As long as the replacement tires have the same overall diameter as the P-Zeros ( 28.7" ) the speed/odometer should not change. Check out this thread
http://www.camaro5.com/forums/showthread.php?t=106945 Also the first time it snows you might want to very gently drive to a wide open parking lot and practice starting stoping and turning in the snow. I live in Indy and the first snow every year is a zoo.