Karl in Cup(as in PCA) you can run wheels up to 8's and 9's as a Cup car at 2600Lbs. As a Spec car at 2530 you must run by Spec rules which means only the 225/50-15 Spec tire and wheels.

Bill

Nope, tire size is specified in the rules. The tires seem to wear well as is. I squeezed 225/50/15 RA-1 on the 15x6" rims on my old 924S (before it was a race car) - that looked goofy, but didn't work too badly. I'm sure 15x8's would improve things a bit, but are pricey and rare, hence not in the Spec rules.

Karl @ ART wrote:

QUOTE:
Has anyone run a 205/50 R15 RA1?

205/25.4 = 8.07"
225/25.4 = 8.86"

Rims are 7" wide. I've yet to put a track mile on the 944 so I really don't know, but the math says the tire is too big for the rim.

The Hoosier is cantilevered. The Toyo is not.

We went from 15 x 6 rims to 15 x 7s in the early days of SM while still maintaining the 205s. The tires wore better and the laptimes dropped.

Going to a 205 instend of 225 will not have the same impact as going from 6" wheel to a 7" wheel with a 205. Using a 8" wheel does not fit in goals of 944 spec.

We use 15x7's in 944 spec since they were the most common stock wheel use on these cars. 75% of donor cars a came with 15x7 wheels (either phone dials or cookie cutters). The 924S came with 6" wheels, but can run 7's. There were some optional 8" wheel used on these cars, but they are rare and only in one offset. As such 7's are the only way to make sure everyone is on the same size wheels.

As for the 225 fitting on the wheel it does fit properly is in the recommeded size range for the Toyo 225/50 tire.