Martin S.

You have one laying around? I am interested if it is true and straight, cosmetics no big deal, going to be a track wheel. FOUND ONE!

Matt Lane

Just wondering, what track tires (and sizes) are commonly used for these 7 and 9 inch wheels these days?

Best,

Matt

Martin S.

235/45/17 front and 275/40/17 rear...this combo keeps the front to rear rolling radius delta to approximately 1.3%....a key parameter if you want your ABS to work. On the 993 the front to rear rolling radius delta cannot exceed 3%....

If you go to 18", (8" front 10" rear) you can increase the front width to 245 and the rear to 285, however the tires are heavier and cost more. You can also lower the aspect ratio a wee bit...lower profile tires.

Now let's have somebody step up and by my wheels!

mongrelcat

Interesting, I had no idea you could use such a wide tire on the Cup-II's. Thanks, and good luck on your hunt.

Matt Lane

Hi Martin - yeah, I was surprised as well as to how wide you can properly mount on 7's and 9's.

Consider it a free bump!

Matt

Martin S.

Actualiy, a 235 tire should have an 8" wheel...have you priced out a 17" X 8" wheel? Pricy! So much so for me that I mounted up the 235 (RA-1) on a 7" wheel(s).

Also, the wider front tires help dial out understeer, or so I have been told.

mongrelcat

So what do you recommend for street usage with an occasional track day? 225/45 (F) / 275/40 (R) ?? I'm looking at set of Sumi HTRZ-III's which seem to come in a large variety of sizes, but no 265.

I've found a 40lb bag of kitty litter in the trunk has the same effect (fits perfectly too.)

Sent you a PM regarding a lead on the wheel you need.

Martin S.

I am just a hack so I dont recommend...

Actually (Well OK, here is a mini-recommendation), the 205/255 stock sizes work great, the higher the aspect ratio, the better the ride. If you rip around corners and all that speedy stuff, then plus up to the 225/275 should be fine.