-15's are going to be the closest match to stock if you're concerned about both fitting the wheel and maintaining about the same overall diameter. I don't know what the absolute maximum you could put on would be, but I wouldn't try to go any wider than 205's unless you plan to buy wider wheels to match.

 

[fam]

Id be buying a used set of miata or mini cooper wheels since theyre 4x100. Not so much worried about the wheel size as I am the internals of the wheel well (dont want to risk any rubbing on a new car)

 

[Traum]

If you are going with the Star Specs, the choice will be between 195/50R15 and 205/50R15 86V. The 195 will give you a slightly better gearing, which translates into better straight line acceleration. The 205 will give you better lateral grip, but at the expense of sloppier turn in and steering feel because your stock wheel (15x6?) would not be able to provide the best sidewall support for the tire.

If you are going R-comps, I'd consider using 225/45/15 up front, and 205/50/15 in the back for a reverse stagger setup. That should help the car rotate better at the autox, and that is precisely what you want the car to do.