Originally Posted by MAR
Anone know why BMW puts 215/40/18 front and 245/35/18 rear on the 135 when everyone seems to think 225/255 is better? There must be a reason BMW uses that as the OEM setup.
BMW doesn't size wheels for the enthusiast, but follows the laws of averages. Some have upsized wheels with some regret, and others love them.
It is purely a personal preference and the compromises you are will to live with.
For my, traction and ride quality was an issue with runflats OEM wheel sizes.
I replaced my wheels with lighter and wider wheels. After 4000 miles, I am a bit mixed. Traction is other worldly, but straighline tracking is a bit iffy and while the ride quality softer it isn't necessarily better without replacing the front suspension with M bits.
I will go back to OEM runflats and OEM wheels after I have blown through this rather expensive experiment in wider and lighter tires.