true odometer reading with larger tires
09-21-2004, 01:44 PM
#1
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true odometer reading with larger tires
i've been thinking about this as of late, but i don't know what the formula would be for this. im trying to figure out how many miles on each tank im getting, and with larger tires on, i know the odometer isn't reading correctly. anyone know how to calculate true miles as to the odometer reading? my original tire size on the truck were 28's i believe, and now im running 33's.
09-21-2004, 02:15 PM
#5
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http://www.miata.net/garage/tirecalc.html
Just increase your mileage by the difference in percentage. For example, my tires are 7.3% larger than stock - 214.3 miles + (214.3 x 7.3%)=229.94 actual miles.
Just increase your mileage by the difference in percentage. For example, my tires are 7.3% larger than stock - 214.3 miles + (214.3 x 7.3%)=229.94 actual miles.
09-21-2004, 02:19 PM
#6
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this was posted by 00Runner on a different thread.
so, im actually getting about 20.5 mpg if thats right.
I'm not sure if the gears change anything since I'm not sure where the odometer gets it's reading from. Assuming that it's at the wheel, then you could correct your mileage be figuring the difference in the circumference of the tires. For example, if your truck came stock with 31" tires that gives a circumference of 97.34" (Pi x diameter). A 33" tire has a circumference of 103.62". Divide 103.62 by 97.34 and you get 1.06. This is your correction value. If you multiply your odometer reading by 1.06 you will get closer to your actual mileage. So if your odometer reads 250 miles on a tank, you really went closer to 265 miles (250 x 1.06 = 265).
09-21-2004, 02:36 PM
#7
Registered User
I just use the highway mileage markers. My odometer shows exactly 9/10ths of a mile for every milepost so I'm off 10%. When my speedo shows 50 mph, I'm actually doing 55, and when it shows 30 I'm really doing 33, etc. When my odemeter shows 100 miles, I've actually gone 110.
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