View Single Post
      01-26-2013, 08:05 AM   #20
Just one more taste...

Drives: 2010 135i
Join Date: Aug 2012
Location: Shirley, MA

Posts: 1,419
iTrader: (14)

Originally Posted by ///Chase
Originally Posted by b1aze View Post
Isnt 225/40/19 a really tall tire? Stock size is 215/40/18. Thats a 5% difference in rolling diameter.
nah mate thats the width, the 40 is the sidewall height.
Sidewall height is a ratio. A % of the width. A 245/40/19 has a sidewall height of 40% of 245mm, which is 98mm ( or 3.82") over the wheel diameter (19"). 2x sidewall height + wheel diameter gives you rolling diameter.

Google "tire diameter calculator" for further confirmation.