[rdane]

Thanks for the additional info guys.

One of the local hot shoes runs 8x15s Fuchs all around and R rubber on his light weight 3.6 and does very well on the track against much "better" cars on a regualr basis.

I had thought about 7 and 8 x 15" Fuchs and adding longer studs but was worried about loss of tire contact patch, braking, traction ect. with the smaller tires available.

I can legally run anything in class (wheel and dot tire) that will fit under the car.

The hill climbs/time trail is always on cold tires and under 3 miles long.

Top speed on the straights is under 90mph. So it is all 2nd and 3rd gear. But it is a exercise in "squirt" technology and torque if you can stay glued to the road. The R rubber should give me a bit more speed to carry through on to the straights. The highest top speed in the trap wasn't the fast run on the hill which surprised me. So cornering and top speed have to balance each other out to have a good run time.

Most of the gearing is already there in a purpose built short gear box. I just don't want to give up any of 2nd or 3rd gear to a larger tire dia.

Stick to the A3SO5 on the 16" wheels? Or build a 15" wheel set with the same tire?

I appreciate the help, thanks.