Thanks for all the help and advise. Yes I have regeared to 5.13 and have done every engine mod I have heard of like cold air intake, a viper throttle body and a Hypertech programmer. I get better gas mileage than most considering I run AT's most of the time. I have a set of MT's for just offroad use but I have used my AT's in Moab and they ran great. That's why I am worried about MPG, i drive it long distances. Guess I hoping that since the tires had Kevlar in them they would be a lot lighter. Yes weight is everything when you consider MPG. But it's a Jeep not a hybrid. Anyone know of a site that will give you a comparison of tire weights?