This is the size that I use on my M Roadster. We both use 5mm spacers (well, he says 1/4", which is a bit more) up front to prevent rubbing. The 275's fit fine in back.

Both of us use stock wheels.

This is for autocrossing only. My attitude now is that I'll run cheap stuff on the street, where it doesn't matter.

From what I read awhile back, I believe Mark Sipes uses 245/40/17 in the front.

Some have experienced wheel rub with the stock spring/shocks.

I'm hoping that the stiff coilover set up in front will counter this.

Have to wait and see.