Formula Needed
#1
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Formula Needed
Can someone point me to a formula for calculating the gas mileage with my new tires. I went from the stock 265/70/16's(31")to some 265/75/16's (32"). I know that I travel a bit farther than the odometer says because of the increased size, but I don't know how much. This throws off my gas mileage calculation some because I'm not dividing into the right number. Does anyone know of a formula to correctly calculate the true mileage gone with the bigger 32's so that when I divide by the gallons used it will be more accurate?
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Originally Posted by 03TRDBlack
Can someone point me to a formula for calculating the gas mileage with my new tires. I went from the stock 265/70/16's(31")to some 265/75/16's (32"). I know that I travel a bit farther than the odometer says because of the increased size, but I don't know how much. This throws off my gas mileage calculation some because I'm not dividing into the right number. Does anyone know of a formula to correctly calculate the true mileage gone with the bigger 32's so that when I divide by the gallons used it will be more accurate?
old tires = (265/25.4*.70*2)+16 = 30.61"
new tires = (265/25.4*.75*2)+16 = 31.65"
(real miles) = (odometer miles) * 31.65/30.61
or
(real miles) = (odometer miles) * 1.034
that is you're going about 3.4% farther than your odometer reports, and that means you're getting 3.4% better gas milage than you're currently calculating.
edit: that also means you're going about 3.4% faster than your speedometer reports. but since speedometers usually underreport the speed, you're probably right on. i usually double check mine with those radar speed limit signs that have been going up everywhere.
Last edited by mike_d; 09-28-2004 at 02:14 PM.
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Originally Posted by 4RUNR
I'm having real doubts about our educational system, judging by how many times this sort of question was asked
#6
Originally Posted by mike_d
yeah, i've posted that formula about 3 or 4 times myself. maybe someone should search the posts and just count how many times that's been posted. i'm too lazy to do it myself
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Circumference is diameter * 3.14
If you're talking about tires, it's more accurate to use (static loaded radius*2) *3.14.
Not particularly useful to figure gearing/tire changes or fuel mileage tho.
If you're talking about tires, it's more accurate to use (static loaded radius*2) *3.14.
Not particularly useful to figure gearing/tire changes or fuel mileage tho.
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#8
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Originally Posted by Flamedx4
Circumference is diameter * 3.14
If you're talking about tires, it's more accurate to use (static loaded radius*2) *3.14.
Not particularly useful to figure gearing/tire changes or fuel mileage tho.
If you're talking about tires, it's more accurate to use (static loaded radius*2) *3.14.
Not particularly useful to figure gearing/tire changes or fuel mileage tho.
I have a gear/tire size/speedo calculator page on-line here...
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