Right, got to be diligent when driving nice cars but for the most part, it's very safe in this part of the world now.
I'm using 18" on the Z4 in the standard 225/40R18 - 255/35R18. The 2.6/2.9 bar is 38/42 psi and is on the high side so am wondering if higher pressure can improve traction?
I do have the PSS 19" on another car but it has adaptive magnetic shocks and awd so I don't loose traction on them. Maybe it's the 18" size or the Cobb tune giving too much torque?
