Drop tires height back to stock or go up to 4.10 gears

[KevinD]

I'm wanting to get the best mph for my truck. Considered going to 3.42 ppl suggest not to do that. Some one sent me a calculator and the best gear to run with my truck it said 4.22 but closest to that is 4.10. But with 3.73's and 34 inch tall tires I run 1800 rpm. But if I went back to stock or went down a gear to 4.10's my rpms would be right at 2000 or a little more. But some some brought up spooling quicker. So can someone give me a hand in this? Which would be better for fuel. And what does spoiling quicker help with mpg or does it not? I thought to much boost made worse mpg. Thanks for all that reply.

 

[Verlon at ATP]

If you are looking for economy, you want your usual cruising speed to be in the 1800-2000 rpm band. You will get better economy with smaller tires in that rpm band than you will with larger tires in that rpm band.

Big tires and fuel economy don't mix.

 

[Chevy1925]

did you physically measure the outside diameter of your tires? dont go off what the numbers on the side say, you would be surprised how far off they are.

the 2000 rpm will be better for towing spool up and towing mpg but it wont help your unloaded mpg. 1800 rpm is the better for your unloaded mpg but not towing (specially if you have hills). i went from 1800rpm at 70mph to 2100rpm at 70mph when i swapped gears. it made in town mpg go up, highway suffered a bit unloaded but towing i saw a 1 mpg gain. no tuning changes other than for my speedo.

at 1800 rpm, you should still be able to light that stock turbo easy, it jsut wont come on as quick at 2000 rpm. i can light my stock one as low as 1400-1500rpm.

 

[KevinD]

No I haven't measured them yet but I know they are a lot bigger than stock. Thanks for the info. I drive a lot on the interstate unloaded to and from work. So I was curious. So I should drop back down to stock height tires? Also I know the 20's are not helping the most but do I need to get rid of them also??

 

[KevinD]

Also why gears did you go to?

 

[Chevy1925]

So I should drop back down to stock height tires? Also I know the 20's are not helping the most but do I need to get rid of them also??

Can't answer those questions for you. I regeared mine to fit my use of the truck. All I can give you is my real world facts and you choose from there. You have to choose what you feel will suit you best

Also why gears did you go to?

Well I'm on 37s (measure 36.5" tall) and I went from stock 3.73s to 4.56 gears

 

[TheBac]

Why did you start another thread about the same subject? Expecting a different outcome? Not going to happen.

Best mileage is from a stock truck, stock or mild tune, stock or near-stock tires, and around 2000rpm. If you cant figure it out from that, then there's nothing we can tell you.....

As Verlon said, you cant have both.

 

[Hot COCOAL]

I went to 4.11's to get my gear/final drive ratio back to stock like #'s running 35's and I wanna say with these gears I turn about 1850rpm @ 60mph...

On my last extended mile freeway drive (2300mi round trip) I averaged as much as 18.6mpg on a tank of fuel (hand calc'd) which I think is pretty good considering its a lifted crew cab with 60 over injectors and its always in the kill tune, and Im running 34.8" x 12" A/T tires on 18x10 forged wheels

Also, when I bought the truck the DIC said 11.8 and it was pretty dang accurate
It was sittin on 18x9 chrome wheels shod in 33x12.5 MT's and the front end was cranked
Lol

I do think areodynamics plays a role in fuel economy as well, our trucks arent exactly role models in the wind tunnel to begin with, so if youve got the rig leveled with no rake from from to back throw the idea of attaining better MPG out the window

 

[KevinD]

Can't answer those questions for you. I regeared mine to fit my use of the truck. All I can give you is my real world facts and you choose from there. You have to choose what you feel will suit you best




Well I'm on 37s (measure 36.5" tall) and I went from stock 3.73s to 4.56 gears

Basically you regeared yours to be like stock with you tire height. Maybe alittle lower.

 

[KevinD]

Why did you start another thread about the same subject? Expecting a different outcome? Not going to happen.

Best mileage is from a stock truck, stock or mild tune, stock or near-stock tires, and around 2000rpm. If you cant figure it out from that, then there's nothing we can tell you.....

As Verlon said, you cant have both.

