H2 needs new shoes, I have 35" right now, thinking of going to 37". Guy at discount tire said it would HALVE my mileage.... I think he's crazy. I know it will screw up the speedo, not a big deal, but what will it do to my mileage?

Thanks, Mike

 

Latest issue of Car and Driver has an interesting article on this where they take a VW and test performance and fuel economy differences of 15", 16", 17", 18" and 19" wheels.

The results are pretty much what you'd expect, which is that as you go up in size (and weight), 0-60 times suffer, but because of stiffer sidewalls and wider rubber in some cases, the lateral grip goes up.

Fuel econ suffers as you go up as well, but not as dramatic as HALF even with a +4 wheel/tire combo.

 

From my past experience, your mileage won't really change too much depending on what kind of driving you do.

I used to have a Jeep on 33" BFG's. If I was doing a lot of around town stop and go driving, mileage would suffer a little bit because it was more work for the car to get those bigger tires turning and up to speed.

However, during highway driving, you may actually see your mileage get a tiny bit better! Basically, for every revolution of the axle, your tires will move that little bit further with the bigger tires then with the smaller ones. As long as you're just cruising at highway speed without too much hard accelerating, you might actually see better mileage on the highway because of this.

 

I have an H2 with 35's. My mileage is 10.8 on average. You will not get 5 mpg with 37's unless you are driving up hill all the time. my mileage drops to 8 mpg. when i go over stevens pass. If you like the looks of 37's then go for it. We didn't by the cars for fuel economy to begin with ALso, I originally had 33's on it for the first year, my mileage according to the computer was the same as it is with 35's.

 

If you get a different tire with some idiotic tread pattern (super mud crawler t/a thornbird rock thompsons), it will reduce your mileage.

And annoy you to death with road noise.

 

I went from the stock 17" wheels to 22" on my escalade (but lower profile tires so the diameter is the same, which is obviously different than your situation) and my avg. mileage went from 14.5 down to 13.8 or so. I was expecting the difference to be much bigger.