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-   -   35''s and mileage/power (http://www.ramforumz.com/showthread.php?t=105553)

TheDon 02-24-2012 08:33 AM

35''s and mileage/power
 
I have a 2011 2500 HD Hemi with 4:10 rears. I'm going to a 35" tire and was wondering how much performance and mileage will be affected. I see everyone talking about a 4mph drop, but is that really possible? It is a big tire but once you get going on the road is it always fighting back? I can see maybe if there is a lot of stop go driving but I just can't see it being that big of an issue.

BLKSVT 02-24-2012 08:37 AM

I saw about a 3mpg drop with my 35's on...

TheDon 02-24-2012 09:44 AM

Quote:

Originally Posted by BLKSVT (Post 732153)
I saw about a 3mpg drop with my 35's on...

What gearing do you have?

BLKSVT 02-24-2012 09:51 AM

3:55 gear..........

augiedoggy 02-24-2012 10:32 AM

Quote:

Originally Posted by BLKSVT (Post 732212)
3:55 gear..........

thats your problem... with 35" tires and 3.55 gears you are puting a much higher load on your drivetrain and tranny the truck is working to hard to push you around...its just like going from the smaller sproket up front on a mountain bike to the largest...remember how much harder it got to pedal and move the bike... it took a lot more energy and power and burned you out faster...same exact concept here.. tires change your final gear ratio. thats why transmissions burn up so fast in that configuration...overdrive is usless because its already in overdrive while just in drive with that setup you lose your low gearing and the truck is constantly downshifting for more power.

I've see reports of people losing 20rwhp on a dyno after just going from 31 to 33" tires without changing the gears to match... imagine what youve lost... Its gotta be tough to get out of your own way?

I have 35" tires and 4.56 gears which are the closest to factory matched power ratio...I get about 12-13mpg with my 5.9 ext cab and 150k on the clock so...
aggressive mud tires also cost up to 3 mpg more than all terrain tires of the same size...

Raynval 02-24-2012 12:04 PM

I also have a 2011 2500 4x4 Hemi, but with 3.73 gears and traction aids front and rear. I have a 5" lift with 35" tires. I think 4.10 gears would be perfect for 35" tires, unless you pull heavy loads. With almost 400 H/P, 35" tires don't put any noticable drag on these motors. I never ran the stock tires, I had BFG A/T 33" (285/70/17) tires when I drove away from the dealership, so I really never knew how much MPG those cost me over the stock street set-up, probably 1-2 MPG. My speedometer was set at 33", which is the highest ours can be re-programmed to right now by the dealer (only OEM sizes and the Power Wagon comes with 33"). According to the on board computer, I was getting around 12-13 MPG with the 33" tires. Now with the 35" tires (Toyos M/T, which are one of the heavier and wider 35/12.5" tires) and the lift, the computer is showing between 10-10.5 MPG after a tank. If the computer was corrected it would be just a little better. So, I'd say my 35" set-up probably easily cost me about 4 mpg over the stock highway tires. From bad to worse. I've never really worried about MPG, but now with this truck and rising gas prices, it's starting to get my attention.

I also installed a straight through Magnaflow muffler, but really have not noticed any improvement in MPG.

Eventually I'll get a computer to correct the spedo and try different set-ups, it'll be intresting to see how much it helps.

Are you leveling, or putting any lift on with the 35" tires, is yours a 4x4?

TheDon 02-24-2012 02:18 PM

Quote:

Originally Posted by Raynval (Post 732303)
I also have a 2011 2500 4x4 Hemi, but with 3.73 gears and traction aids front and rear. I have a 5" lift with 35" tires. I think 4.10 gears would be perfect for 35" tires, unless you pull heavy loads. With almost 400 H/P, 35" tires don't put any noticable drag on these motors. I never ran the stock tires, I had BFG A/T 33" (285/70/17) tires when I drove away from the dealership, so I really never knew how much MPG those cost me over the stock street set-up, probably 1-2 MPG. My speedometer was set at 33", which is the highest ours can be re-programmed to right now by the dealer (only OEM sizes and the Power Wagon comes with 33"). According to the on board computer, I was getting around 12-13 MPG with the 33" tires. Now with the 35" tires (Toyos M/T, which are one of the heavier and wider 35/12.5" tires) and the lift, the computer is showing between 10-10.5 MPG after a tank. If the computer was corrected it would be just a little better. So, I'd say my 35" set-up probably easily cost me about 4 mpg over the stock highway tires. From bad to worse. I've never really worried about MPG, but now with this truck and rising gas prices, it's starting to get my attention.

I also installed a straight through Magnaflow muffler, but really have not noticed any improvement in MPG.

Eventually I'll get a computer to correct the spedo and try different set-ups, it'll be intresting to see how much it helps.

Are you leveling, or putting any lift on with the 35" tires, is yours a 4x4?


Jeez that scares me even more...I'm not feeling the gas thing whatsoever but I guess thats the price for our 4x4 vanity..lol. I think if you went with the 4:10 gearing it would help a great deal and also a tuner would help but they haven't made one yet for the 2011's.

I'm putting the Kore kit 3'' front coil spring and 1'' rear spring pack with Bilsteins all around.

StoneyWV 02-24-2012 04:17 PM

FInally people that understand gearing. i would think 4.56 and 35 inch should be about the same as stock setup, then your only penalty is the weight of the tires and rolling resistance if you go full aggressive.

And before the responses come pouring in, yes you 400hp HEMI will get you going with tall tires and 3.21 gears with no problem, but the MPG is the true indicator of whether your engine is working to hard or not.'

Just ordered my 4.11 to replace the current 3.55's. Can't wait until they get here.

candy08 02-24-2012 06:27 PM

There really is no replacement for gears. Wit these 4th gens, 4.56 gears and 37s is actually RT status. Granted you have more weight, but powerband wise...

http://i668.photobucket.com/albums/v...8/929dd3f0.jpg

Us 2011+ guys can get the Hypertech for time being to correct for new gears, our speedos, odo and scan for DTCs. It made a difference in itself getting the shift points back to stock and of course the speedo being correct is always nice lol

TheDon 02-24-2012 09:49 PM

Excellent responses here, lots of good tips and info. I will get the 35's but stay relatively small on the rim size to avoid unsprung weight as much as possible. An 18'' rim should be fine although a 20'' looks better IMO. My 4:10's are pretty torquey, I couldn't imagine what 4:56's must be like.


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