Im running 35" micky thompsons with a 2.5" level kit, aftermarket flares, and mud flaps front and back, no rubbing at all with plenty of clearence on 20" Fuel Hostage wheels with a +1mm offset.

 

How big of tires can you get before you loose MPG on the highway? I have a 2012 cummins, auto, 3:73, mini maxx, deletes, 4" turbo back.

 

My tires are 34.40 or 35s but i hear your ratio goes from 3.73 effectively to about 3.55 so rpm drops down. But i think it does get alittle worse you may drop about 2mpg to about 17. I think it has alot to to with an increase in rolling resistance. I would also experiment with tire pressure. Or look at a narrow tire.

 

35s with leveling kit no rubbing.

 

I have 35-12.5-17 Toyo Open Country MT's on stock rims with a 2 inch level kit in the front. If you rub a bit, you'll have to adjust the control arm bolt (not sure of the name) to get the front tires to sit in the middle of the wheel well correctly.

 

315/75/16's on Stock Wheels

Luke