Increasing MPG after installing lift and tires.

[ahallag88]

I will be the first to say I am no expert when it comes to vehicles. So… I have a few questions. I recently installed a suspension lift, wheels and 35” tires on my 21 night edition. While I knew it would effect my mpg quite a bit, I did not know it would be as drastic as it has. So first question is, what is a reasonable drop in mpg after installing? Second, what are some things I can do to assist in increasing mpgs a little bit? If it’s something I’ll have to live with? I’m okay with that because I love the look of my truck, but if it can be increased a little, I’d love that too.

 

[Idahoktm]

If you reprogram your speedometer, you'll gain back a couple mpg's.

 

[Alejandro_Andretti]

If you reprogram your speedometer, you'll gain back a couple mpg's.

Really? I’ve have my truck leveled on 285/6520 for over a year now without reprogramming. I’m getting 10-11mpg in California. Might have to reprogram

 

[Idahoktm]

Really? I’ve have my truck leveled on 285/6520 for over a year now without reprogramming. I’m getting 10-11mpg in California. Might have to reprogram

Yes. Your tires are 1.5" taller than stock, so your speedometer and odometer are not accurate and that effects how your computer calculates MPG's.

 

[theblet]

even after recal you will more than likely still be lower than before. 35” tires weigh a lot more

 

[Idahoktm]

even after recal you will more than likely still be lower than before. 35” tires weigh a lot more

Definitely.

 

[CalvinC]

Tires.

Weight, width, height, and tread.

Your best mpg was on the Prius tires your truck came with.

The more you stray from them in the areas above the worse mpg gets.

No magic cure unfortunately.

 

[ahallag88]

So

even after recal you will more than likely still be lower than before. 35” tires weigh a lot more

So would it be better to buy the reprogrammer/calibrator online or will the dealership or a auto shop do that?

 

[Shots]

The computer calculated mpg will be off, yes but as theblet noted you'll also take a bit of a loss too.
As for the calculation. If the stock tire is 32" and you install a 35" tire, you've increased roughly 9% in size. So your odometer and speedometers should be under reporting by roughly 9% as well since you're traveling further than the truck thinks you are. As a result a pre-mod mpg of 20 would reduce to a reported efficiency of roughly 18.3 mpg.
However you're likely to see worse than that because the added weight, resistance and/or torque will require the truck to work a little bit harder to reach and maintain the same speed as it did before. Another consideration is aerodynamic that are effected by the lift. These trucks are designed with some rake, which helps it from squatting when loaded, but that also has an effect on how the air is moving over the truck. So not only do the larger tires effect you mpg's but so does the stance.
Depending on the lift height and wheel/tire specs the loss will vary since not all of them are the same. Some tires with the same specs are a bit larger/smaller and different weights. Also some lifts still have a little rake while others are dead level. It kind of depends on what you have done, and I can definitely tell you a 6" lift hurts pretty bad when it comes to the wind.

All that said, it looks great, but I wouldn't be surprised if an unadjusted computer is showing 10 mpg, while an adjusted one is around 12 with a 6" lift and 35's.

 

[ahallag88]

Tires.

Weight, width, height, and tread.

Your best mpg was on the Prius tires your truck came with.

The more you stray from them in the areas above the worse mpg gets.

No magic cure unfortunately.

Correct. I knew I’d lose some mpg. But it’s been more than I thought.

 

[Shots]

So

So would it be better to buy the reprogrammer/calibrator online or will the dealership or a auto shop do that?

If you have a use for a programmer they can be worth the money. Some do a lot more than simply adjust the tire size. If you won't use any of the features it may be cheaper to ask the shop to do it for you. Although I'm sure who will do it, even though they probably all can.

 

[Louhound88]

I'm leveled with 35"s (295/65r20 Yokohama MT's). I have 3.21 gears so my mpg isn't completely terrible. Before getting my tire size recalibrated I would be around 12 to 15mpg.

After getting tire size corrected I typically average 17.5 mpg back and forth to work. Some days i'm up in the 18's, but I have a heavy foot and like to accelerate quickly so it's not too common.

I see you have 3.92 gears, so that'll be why yours are lower. If i set my cruise at 65mph i'll be in 8th gear bouncing between 19 to 22mpg. If i manually drop to 7th gear it'll be around 16 to 18mpg. Increase speed to 70 or 75mph and it just further spans out. I can ride in 8th gear at 75mph and can hover between 17 and 19mpg.

 

[Idahoktm]

So

So would it be better to buy the reprogrammer/calibrator online or will the dealership or a auto shop do that?

IMO, AlfaOBD is the best bang for the buck. My dealer was going to program mine, but it was going to cost about $150. AlfaOBD with a OBD2 reader and security bypass was $100.

 

[ahallag88]

I'm leveled with 35"s (295/65r20 Yokohama MT's). I have 3.21 gears so my mpg isn't completely terrible. Before getting my tire size recalibrated I would be around 12 to 15mpg.

After getting tire size corrected I typically average 17.5 mpg back and forth to work. Some days i'm up in the 18's, but I have a heavy foot and like to accelerate quickly so it's not too common.

I see you have 3.92 gears, so that'll be why yours are lower. If i set my cruise at 65mph i'll be in 8th gear bouncing between 19 to 22mpg. If i manually drop to 7th gear it'll be around 16 to 18mpg. Increase speed to 70 or 75mph and it just further spans out. I can ride in 8th gear at 75mph and can hover between 17 and 19mpg.

I would be extremely happy with 17-18 mpg.

 

[Shots]

IMO, AlfaOBD is the best bang for the buck. My dealer was going to program mine, but it was going to cost about $150. AlfaOBD with a OBD2 reader and security bypass was $100.

Seems like a pretty easy choice to me.

OP, just to be clear about the whole computer adjustment thing. This isn't actually improving your efficiency, it's just accurately reporting the mileage so your calculations are accurate instead of reading lower than what you're actually getting. You'll still be using the same amount of fuel.

 

[Mountain Whiskey]

Yes, as @Shots points out, you are not improving your milage by recalibration, you are simply getting a truer reading from the computer. Do the math by hand and see what your milage really is.

To improve milage:
1. If you tend to drive fast, drive slower.
2. Maintain proper air pressure in your tires.
3. Don't sit and idle too long, don't use remote start.
4. Make sure it is tuned up and running properly.

If those "The More You Know" BS answers from NBC don't do the trick, just drive less.

 

[theblet]

If the only thing you are going to do is recalibrate then just get the dealer to do it. If you plan on tinkering then it might be worth getting a programmer or alpha

 

[Idahoktm]

Yes, as @Shots points out, you are not improving your milage by recalibration, you are simply getting a truer reading from the computer. Do the math by hand and see what your milage really is.

To improve milage:
1. If you tend to drive fast, drive slower.
2. Maintain proper air pressure in your tires.
3. Don't sit and idle too long, don't use remote start.
4. Make sure it is tuned up and running properly.

If those "The More You Know" BS answers from NBC don't do the trick, just drive less.

He thinks he's getting 10-11 MPG because his computer is programmed for 32" tires. I don't think anyone here is so dumb that they think recalibrating the speedometer will actually give you better fuel economy.

Hand calculating won't do him any good, because his odometer isn't accurate. In order for hand calculations to work, he would need to factor in the reduced revolutions per mile.

 

[theblet]

Only way to know is to recal.

 

[ferraiolo1]

Op if you’re having to fuel up more often than before. That won’t change.

Only thing that will change with the recalibration is you will factually know how bad your mpg really is.


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