What wil 37" tires do to my gas mileage

[DrScoles]

I'm on my third H2, finally gonna get aftermarket rims and tires for it. The person who has been helping me, said that 37" fit fine. My big concern is what will this do to the already dismal 11mpg???

Thanks, Mike

[GLBLWARMR]

Putting larger tires on the truck will definatley improve the gas mileage by like 15-20 mpg.

[DRTYFN]

Depending on how aggressive the tread is, you'll lose about 1-1.5 mpg. Also remember that a larger tire will result in a reduction in actual milage shown on the odometer.

[The Green Lantern]

Originally Posted by DRTYFN

Also remember that a larger tire will result in a reduction in actual milage shown on the odometer.

If your tires are not calibrated. Larger tires are making less revolutions per mile which means you're going a bit farther than a mile when your odometer shows you went a mile.

[GLBLWARMR]

Originally Posted by The Green Lantern

If your tires are not calibrated. Larger tires are making less revolutions per mile which means you're going a bit farther than a mile when your odometer shows you went a mile.

As long as the highway distance markers are set correctly, then when I went a mile my odometer showed .9. So there is about 1/10th of a mile difference per mile.

[PARAGON]

Originally Posted by The Green Lantern

If your tires are not calibrated. Larger tires are making less revolutions per mile which means you're going a bit farther than a mile when your odometer shows you went a mile.

a larger tire will result in a reduction in actual milage shown on the odometer

[PARAGON]

Originally Posted by The Green Lantern

If your tires are not calibrated.

could you explain this process of "calibrating tires"? thanks in advance

[PARAGON]

Originally Posted by GLBLWARMR

As long as the highway distance markers are set correctly, then when I went a mile my odometer showed .9. So there is about 1/10th of a mile difference per mile.

I think it's actualy 7/100ths difference. Of course, that's just from memory.

[Captain of the Titanic]

Speedo/Odometer change is simple (and I'll include gear changes):

Old Tire Diameter: OTD
New Tire Diameter: NTD
Old Gear Ratio: OGR
New Gear Ratio: NGR

NTD/OTD * OGR/NGR = percentage difference from stock speedo/odo.

In the case of my previous vehicle, a Tahoe, I went from 31" tires to 35" and changed the gears from 3.73 to 4.11.

This yielded 35/31 * 3.73/4.11 = 1.0246 or a 2.46% change in speedo/odo.

More importantly, the gear change brought the highway traveling speed back into the "sweet spot" of around 2100 rpms and put my MPG back where it was (close anyway) to pre-tire change.

In your case 37/35 is simply a change of 5.7% This is not, in my opinion enough to justify a gear change. I would look into headers and dual exhaust to recoup that small loss of MPG.

Personnally I think I will stick with the 35s on my H2. I do a lot of driving offroad, but not anything that 37s would make a difference in.

Now a set of 40s and a 6 inch lift...hmmm....

[DRTYFN]

Originally Posted by The Green Lantern

If your odometer is not calibrated.

Fixed.

[Agriv8r]

Originally Posted by Hummerster

Why do you give a fawk about mileage.. you drive a Gas Guzzling POS Hummer. You really shoudl /self now!

saw a jeep with 37" tires, they were strapped to the roof and being delivered to a HUMMER dealer, best a jeep has ever looked (covered up by tires)

[ROX]

Originally Posted by PhilD

Simple, you measure the distance between the closest points of the tire edges with stock tires, then measure again with the larger tires. Divide by Pi, then X2. you then need to move the rear axle back that amount

No Phil, it's divide by Pi squared, not x2. sorry to have to correct you on that.

Once the axel is moved back by that amount your mileage should double back to 11 mpg.

[ROX]

Originally Posted by Hummerster

Why do you give a fawk about mileage.. you drive a Gas Guzzling POS Hummer. You really shoudl /self now!

again

[Vettster]

Originally Posted by Agriv8r

saw a jeep with 37" tires, they were strapped to the roof and being delivered to a HUMMER dealer, best a jeep has ever looked (covered up by tires)

You forgot to mention that he had to make 4 trips.

[Agriv8r]

Originally Posted by Vettster

You forgot to mention that he had to make 4 trips.

thanx for the correction