Gas mileage after 35s and 4 in lift

balaraform · June 30, 2020

New to trucks and lifts but noticed I went up to 35s with a 4in lift on my Sierra and dropped about 15% in mileage....roughly 3.5 mpg...is that a normal drop?

CamGTP · June 30, 2020

Yes.

You added a ton of rolling weight and made the truck even more of a brick going down the road.

topgear1224 · June 30, 2020

New to trucks and lifts but noticed I went up to 35s with a 4in lift on my Sierra and dropped about 15% in mileage....roughly 3.5 mpg...is that a normal drop?

If that's all you lost you are lucky!!!

I have a 2500HD 6 in tuff country lift.
On 315/75R16 9.7mpg highway mpg at GPS 70MPH
On 285/75R16 15.8mpg highway at GPS 70MPH.
Stock tire size is 245/75R16
This was the same highway loop same day for a full tank (24 gallons).

Anywho normal loss with a 6inch is about 25-30%.
With the smaller tires with the serria you did better than most.

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balaraform · July 1, 2020

About to go on an 800 mile trip wonder if I should put old wheels and tires on for the trip....now I’m wondering if I should of gone 33s instead....what y’all think?

CamGTP · July 1, 2020

33's or 34's would likely weight less than the 35's you installed so it would have helped some.

Lower your speed and the mileage should pick up. Doing 65-70mph is going to save on fuel instead of going 75-80mph.

topgear1224 · July 1, 2020

About to go on an 800 mile trip wonder if I should put old wheels and tires on for the trip....now I’m wondering if I should of gone 33s instead....what y’all think?

If you didn't regear it that's why your fuel economy is suffering. say you had 31 inch tires originally then you went to a 35 that's the same as Towing approximately 4000 pounds all the time. The only way to compensate that is to get your truck re geared.

the reason why my fuel mileage increased so much with a smaller tires is because my truck can't even engage 5th gear until 75 miles an hour with the 35s. And with aerodynamics like a brick it's working the engine much harder.

yes lighter tires will improve your fuel efficiency however you've already destroyed the aerodynamics of the vehicle by not only leveling it, but also lifting the front in 6 inches higher which means now there is 6in more air underneath to get turbulent which means more drag.

what can I say you got to pay to play

this is just part of owning a lifted truck. as the truck ages those heavy wheels and tires without a re gear are going to wear the engine and transmission out "sooner." (nobody knows longevity we could be talking the difference between 1 million miles and "only" getting 500k miles)

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topgear1224 · July 1, 2020

33's or 34's would likely weight less than the 35's you installed so it would have helped some.

Lower your speed and the mileage should pick up. Doing 65-70mph is going to save on fuel instead of going 75-80mph.

As far as I know nobody has a gauge recalibrator so if he's doing 70 on 35s showing up on the speedo he's actually going much faster!!!

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balaraform · July 1, 2020

Getting the hyper tech speedometer calibrator tomorrow should that help?

CamGTP · July 1, 2020

Other than HP Tuners which would cost $1,900 at a minimum I too do not know what is out there exactly. Maybe that hypertech thing does work on the new trucks.

The new T1 trucks are a whole different ball game when it comes to tuning.

Edited July 1, 2020 by CamGTP

topgear1224 · July 1, 2020

Getting the hyper tech speedometer calibrator tomorrow should that help?

If it actually works it'll make the gauge accurate.

If you're doing the speed limit on your big tires you were likely six to eight miles an hour faster. (I didn't actually calculate it)

That's easily 10% loss just due to the speed

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topgear1224 · July 1, 2020

Other than HP Tuners which would cost $1,900 at a minimum I too do not know what is out there exactly. Maybe that hypertech thing does work on the new trucks.

The new T1 trucks are a whole different ball game when it comes to tuning.

I should be clear if you're going off of your trip meter your trip meter is no longer valid once you put oversized tires on. Not until there's an ECU crack.

The little tie in modules do not affect the trip computer data they only affect the needle on the speedo.

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CamGTP · July 1, 2020

It''ll be a long time before something becomes cheaper than HP Tuners because they have to give you a new unlocked computer to tune 2019+ T1 trucks. I'll stick to tuning the earlier years for now, it's much easier and cheaper.

balaraform · July 2, 2020

So update after drive....

800 miles a few weeks ago with stock 275/60/20. Avg 18.9 mpg speed around 73

tonight 800 miles 35/11.5/20 nitro ridge 4 inch sst lift (which looks great I’ll post some pics once I clean the car from the billion flies once I hit the Michigan border). 16.8 mpg avg speed around 75

not as bad as I thought for hwy, in town more like 14-15 before was 17....

putting the Hypertech on tomorrow when it gets to the in-laws and I’ll update after the ride home.

thanks for all of your insight!

rikhek · July 6, 2020

On 6/30/2020 at 7:56 PM, balaraform said:

About to go on an 800 mile trip wonder if I should put old wheels and tires on for the trip....now I’m wondering if I should of gone 33s instead....what y’all think?

You might consider the fact that gas is damn near free at current pricing so the minimal $ differential is negligible for many. Your savings would be pennies....