Tires oversize, too many changes in MPG and speedmeter?

[jmvb]

My XLT actually have 235/75/R15 - A/T tires..

I perform a TT and warrior shackles 2" lift.

I'm thinking in an 31x10.50 tires, A/T or M/T ones, with the stock rims

How many will decrease the MPG and how many will decrease the speedmeter accuracy?

Experiences?

 

[Turdle]

With 31" tires I am still dead on at 40 MPH according to photo radar, and only about 2 mph off at 65 mph. (indicated 65 MPH=67 actual MPH according to GPS)

31" tires are within acceptable limits IMO

 

[beach]

I've got 31's on warrior shackles and monroe coil overs, and TT in the front with extended Ranchos, more than 2", think I was around 3.5-4" of lift as the coilovers added more than normal shocks and 2wd so I could crank the TT higher with 100mm bolts. Don't really see any difference in speedo or mpg city or highway, maybe just slightly less in city driving. No loss in power either but I'm 2wd and 3.73 gears with the V8. But I have procomp alloys which are light weight at 15lbs or so. Nankang FT7 A/T which are pretty light for A/T as well.

 

[jmvb]

Thanks!!

 

[jmvb]

Got this ones!

Pro Comp Xtreme A/T 31x10.50R15

The speedometer say 90KM/H, actual 100KM/H

To be continued...

 

[1996BLKBauer]

When I swapped to 31's with a torsion twist, and shackles, I got slightly less MPG's maybe .5-1mpg difference per gallon, I also added a lot weight with the wheels and tires, it does coast nice now though. speed according to the math is roughtly 3.5-4 mph faster at 45mph, but I have NEVER been pulled over for going over the speed limit on my speedo. I have however been pulled over for my lights being to bright though, lol.

 

[1998Exp]

Theoretically, the 31" tires are 2.1" larger than your stock, which translates to 7.3%, so that will be the nominal speedo error. Most speedos appear to be calibrated to read 3-4% high (to be on the 'safe side of the law', especially when tires wear down), so yours will probably end up reading 3-4% low. No idea about MPG.

My XLT actually have 235/75/R15 - A/T tires..
I'm thinking in an 31x10.50 tires, A/T or M/T ones, with the stock rims.
How many will decrease the MPG and how many will decrease the speedmeter accuracy?