Quote:
Originally Posted by pylon
On your sidewall (the side of the tire), there will be a series of numbers and letters (digits and symbols used for communication in various languages).
eg: 235/45R/18 or something similar.
I need that.
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The 18 is the really important part if you
aren't swapping to larger diameter rims. So long as you know how to keep the sidewall ratio close, you can play with the first two.
I use the Tire Rack calculator on E90Post:
http://www.e90post.com/forums/forumdisplay.php?f=12
EG: Stock tires on a 335i are 225/45/17. I moved up to new 19" wheels and put 275/35/19 on the rear. Difference in diameter is -0.165" or -.622%, which means my speedometer will read the same at 60 MPH. Of course, as speed increases, this will ultimately cause my speedometer to read
lower than it should, but the difference will occur at speeds that I'm already breaking the law anyway.
