[QUOTE=circmand;133354]
Quote Originally Posted by twistedsymphony View Post
Theoretically larger rolling diameter will increase highway MPG... the reason is because it changes the ratio of RPMs to tire rotations such that your engine doesn't need to spin as fast to go the same speed.

the down side is added weight which means it takes more energy to build momentum (eg: stop and go city traffic mileage would be worse).


I get that but once you decide on the tire size it seems to me max inflation is the way to go because you get max diameter, minimum rolling resistance and the air dowsnt weigh anything. Or am I missing something?

Basically, the added weight from oversize tires comes from the simple fact that there is more material rubber required to manufacture the bigger tire (more rubber material = more weight).

Remember, it takes "x" amount of energy (gasoline), to move "x" amount of weight (in this case wheel & tire). The ideal solution in gaining maximum MPG with tires & wheels is to run the "tallest" tire that will fit (maximum O.D. = lower engine RPMs for same speed); at the "max PSI" (per sidewall label = least rolling resistance); with the "narrowest" available tread (low section width = less drag); mounted on an all aluminum lightweight wheel like CenterLines (reduced wheel weight = reduced overall weight). Thus, having said that-- an example of the most "economical" tire & wheel combination to mount on the VX is the TOYO - Open Country A/T in 255/70R18 (32.1" O.D., only 10.3" wide, weighs only 41 lbs) and mounted on lightweight aluminum wheels (such as Centerlines).