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Old 03-06-2012, 07:18 AM
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TheDon TheDon is offline
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Join Date: Nov 2010
Location: Cold Spring, NY
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Vehicle: 2012 6.7 cummins 2500 mega cab
Trim Level: big horn
Color: White
Engine: 2011-20?? 409ci (6.7L) Cummins Turbo Diesel 350hp 800lb/ft
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Originally Posted by Raynval View Post
Well it's hard to say about the RPMs, with the taller ratio (taller tires) there's more load (less mechanical advantage, gears are spread further apart, and the larger tires cause more drag) and the truck will drop a gear quicker (higher RPMs) and more often to try to overcome that load (or you have to apply more throttle which really sucks the gas). So, it really depends on the exact load and speed your going. But, I'd say that 35" tires are not going to get better MPG than the stock tires on the Highway, or in any condition I can think of, except for mud, where the stock tires are just spinning and your not going anywhere. Then they will really get better MPG!!

If your concerned about MPG, you probably want to stay with a A/T over a M/T, and might want to consider something narrower with a smaller contact patch, like a 285/75/17. Here's the best article I could find, keep in mind it compares a road tire with a A/T, it's even a lot worse with a high flotation tire.

I still think your gearing and 35" tires would work fine, although if your trailer is really that heavy, I'd be a little concerned, thats a lot of trailer for a gas motor. Do you have to pull it far? I pulled my Toyhauler the first time this weekend about 300 miles. I'm guessing my Toyhauler as loaded this weekend is around 5K pounds (smaller Toyhauler, no bedroom about 24'). It pulled fine, no problems. My computer said I was getting about 6.5 MPG, I hoped it would be better when I manually tested it. It wasn't, almost the exact same, 33.5 gallons for 220 corrected miles, or 6.57 mpg. 90% highway between 65-75 MPH (I need to slow down and get a little better MPG). Thats going to make for a tuff racing season this year.

Thanks Raynval, the study helped when they broke it down to the total cost at 15,000 miles, the 2mpg loss equates to $300 over 15,000 big deal, I'd rather have the 35's anyday LOL. The trailer I tow rarely gets to that 10K weight depending on the jobs I do and how much scaffold I need, but its maybe once a month or every other month and for no longer than 25-40 miles in distance. I towed yesterday about 25 miles and my MPG dropped 1 MPG according to my dashboard, 12.7 to 11.2. With those numbers its hard for me to think 35's alone will be worse than pulling a trailer and it has to be because of good gearing, 4:10's feel hardly anything.
2012 White Dodge ram 2500 6.7 Cummins HO. BDS 8'' long arm lift, Pure Performance track bar, FOX 2.0's, 20x10 Rockstars, 37" Toyo, BD steering brace, H&S tuner 175hp, H&S cooler delete, GDP Intake horn, boost tube & CCV delete, DPF/Cat delete, S&B CAI, AMP research steps. Timbren bump stops.
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