Lift/tires/performance/mileage

[seansharley]

OK, I understand this is about give, and take, but.... I had a 3½RC kit installed with 305/55/20's. I was expecting some changes, and loss, but 5mpg on the highway for someone that drives 25k+ a year adds up. I hated the stock look, and wheels, and love the new look. The truck hits hard over speed bumps, and I would love to correct it somehow, and do some bolt ons (if possible) to get my mileage, and performance back. Any suggestions?

[fondupot]

Take off the lift and tires. Boom performance and mileage increased. You wont gain back the mileage and performance with simple bolt ons.

[high country]

I always say you wanna play you got to pay. I am in the same boat so I will live with the look and keep the mileage, besides it rides nicer with a short 1 inch level.

[Spurshot]

Skinny short tires and lowered will be the best mileage and acceleration. Ask yourself what makes you happier.

[amxguy1970]

OK, I understand this is about give, and take, but.... I had a 3½RC kit installed with 305/55/20's. I was expecting some changes, and loss, but 5mpg on the highway for someone that drives 25k+ a year adds up. I hated the stock look, and wheels, and love the new look. The truck hits hard over speed bumps, and I would love to correct it somehow, and do some bolt ons (if possible) to get my mileage, and performance back. Any suggestions?

 

Did you remove the valence? What tires did you get? Are they load range E? Also did you change wheels to something larger? Finally what gears are you running? That will tell us pretty much all the difference...

 

Tyler

[seansharley]

No, didn't remove the valance, running nitto terra graps Lt, load range E. XD 20X9's. Had 20's on it from GM. 6.2, with 3.42

[blackout07]

Tune and deal with it. If you were at all concerned with mpgs, you should've never lifted it. Welcome to the world of lifted trucks.

[seansharley]

So, I'm assuming a tune, CAI, exhaust mod doesn't increase performance, or mpg, as everyone claims? That's the info I was curious about

[Stevens03]

Well my first question is are the tires bigger in diameter than your stock tires? If so, your mileage drop may not be as bad as you think. If it was me, I'd have Blackbear do a custom tune for your truck and see where your mileage falls. If it doesn't go back up, then I'd consider a different tire size. My last truck with 305's on it didn't take that big of a hit with 20's I lost maybe 1-2mpg after all things were considered.

 

Doing some math shows the new tires are 1.65" larger than stock. IF your not programmed for them, your mileage is lying to you. Get that fixed and report back.

[Spurshot]

I think most people know their speedometer and DIC mileage will be off with a change of tire diameter and calculate their mileage.

[fondupot]

So, I'm assuming a tune, CAI, exhaust mod doesn't increase performance, or mpg, as everyone claims? That's the info I was curious about

 

my tune didnt even increase mileage on a stock truck. Its about the same. but I have more power and better driveability.

 

Like i said, simple bolt ons, including tuning, will not regain your mileage and performance of a stock truck.

 

But a tune will help correct the computer to compensate for the bigger tires. Like Stevens14 said, you may not be getting as bad of mpg as you think, its just the computer is still set for stock sized tires. So it thinks you aren't going as far on the same amount as gas. The bigger tires will travel further in one rotation compared to a stock sized tire.

[MTB]

Wheel/tire weight will impact MPG more than you think. Side Wall Height will greatly improve comfort-ability. I went down this road with my 2007. It had 20's on it and it road rougher than a log wagon. Over time as I increased lift and sidewall height the ride became more bearable. However as this occurs the MPG goes in the toilet. IF you like the height and look of the truck with the lift consider changing wheels and tires to something that weighs less. Go to an 18" Wheel, this will give you a taller side wall, more cushion. Specifically look for tires and wheels that weigh less, much less than what you currently have. It all boils down to rolling resistance, and how much energy it takes to get the tires rolling and keep them rolling. It is a matter of physic. Aerodynamics fall next in line. Put a bed cover or topper on it to reduce the drag on the back of the bed. A tune should also be considered to re-compensate for the different tire size.

[TJay74]

I think most people know their speedometer and DIC mileage will be off with a change of tire diameter and calculate their mileage.

 

 

How do you calculate this when the odometer is off. Until you correct the calibration there is no way to hand calculate the mileage to find out how bad the hit is. 1st thing you have to correct the calibration, then you can hand calculate the mileage at fill up to see the rear numbers.

[MTB]

 

 

How do you calculate this when the odometer is off. Until you correct the calibration there is no way to hand calculate the mileage to find out how bad the hit is. 1st thing you have to correct the calibration, then you can hand calculate the mileage at fill up to see the rear numbers.

Use a GPS like a Garmin or a phone app to calculate distance. I think there is even a phone app that does a heads up display for MPH. Drive a known route recording your start and ending miles. This should give you a fairly good idea of what the difference. This can then be applied to your calculations.

[Bmotoman]

 

 

How do you calculate this when the odometer is off. Until you correct the calibration there is no way to hand calculate the mileage to find out how bad the hit is. 1st thing you have to correct the calibration, then you can hand calculate the mileage at fill up to see the rear numbers.

Multiply the mpg on the DIC by (D_new/D_old) where D_new is the diameter of the new tire and D_old is the diameter of the old tire.