How do I figure out what is the correct size slick for my car?

I'm currently running Hoosier R6's...275/35/18 up front on 9" rims...and 295/30/18 in the back on 11" rims.

I've got a 968 which weighs about 2,650 lbs.

It's set up with Motons, and has about 3 degrees negative camber up front, and about 2 degrees negative camber in the back.

I'd like to try running slicks, but I don't know the correct compound...or the right size!

Sheesh!

This seems like such a newbee question...But, I don't know how to figure it out!!

 

Jason,
Check out Bob Woodman tires. Pirelli race slicks come pretty close a 265/645/18 would work well in the fronts and 295/680/18 in back. Woodman has a size chart.
FWIW, you will not get the performance out of the tires without a spring rate change and Pirelli slicks are expensive! Good luck but don't expect them to be a magic pill for 3 seconds a lap, it won't happen.

I ran slicks for two weekends and went back to Hoosiers. They didn't give me the wear I thought I'd get.

 

That's exactly the right fit for my rears! I just tried a Hoosier.

The fronts are probably going to be 250/650/18.

Thanks!