I have a stock 1992 BMW 525i with the 15" bottlecaps. My current tires are, I believe, 205/65 15". A friend of mine has 205/60 15" Michelin Energy MXV4 Plus's that he's giving me a great deal on. Is the 5mm less sidewall going to chance my speedometer reading at all? If so, how much? Would you recommend against it? I'd be getting these tires with 95 percent tread for 30 percent of the original cost.

TIA!

aspect ratio is not sidewall size. It's a ratio. You're going from a 25.5" diameter tire to a 24.8" diameter. Stock size yields 824 revs/mile and your "new" tire is 837. Your speedo will read roughly 2% higher than actual speed.

aspect ratio is not sidewall size. It's a ratio. You're going from a 25.5" diameter tire to a 24.8" diameter. Stock size yields 824 revs/mile and your "new" tire is 837. Your speedo will read roughly 2% higher than actual speed.

Woah. Thanks a million!