Tire brand/type is almost certainly a factor. I've still got some four-year old BFG R1's and get my best times (on asphalt) with 31F/24R. The sidewalls on the R1's are about the stiffest ever made, so you don't need lots of pressure to stiffen them up to prevent rollover. I'm just trying to finish off the year with them, then I'll have to get some other tires. Any good suggestions/commentary between the Yokos, Hoosiers, and Kumhos anyone? BTW, I do have some spare Hoosier 205/40-16s with eight autocrosses on them. Anyone interested ($150 + shipping for all four)?
