I have an '06 Cummins 4X4 Quad Cab with 373's and I'm getting 21 on Highway. I'm thinking about going to 285's if I can do it without hurting my MPG. When you changed tires how did your mileage change? What tires did you have and what tires did you go to? I pleased with my mileage butwill gladly listen to somebody that offers ideas on getting better MPG's. Thanks and Glad to be on the Forum.

 

You should get better mileage as the wheels will be turning faster @ less RPM

 

if you are running mostly highway, your mileage will improve slightly. alot of city driving will cause your mileage to go down due to stopping at starting a larger wheel.

I'm about to find out how much of a change going from 265's to 315's will net me.

 

I went from 245/70/17 to 305/65/17 and do mostly highway driving. I saw hardly any change at all in mpg. If I lost anything it was less than .2 mpg. Definately more loss if you do a lot of stop and go driving though.

 

I'm running the pro comps as well and I think my mileage has increased just a little after losing the BFG 285s.

 

Will the 305/65/17's fit on stock wheels without rubbing?

 

yes

 

I'm about ready to put 285's on hopefully this week. I'll let you know in a week or so how they effect my mileage.

 

Absolutely no rub. Maybe off road during hard flexing it might. Haven't had the opportunity to find out, but I don't think it would even flexing.

 

I should say they fit the stock rims as long as you don't have the steelies. They aren't wide enough for the 305s to mount on. If you have the upgraded stock wheels, they fit fine.