this question is sorta like beating a dead horse but im curious..
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Professional
Joined: Apr 2009
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From: Moscow,Ohio
this question is sorta like beating a dead horse but im curious..
if the sticker on door of my 03 4.7 dak shows tire size of 245-70-16s... but i bought the truck new ( 2 miles on odometer) with tires that are 255-65-16's i got better gas mileage out of the wider tires.. wouldnt the oem taller skinnier tires give me better.. or would the computer recompensated for the tires or would i had to have done something to the computer to recalibrate it for the tires.. so in essence should i go back to original tire size that i bought truck with ?
Curiousity @ 330am..
Schuey
Curiousity @ 330am..
Schuey
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Joined: Jan 2007
Posts: 2,007
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From: Willow Street, PA
the larger tires probably change your mileage and speedometer readings but I am not sure which direction it would take it...with my superchips i have 31's but for the speedo to be on right i need to set it to 29.75 if i were to change that it would also give me false mileage readings if you get what i'm trying to say haha
Professional
Joined: Mar 2010
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From: Okemos, MI
Well, if my understanding about how the tire size numbers work, and if the two different tires are consistent with one another (that is, there are no differences attributable to the manufacturer), then the 245 / 70 tires have a sidewall only 6.5 millimeters taller than than the 255 / 65 tires. Personally, I doubt that difference is enough to notice by itself.
Consider - your 16 inch rim is 406.4 mm.
Add the 245 / 70 tires and your height is 749.4 mm.
Using the 255 / 65 tires, your height is 737.9 mm
12 mm difference in overall height of the tires and wheels. That is less than 1/2 inch. Like 1.5% difference.
Any calculation based upon your odometer with the smaller tires would be off, as the odometer is now incorrect.
The taller tires should get you better mileage on the freeway, but they are more difficult for the truck to get turning, so you lose some in-town mileage.
IMHO, the effects of tires themselves on gas mileage are essentially meaningless. Unless, of course, you go from like a 14 inch 195 / 75 to like a 33". Obviously, there is a major difference there. But, your tires are, for practical purposes, the same height.
Furthermore, I think that increasing air pressure to squeeze out mileage is a myth as well. What does over-inflation cost in terms of additional tire wear? Is that cost worth the benefit in mileage? Who knows.
I guess I am saying that the difference would be meaningless in my perspective. Just buy a good set, rotate them, keep them at the proper air pressure, and be happy. If you want an increase in gas mileage, there are better ways to get it, IMHO.
Consider - your 16 inch rim is 406.4 mm.
Add the 245 / 70 tires and your height is 749.4 mm.
Using the 255 / 65 tires, your height is 737.9 mm
12 mm difference in overall height of the tires and wheels. That is less than 1/2 inch. Like 1.5% difference.
Any calculation based upon your odometer with the smaller tires would be off, as the odometer is now incorrect.
The taller tires should get you better mileage on the freeway, but they are more difficult for the truck to get turning, so you lose some in-town mileage.
IMHO, the effects of tires themselves on gas mileage are essentially meaningless. Unless, of course, you go from like a 14 inch 195 / 75 to like a 33". Obviously, there is a major difference there. But, your tires are, for practical purposes, the same height.
Furthermore, I think that increasing air pressure to squeeze out mileage is a myth as well. What does over-inflation cost in terms of additional tire wear? Is that cost worth the benefit in mileage? Who knows.
I guess I am saying that the difference would be meaningless in my perspective. Just buy a good set, rotate them, keep them at the proper air pressure, and be happy. If you want an increase in gas mileage, there are better ways to get it, IMHO.