tire size/ milage question?
You are absolutely correct. According to my calculations, your OEM tires are 22.65" in diameter and have a circumference of 71.16", so for every mile, each one turns 890.4 revolutions. With the larger tires and wheels, that many revolutions will get you 1.025 miles instead of 1 mile. Multiply that by the number of miles you've driven and then divide the answer by the number of gallons of gas you've used and the answer will be your gas mileage.
^ is it possible if you can help me with finding the number to multiply with my number of miles. my cars stock size is 185 65 14 and i am currently running 195 60 14. its not a big difference but i just want to get a more accurate MPG
you are actually only traveling 98.9% of what your trip count says
This is correct. I will type in the calculations a bit later.
First, calculate tire diameter:
185 x .65 x 2 x (14 x 25.4) = 596.1 millimeters, so 596.1/25.4 = 23.47 inches diameter
195 x .60 x 2 x (14 x 25.4) = 589.6 millimeters, so 589.6/25.4 = 23.21 inches diameter
The first tire will travel 73.73 inches (23.47 x pi) for every revolution, whereas the second tire will travel 72.92 inches.
If your car calculates distance based upon the OEM (first) tires' revolutions, the second tire's distance will be 23.21/23.47 of the actual distance, or .989 x the actual distance in miles.
If you had larger tires than OEM, then your multiplier would be greater than 1, as is the case with the original poster.
185 x .65 x 2 x (14 x 25.4) = 596.1 millimeters, so 596.1/25.4 = 23.47 inches diameter
195 x .60 x 2 x (14 x 25.4) = 589.6 millimeters, so 589.6/25.4 = 23.21 inches diameter
The first tire will travel 73.73 inches (23.47 x pi) for every revolution, whereas the second tire will travel 72.92 inches.
If your car calculates distance based upon the OEM (first) tires' revolutions, the second tire's distance will be 23.21/23.47 of the actual distance, or .989 x the actual distance in miles.
If you had larger tires than OEM, then your multiplier would be greater than 1, as is the case with the original poster.
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addiction2bass
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Aug 22, 2008 06:42 PM




