Originally Posted by zabeard
but at the same time wont it help out my acceleration which will allow the engine to work a lot less, and would help gas milage, or is this just something that i think would work but its not. lol
No, because increasing the tire diameter has the same effect as installing a numerically lower gear ratio. By upping the tire diameter and
increasing the axle ratio by the about same multiplier, the overall relationship of engine RPM to vehicle speed remains about the same. That means that the torque applied at any given combination of road speed, gear, throttle position and engine RPM is about the same.
The whole point of changing the axle gear ratio is to make up for the torque loss caused by installing the larger diameter tires.
The issues of road friction, aerodynamic drag and tire mass are separate from the gear ratio calculation. No matter what you do, the larger/wider tires and lift create greater frictional losses that must be overcome by energy produced in the engine. Also, the additional mass of those big tires must be accelerated any time the road speed increases. For any given acceleration rate, the engine supplies more energy to the drive train to change the speed of the heavier tires.
And, of course, all of that energy comes from the chemical energy of the gasoline used.