While on the subject of tires I've often wondered if there is any advantage (fuel mileage wise) of 22.5 tires versus 24.5 rubber?

 

Yes there is an mpg advantage using LP 22.5 vs 24.5. First, LP 22.5, in most cases, have a lower rolling resistance than 24.5 tires. The selection of fuel efficient tires in 22.5 far excedes the selection in 24.5. While it is true, that at the same speed, with the same gearing, the 24.5 will allow the engine to operate at a slightly lower RPM and give the appearance of then getting better fuel mileage, you have to take into account the rolling resistance of the tires. Most 24.5 tires will have rolling resistance figures of 155 or even much higher, whereas fuel efficient LP 22.5 tires have rolling resistance of 110 or lower. The Michelin XDA Energy LP 22.5 drive tire has a rolling resistance somewhere around 90.

I guess it is just a matter of personal choice. Some like tall rubber while others are not so inclined. I like using LP 22.5 for the vast selection available and the decreased overall cost for tires and fuel savings. If one needs to replace a rim, 22.5 rims are easier, cheaper to come by than 24.5 rims since there are so many more of them out there. If it is all about running a certain speed and keeping the engine RPM lower, I would rather do that thru gearing than using taller rubber.

 

good info here http://www.bridgestonetrucktires.com...ctor_specs.asp
I am considering going back to l.p.22.5 from my current standard22.5 jsut to lower the height & get more stable a ride.