I had the same question. Tirerack recommended using the same tire pressure as the OEM setup. However, I inflated it a little more. I am currently using 32 psi in front and 34 psi in the rear.

Eric


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'00 E430 w/ Solaris H-7's
Brabus 19'' Monoblock V, 2 piece
H&R Sport Springs

'99 SLK230 Sport