How have the 255/35/20 DWS06+ tires worked for you? I have a M3P with the 20" Uberturbine wheels and stretched 235/34/20 tires. I don't like the stretched tires. I have been thinking of getting 18" wheels and 245/45/18 DWS06+ tires but It would be cheaper to get the tires you have. Do you have any problem with clearance? With the 255/35/20s do you have a speedo calibration problem?