by jstrubberg » Mon Nov 05, 2012 1:46 pm
I drive a Jeep every day and am active on a couple of forums for modified Jeeps. One of the mistakes just about everyone makes is slapping a lift and larger tires on their rig without regearing the axles.
Any time you change the tire size, you change the final drive ratio for the whole rig. If you go to a larger tire, you force the engine to run at lower rpms at a given speed. What that translates to for an internal combustion engine is less horsepower and less torque. Your rig becomes anemic and your gas mileage falls through the floor.
My Jeep stock got about 18mpg. When I lifted it and put 35" tires on it, I dropped to 13.5mpg. I regeared and flashed the computer for the new gears and mpgs rose to 16.5. The rig also stopped searching for gears every time a headwind blew.
The more stuff I take along, the more time I spend taking care of my stuff!