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Tire Circumference
I've been curious for a while about the circumference of tires. I have particularly been wondering how close calculations are to the tire curcumference. These have an effect on acceleration times due both to moment arm length and actual speeds. Tire pressure would matter somewhat as well.
I mounted two different tires, put chalk marks on the tire and ground and pushed the car forward. Distances were measured. Here are results:
Tire Size Measured Computed
225/60 - 16 80 inches 83.7
245/45 - 16 74.5 inches 77.5
225/50 - 16 ??????? 78.1
Thus if the 225/60 -16 tires gives the true speed of 100 mph, the 245/45 - 16 tire only is going 93.125 mph. Big difference. The computed column was done by the data in the tire designation.
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