Hello and I'm new to lift kits but had had a couple of Cummins. The question that I have is I'm looking to add a 6" suspension lift to my 2012 2500 Ram 4x4. It has the EGR delete, DPF delete and I'm running a Smarty Sr. programmer. I have been told that by running 35' or 37' tires I will increase my fuel mileage by a couple miles or more. I will adjust my speedo for the new tires with the tuner. Then I have been told by lift kit installers that when I add the lift and the taller tires that my mileage will fall dramnatically. To counter this I will need to change my rearend gearing to makeup for the taller tires. I'm running the stock 3.45 gearing right now. Any help would be great. I'm not looking to drop a couple grand in the lift kit and then have my mileage bottom. I a grandpa driver and this truck is babied. It see's some offroad and snow but it will be mostly hard roads. Thanks.

 

Bump. Hope someone will chime in. I'm planning to lift my rig also.

 

Your fuel mileage will take a nose dive. Those tires are bigger and heavier increasing rolling resistance. Your engine will have to burn additional fuel to overcome additional rolling resistance and additional mass to keep them rolling. Your lift will also allow more air to pass under your rig, colliding with undercarriage components, further decreasing fuel mileage. Regrearing might help some, but you will still be in the negative with fuel mileage.

 

my 2012 3500 manual has a 6inch lift with 37's. ive got 3.42 ratio and im running around 20ish for highway mpg hand calculated

 

I lifted and reshoed and lost a lot of mpg's and truck got a little doggy. I regeared and love the low end and towing. I get about 17 if i keep it under 65. it's not a hight speed freeway queen. I built it so I could put most anything behind it.....

 

3.42s.....damn, I wish. But, I dont think that would work on my dually. Didnt that take away any torque?

 

I honestly thought id have to go down in lift or tire ( bought truck lifted ), but it has surprised me. Maybe cause of the manual. Torque wise it will get up and move pulling my boat or trailer ( about 7k ) and smoke the tires. Im happy will it so far but im not sure how it would do with 10k load

 

My 08. 6" lift 37x13.50 I get around 18. Hand calculated I also pull a 38' toy hauler no problem