Your right. I did start another trend hitting around the same subject but with a different question. The only reason why was wanting to get more ppl commenting on and different opinions from ppl. Not looking for different result just reaching out there for ppl who did see my last tread. And your right trying to get different results isnt going to happen but the more ppl tell me there results helps me understand and decide more of what I want to do. That's why I asked about dropping to 4.10 or going back to stock height. so the way I see it I can go to stock height tires and gonna keep my 20's on the truck. I know you can't have both wasn't looking for both since I drive my truck everyday. You see my truck use to sit on the yard and never drove it unless I was home because I flew to work and had a company truck but now since I took a job back south i drive to an from now so looking to what needs to be done to help me in the long run.

 

[bfmine]

Fwiw I run 35s on stock gearing and at 2000 rpm I'm at around 90
I also have the 6 speed I try not to pay attention to fuel mileage 20-22 highway if I can behave

 

[KevinD]

Fwiw I run 35s on stock gearing and at 2000 rpm I'm at around 90
I also have the 6 speed I try not to pay attention to fuel mileage 20-22 highway if I can behave

Do you have the conversion of a 06 and up? Or is it standard

 

[KevinD]

Or*

 

[Tyler_LBZ]

With 34" tires your stock gears are probably best, the money you will spend re gearing will be a lot compared to a very small if any increase in mileage.

What kind of mileage are you getting? I am running roughly 33" tires and on my hottest tune I get between 20-22 mpg highway and my rpms are well under 2000. Your tuning could make a difference on mileage not just the tires or gears. I have always gotten better mileage on my biggest tune on the highway than my lower tunes.

I realize you have a 5 speed, I'm just curious what your getting now for mileage.

 

[NinjaMax]

I ran 4.56's with 37" tires for a couple years, I thought they sucked for a lot of highway driving, however around town and towing I loved them! If I could do it all over again it would be the same route cocoal went, 35"s with 4.11 gears

 

[Ridin'GMC]

I ran 4.56's with 37" tires for a couple years, I thought they sucked for a lot of highway driving, however around town and towing I loved them! If I could do it all over again it would be the same route cocoal went, 35"s with 4.11 gears

The reason it sucked for you is because you have a 5 speed. IMO, 4.56 is for 37" tires is better on the 6 speed and 4.11 for the 5 speed for daily driving. I'm running on stock gearing on my 37's, I have to leave it in 5th for highway driving unless I'm in the mode for driving 75 or more. 4.56 on 37's is perfect for towing for the 5 speed guys, and it will give me better towing drive ability for my 6 speed because tow/haul mode leaves me in 5th for highway driving.

 

[NinjaMax]

The reason it sucked for you is because you have a 5 speed. IMO, 4.56 is for 37" tires is better on the 6 speed and 4.11 for the 5 speed for daily driving. I'm running on stock gearing on my 37's, I have to leave it in 5th for highway driving unless I'm in the mode for driving 75 or more. 4.56 on 37's is perfect for towing for the 5 speed guys, and it will give me better towing drive ability for my 6 speed because tow/haul mode leaves me in 5th for highway driving.

I completely agree, the worst part about a 5 spd on 37"s with stock 3.73's was mountaun driving, at least the climbing part. Seemed like the sweet spot at 65 mph was to slow for 5th so my egts got up there, so I was constantly bumping the throttle to downshift to cool things off. Loved the flatland interstate tho

 

[Chevy1925]

I completely agree, the worst part about a 5 spd on 37"s with stock 3.73's was mountaun driving, at least the climbing part. Seemed like the sweet spot at 65 mph was to slow for 5th so my egts got up there, so I was constantly bumping the throttle to downshift to cool things off. Loved the flatland interstate tho

Nailed it. Specially when towing. Unloaded or loaded I run 70mph so runnin down the road unloaded at those speeds doesn't really affect me like those that like to go faster. When I was on stock gearing, that was the speed I got the best mpg at and I've since just grown accustom to driving that speed lol

 

[KevinD]

Really depends on hoe heavy my foot is the last couple days I have been noticing running right around 2000 rpm my truck has seen to get better than when I cruise around 65-70 seems like making it shoot up a couple more hundred rpm is helping it not with34's. But any where from 16-19. Before the 20's I had 285/75/16 and I was getting about 21-22 at cruising. I usually cruise everywhere I go. But been testing it the last few to see mileage change.