[timgco]

You are getting better mpg than what is shows on your dash. Teh 37's throw it off a little. If you have the full height GOBI you will notice about 1 or 2 mpg difference...unless you have the tire mount, tool boxes, fuels cans, and all that stuff up there.

Sinc eyou have an older truck, it may be time for a good tune.
I ran teh superchips on my last H2. You can adjust for your tire height and change the shiftpoints. Those 37's, although not much bigger than your almost 35" stock tires, will cause your truck to shift more up longer grades and shifting in and out around town or cruising around 55mph to 60mph. That $400 Superchips programmer helps with that quite a bit.

Check your tire preassure too.

Good luck.