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MPG with 37” tires?

DavisBrookshire

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I work at an FCA dealership so I picked up a 2019 Bighorn Quad Cab 6’4” bed 5.7 Hemi with normal rear end and I was wondering what kind of MPG y’all were getting with big tires. I’m getting 19-20 highway and 16 city. Will probably get a higher end trim if I plan on dumping money into a lift, rims and tires.
 

speedbyu

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Would say it also depends on your gearing. If you have the 321 gears you will probably not like the 37's because the acceleration you have will be greatly diminished but might lower your rpm's at highway speeds enough to get better than 20 mpg. 390 gears might maintain stock mileage because the difference in tire height and the truck will accelerate nicely.
 

Willwork4truck

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Would say it also depends on your gearing. If you have the 321 gears you will probably not like the 37's because the acceleration you have will be greatly diminished but might lower your rpm's at highway speeds enough to get better than 20 mpg. 390 gears might maintain stock mileage because the difference in tire height and the truck will accelerate nicely.
For sure see if you have 3.92 or not. I'd think the truck would feel a bit sluggish with that tire size and 3.21's.
 

SilverSurfer15

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Minimal trucks running 37s, but your mileage won’t bust 13-14. Probably 11-12, and the truck will drive awful with 3.21s at least at highway speeds. As stated, 3.92s or bust for 37s. Hell for 35s too.

A lot of it depends on the wheel and tire as well, a lighter AT on a 20x9 will definitely drive better than say a heavy/aggressive MT with 10-12 inch wheels.
 

Troublemaker

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I work at an FCA dealership so I picked up a 2019 Bighorn Quad Cab 6’4” bed 5.7 Hemi with normal rear end and I was wondering what kind of MPG y’all were getting with big tires. I’m getting 19-20 highway and 16 city. Will probably get a higher end trim if I plan on dumping money into a lift, rims and tires.
I have a 2019 with Mopar 2" lift, Mopar rims, 35" tires and 3.92 rear axle. 4000 miles now and best highway MPG is 13.7, city no idea. Adding a K&N tonight as going on a long haul this weekend and curious if will improve at all. I had hoped the large tire would offset the 3.92 axle ratio and keep decent MPG, but it is what it is a lifted truck with big tires... New to site, thought would share.
 

Helmetface

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I have a 2019 with Mopar 2" lift, Mopar rims, 35" tires and 3.92 rear axle. 4000 miles now and best highway MPG is 13.7, city no idea. Adding a K&N tonight as going on a long haul this weekend and curious if will improve at all. I had hoped the large tire would offset the 3.92 axle ratio and keep decent MPG, but it is what it is a lifted truck with big tires... New to site, thought would share.

Highway is 13.7? That ain't right.

What tires?

Most are posting 15+ on Nittos for example.
 

SilverSurfer15

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Highway is 13.7? That ain't right.

What tires?

Most are posting 15+ on Nittos for example.

Agreed, seems low. Running 70ish, I can get about 13 on the 325s, and about 16 on the 35x11 terra grapplers.

I should add, this is in favorable contains. Toss in some wind and rolling hills and it’s alllllll over lol.
 

mobius0034

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I should add I have 3.92s and it drives fine. it does shift to 7 on hills were it wouldn't of before. but overall drives excellent. ride amazing, same as stock and just as quiet.
 

SilverSurfer15

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While my truck hopes to get 13 on the 325s, it actually does around 15 on my other 35x11.50 Terras. It really just depends on the weight, tread, width, etc that all adds to the general rolling resistance.

I’m about to drive this thing 1700 miles round trip, so it will be interesting to see how it does.
 

mobius0034

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Leveled

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I’ve got 20’s with 35x12.50’s, a Pro-Comp level and 3.92’s. It was done by the dealer before I bought it. They also had the speedometer calibrated. I average about 17.5 mpg on my trip to work which is mostly highway with speeds ranging from 65 to 75. On a long highway trip I’ll average over 18. People who are seeing big drops in MPG’s may be partially due to a lack of speedo recalibration.
 
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