Apologies for going off topic. In my experience I've found that Caltracs will need more pressure in the tyre by design. A lot of the faster guys use a radial or a stiff sidewall, especially in a heavier car. Our Challenger would kill the sidewalls in a bias ply way before the "tread" was gone. A buddy tried some of our old slicks in his 10 second '55 Chevy, I did warn him, he made 2 passes and parked the car