Quote:
Originally Posted by subxero
^ seriously, why are you dividing the aspect ratio difference by 2?
|
I don't know about divide by 2, but it seems that the discussion is missing the multiply by 2 that is necessary when calculating tire height. Yes - 140/70 means that the height of the tire is 70% of 140, or 98mm. But that's on both the top and bottom of the wheel, so the overall diameter of the tire is 98mm for the top of the tire, + 17" for the wheel diameter, + 98mm for the bottom of the tire. A difference of 7 mm in the calculated tire height of the tire itself, by tire size, would be a 14mm difference in actual tire diameter on the bike, right?
All of this gets fuzzy in the real world, as the tire sizes themselves aren't exactly accurate, and differ based on manufacturer and type of tire.