Quote:
Originally Posted by gaijin
I very recently upgraded from factory 17's to aftermarket 18's at 8.5 widths. Went with the newest Bridgestone A/S at 245/40R18. I noted a 3 mph difference between the car and my iPhone's digital speedometer.
Additional point. I upgraded from OE 225/50R17 Conti Run-Flats. The non-R/F rides are much nicer and quieter too.
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fyi - the speed difference is mostly the way the speedometer is set from the factory. A 3 mph difference is pretty standard on all BMWs (and most German cars).