[JimD]

I used the white stuff sold at auto part stores to mark windshields with prices to mark my tires last autocross a couple weeks ago. There are little triangles to mark the edge of the tread on the upper sidewall of your tires. I put the white stuff in this area extending onto the tread and the sidewall. Then I made some practice runs and inspected. I started 4 over the door jamb which for me in my 128i convertible meant going from 32/36 to 36/40. That was plenty in the rear (white stuff still on all the sidewall and a little of the tread (but very little), but not enough in the front (rubbed off the white stuff well onto the sidewall). But my tires would not get back down to where they started between runs. So I made the fronts the same as the backs. I also had about 2psi difference between the sunny side of the car and the shaded side. So I made the front on each side back the rear on each side. When I got home and measured them cold, the fronts were about 38.5 - so not totally up to 40 psi cold. I was still on the sidewalls a little bit so I will go with 40 psi front and 38 or 40 psi rear next time.

Jim