Help for better MPG

[Scott Coburn]

I just purchased a used 2018 Chevy Silverado 4x4. It’s a 5.3L V8. It has a 7 inch rough country lift and 35 inch tires on 20 inch wheels. I’m getting TERRIBLE gas mileage (11.2 mpg) mixed highway and city driving (no towing). It has a 3.42 gear ratio (not sure if you need to know that or not). 

This is my 1st lifted truck and I’m reading others getting 16-20 MPG with the same set up I have so I feel like there’s something a miss with my truck. Maybe I’m wrong but seems I should get better than 11.2mpg.

Any help you can provide would be greatly appreciated!
 

[16LT4]

If you want better fuel mileage, pull the lift and tires. 

 

If you want accurate mpg calculations, correct your mileage driven (odometer) for larger tires. Left untouched, your odometer is underreporting.

[CamGTP]

Fork out the money and re-gear the truck if you want some of the MPG and drive ability to return.

 

It's on struggle street with those 3.42's, it's have to work way too hard just to get it moving and keep it moving. It needs 4.10's at a minimum but I'd go with 4.56 gears with those size tires.

 

I can't tell you how much it will improve but it will surely help with your mpg when it's not working as hard. Also you need to drive 65-70mph and not 80-90mph to get good mileage.

[Jacoby]

Guys with 7” lifts and 35’s aren’t getting 16-20 mpgs. If they tell you that then they’re lying. 

 

I got the exact same setup as you and had to regear my truck to 4.56 to get the mpgs back. 

[Scott Coburn]

14 hours ago, dukedkt442 said:

If you want better fuel mileage, pull the lift and tires. 

 

If you want accurate mpg calculations, correct your mileage driven (odometer) for larger tires. Left untouched, your odometer is underreporting.

The lift ain’t going anywhere. Can I have the odometer recalculated at most shops or is there somewhere specific I should go?

[Scott Coburn]

11 hours ago, Jacoby said:

Guys with 7” lifts and 35’s aren’t getting 16-20 mpgs. If they tell you that then they’re lying. 

 

I got the exact same setup as you and had to regear my truck to 4.56 to get the mpgs back. 

How much did switching out the gear cost you? Also, what kind of MPG are you getting now?

[Yondu]

57 minutes ago, Scott Coburn said:

The lift ain’t going anywhere. Can I have the odometer recalculated at most shops or is there somewhere specific I should go?

If the lift ain't going anywhere your MPG ain't either.  Some 32" all seasons would get you there....

 

Anyone saying they're getting 16-20 with a 7" lift and 35s is full of shit. Especially since your 4wd. 

 

Regear will give you a few mpg back, but you're over 2 grand since you have 4wd

[Yondu]

Also what 35" tire and how wide?

[Donstar]

17 hours ago, Scott Coburn said:

I just purchased a used 2018 Chevy Silverado 4x4. It’s a 5.3L V8. It has a 7 inch rough country lift and 35 inch tires on 20 inch wheels. I’m getting TERRIBLE gas mileage (11.2 mpg) mixed highway and city driving (no towing). It has a 3.42 gear ratio (not sure if you need to know that or not). 
 

I get this mileage when towing my travel trailer.  This gives some perspective on the amount of extra work required of your engine.  It will take a lot of gas saving to recoup the cost of re-gearing but will probably help with the longevity of your truck!  Pay now or pay later.

[Grumpy Bear]

Lift aside, 35's aren't just tall, they are heavy. Worse the bulk of the added weight is a long way from the axle. Flywheel effect. 

 

Swing a one pound weight on an 15" rope. Then try it with ten pounds on an 18" rope. Some of these wheel/tire combos weight fifty pounds more that stock. Changing gearing is like changing who's swinging the rope from Polly Purebread to King Kong. It is certainly easier for King Kong but the rope takes the same beating. It will feel better but the axle stress is the same. Will have no positive effect on braking. Will have a moderate effect on fuel usage. That's not an opinion. That's physics.

 

IMHO

[diyer2]

You want the look then you have to pay for it.

[Scott Coburn]

5 hours ago, Yondu said:

Also what 35" tire and how wide?

They are 12.5” wide M/Ts

[16LT4]

6 hours ago, Scott Coburn said:

The lift ain’t going anywhere. Can I have the odometer recalculated at most shops or is there somewhere specific I should go?

You could simply recalculate your mileage based on your measured tire size, with you’re fuel mileage being the same percent decrease as your tire diameter has percent increased. No, you won’t be to 20, but you may see 13-14. Not that it matters, because you’re paying the same for fuel no matter what mileage you calculate. 

[Yondu]

17 minutes ago, Scott Coburn said:

They are 12.5” wide M/Ts

Extremely heavy, very wide (lots of drag) and a MT tire for even more rolling resistance.  Add the 7" lift for terrible aerodynamics.   We are not trying to be jerks but you're never going to average 16-20.  Straight highway at 65mph you might touch 16 while cruising.  

 

It's why I did a under 2" lift with much lighter P rated 33 (11 wide) on a lighter all terrain tire.  I can get over 20 while on the highway, but I'm averaging around 16 with a fair amount of freeway time. 

 

35" MT tires is a look. There is no function for it, it's just a look some people like. That look will get you absolutely terrible mileage.  Go a 4.30 gear and you might get 12-13, but 10-11 is all you'll get for now.  

 

Non ethenol gas nets better mileage, but it's hard to find and costs so much more it isn't saving you money. 

[Jacoby]

8 hours ago, Scott Coburn said:

How much did switching out the gear cost you? Also, what kind of MPG are you getting now?

I think when it was all said and done it was $2250 to do a gear swap. 

 

If I slow down and run the speed limit I can average 18 on the hwy.  With the gearing though it’s hard to run less than 80 and that puts me around 15mpgs

 

in the city right now I’m averaging right at 13