How much is my odometer off w/ 31x10.50's?

[paxj92]

I have an 91 xj w/31x10.50's. I am trying to figure out what kind of gas milage am getting. How much do the tires throw off my odometer?

 

[Slo-Sho]

Well every rig is different as well as overall tire sizes. The easiest way is to get on the highway and compare your trip odometer to the points between two mile markers. This way you'll have an idea right down to the tenth.

 

[paxj92]

Thanks.....to the highway I go

 

[89xj]

I have an 91 xj w/31x10.50's. I am trying to figure out what kind of gas milage am getting. How much do the tires throw off my odometer?

roughly 10%-12% depending on actual tire diameter

 

[igotanxj]

you can look up the revolutions per mile of your tires on tirerack, then do some simple division to find out the difference in percentage.

My tires have 11% more revolutions per mile, therefore i multiply my mileage by 1.11 to get the real mileage.

 

[89xj]

you can look up the revolutions per mile of your tires on tirerack, then do some simple division to find out the difference in percentage.

My tires have 11% more revolutions per mile, therefore i multiply my mileage by 1.11 to get the real mileage.

or to get a rough estimate using your head, going from a 28" tire to a 31" tire is a difference of 3" which is roughy a 10% inrease in size

 

[MrShaft696]

faster you go worse it gets, going like 80 was like 67 or so when i went I first went to 31's on 3.07s now on 3.55s its back to stock.

 

[Yucca-Man]

or to get a rough estimate using your head, going from a 28" tire to a 31" tire is a difference of 3" which is roughy a 10% inrease in size

All y'all who say the adjustment from stock to 31 is the ratio he will be pff are wrong. The stock tires are almost always under actual mileage/speed. Somewhere around a 29 or 30 (it varies, including variance in actual tire diameter) is where you'll find the odometer is actually correct.

Jim www.yuccaman.com

 

[igotanxj]

or to get a rough estimate using your head, going from a 28" tire to a 31" tire is a difference of 3" which is roughy a 10% inrease in size

The problem is, tires arent always the size they say they are. A 31 can be 30 or 32 inches, a 28 can be 27 or 29 inches. Plus, you can't do it that way with metric sizing. This way its more accurate, and could be the difference between your odo telling you 15mpg instead of 13 mpg.

 

[BigRed86]

I have 31 BFG A/T and for a 25 mile trip my odometer tells me its only 23.5 or 23.7 can't remember the decmial. and for speed with 3.55 gears when i get up to 65MPH I am actualy going 70 MPH (thats what my GPS tell me though). just my $.02

 

[89xj]

The problem is, tires arent always the size they say they are. A 31 can be 30 or 32 inches, a 28 can be 27 or 29 inches. Plus, you can't do it that way with metric sizing. This way its more accurate, and could be the difference between your odo telling you 15mpg instead of 13 mpg.

yes i know, i said that in the post i made before that, just not in the post you quoted.

 

[smcdonaldaz]

All y'all who say the adjustment from stock to 31 is the ratio he will be pff are wrong. The stock tires are almost always under actual mileage/speed. Somewhere around a 29 or 30 (it varies, including variance in actual tire diameter) is where you'll find the odometer is actually correct.

Jim www.yuccaman.com

I agree with Jim. I used my GPS after going from 215s to 235s and with the 235s my speedo was right on.

 

[300$XJ]

http://www.miata.net/garage/tirecalc.html this is what I use its pretty close, put in your factory size and your new size and it should be good, it will tell you the % you are off, for me it's like 10% going 9.6% to be exact but 10% is an easier number to figure. It's not exact but it's close!

 

[NW-ZJ-SCOTT]

i have 31 10.50s aswell, and at 55mph im doing 62mph at 70mph im doin 81mph.