Thread: Track day tires
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      06-22-2011, 06:07 PM   #30
hollysmac
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Drives: 2020 Bmw 228xi Gran Coupe
Join Date: Jan 2011
Location: Kennesaw,ga

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Quote:
Originally Posted by hwelvaar View Post
Thanks, I played around with that tire size calculator:


Tire Size Comparison
Specification Sidewall Radius Diameter Circumference Revs/km Difference
265/35-19 93mm 334mm 668mm 2099mm 476 0.0% (stock size)
265/35-18 93mm 321mm 643mm 2019mm 495 -3.8%
285/35-18 100mm 328mm 657mm 2063mm 485 -1.7%
295/35-18 103mm 332mm 664mm 2085mm 480 -0.7%
265/40-18 106mm 335mm 669mm 2102mm 476 0.2%
235/40-18 94mm 323mm 645mm 2027mm 493 -3.4%

So indeed you would need 295/35-18 or 265/40-18 to not influence speedometer.
However, the last size (235/40-18) is BMW's recommended winter tire size.
It has -3.4% size compared to stock tires, which is not that diffefent from the 265/35-18 size (-3.8%).

And by checking some online tire shops, I get the impression that 265/35-18 is a more common size than 265/40-18. For example Toyo R888 seems only available in the size 265/35-18.
Thanks! I plan to use the 18" track wheels from my e46 M3 and use the 265/35-18s as soon as I get the wheels up from my son's shop in NC.

Holly
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