Quote:
Originally Posted by day2104
No offense taken, just make sure you consult with BMW and talk to them about your concerns. The OEM wheels when you buy are; front: 275/40 R22 and back: 315/35 R22. All I did was condense the width because of all-season tire reasons.
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Most people don't understand the way tires are dimensioned (forgive me if you do and have already done the calculations). (BTW, the dimension spec must have been done by an international standards committee who decided in fairness, a tire specification had to be partially metric, partially imperial, and to be impartial, the third dimension had to be in percent.)
What is special about the OE configuration -- 275/40 and 315/35 -- is that both tires have exactly the same circumference, and therefore have the same number of revolutions per mile. Deviating to 295/35 takes away 20mm of width (3/4"), but because of the screwy dimension standard, it also reduces the diameter by 14mm (~1/2"), reduces the circumference by 44mm (1.7"), and increases the revolutions/mile by 12 (almost 2%).
Check out the tire calculator at
www.wheel-size.com/calc/ for a visual side-by-side comparison of any two wheel/tire combinations.