Performance gain from smaller tires.

[mb1]

So I'm planning on replacing my 35" toyo MT with some 265/70/17 for the winter, and also removing my lift in favor of a somewhat lowered look, similar to a chev 2wd 1/2 ton.

I haven't weighed the tires but I think the 265's ( toyo M55 ) have to weigh at least 20# lighter per tire. Plus they're about 2" narrower and 3" shorter.

Anyone think I can gain 3 mpg out of this? Maybe I'll have to remove the lift as well to push less air for the full benefit.

Haha right now I have to go 145 kph to get up to 2000 rpm in 6th.

EDIT: Truck is an LBZ Duramax CCSB, currently I get about 15 USMPG mixed driving.

 

[AreWeThereYet]

Why the M55 do you drive lots of gravel? That's why I have them on my service truck.

 

[Cyle]

3 MPG? Yea right. I lost MAYBE 1 MPG when I put my 6" lift and 37" tires on. That is on my Dodge Cummins, but tires and lift won't change MPG THAT much. Infact if you get some big AT you'll see better MPG on the highway, because of the lower RPM's. I'm not overly familiar with the duramax but i'm sure you get a lot better MPG at 1800 RPM then say 2200 RPM. Aggresive tires take that away, but big AT's are good if you want the highway MPG. Part of your problem might be those toyo's, probably the worst MT tire i've ever ran in more then one way.....

And lowering a 4x4, that should be forbidden

 

[Shredder]

My '08 Super Duty got around 19l to 100 kms with a 6" lift and 35 x 12.50's, 3.73 rear end. I traded it in on an '09 Cabelas Super Duty with 285/75/18's and just a level kit; 3.55 rear end. Now I'm at 13l to 100 kms. The lift and tires makes more of a difference than alot of people are willing to admit. I was told before that on diesels it wouldn't make a difference; it does.

 

[Cyle]

My '08 Super Duty got around 19l to 100 kms with a 6" lift and 35 x 12.50's, 3.73 rear end. I traded it in on an '09 Cabelas Super Duty with 285/75/18's and just a level kit; 3.55 rear end. Now I'm at 13l to 100 kms. The lift and tires makes more of a difference than alot of people are willing to admit. I was told before that on diesels it wouldn't make a difference; it does.

Is that hand calculated or the lie-o-meter? I have no doubt my 6" lift and 37" mud terrians tires are stealing some mileage. A tiny bit due to increased height and more power to turn on the highway, but it hasen't droped more then about 5%. As for in the city the bigger tires take more power to get moving, and have more rolling resistance so a bit is lost there to. However throw the stock size tires in mud terrains and you'll see a bit of mpg drop to. Heck though, a manual vs auto, or even 2wd to 4x4, longbox crew cab to single cab effects MPG probably as more or more then a lift and bigger tires (to a point). Your change in gear ratio is a huge difference. Big difference if you were comparing the SAME truck, as even two identical trucks can vary in mileage.

If I cared about MPG I wouldn't of just bought a Road armor bumper, bigger lift and bigger tires I will still spend less money on fuel then the gassers.

 

[08summit]

Is that hand calculated or the lie-o-meter? I have no doubt my 6" lift and 37" mud terrians tires are stealing some mileage. A tiny bit due to increased height and more power to turn on the highway, but it hasen't droped more then about 5%. As for in the city the bigger tires take more power to get moving, and have more rolling resistance so a bit is lost there to. However throw the stock size tires in mud terrains and you'll see a bit of mpg drop to. Heck though, a manual vs auto, or even 2wd to 4x4, longbox crew cab to single cab effects MPG probably as more or more then a lift and bigger tires (to a point). Your change in gear ratio is a huge difference. Big difference if you were comparing the SAME truck, as even two identical trucks can vary in mileage.

If I cared about MPG I wouldn't of just bought a Road armor bumper, bigger lift and bigger tires I will still spend less money on fuel then the gassers.

X2 Bigger tires and a lift may change your fuel consumption by a 1MPG in a Diesel and thats about it...as for getting 13l/100km in that Ford Thats incredible...lol...How fast you driving that thing 80km/hr with a tailwind.

 

[Cyle]

X2 Bigger tires and a lift may change your fuel consumption by a 1MPG in a Diesel and thats about it...as for getting 13l/100km in that Ford Thats incredible...lol...How fast you driving that thing 80km/hr with a tailwind.

O ya I forgot to mention the FORD is the biggest problem

 

[Shredder]

X2 Bigger tires and a lift may change your fuel consumption by a 1MPG in a Diesel and thats about it.

I beg to differ. We all ran lifted trucks for the past 3 years, and now all run stock or level kits. 1 Dodge, 1 Chevy, 2 Fords. The Dodge did a bit better than the Fords. The Chevy did a bit worse than the Fords, and spent the most time in the shop getting it's suspension/front end repaired. We all operated in the same field, and drove the same kms daily. None of us came in anywhere near 1 MPG with our lifted trucks of what we get now. Running 3.55's puts me at 1400 RPM @ 110kms/hr, and I'm also running 32.5" Mickey Thompson ATZ's instead of the ProComp 35" Mud Terrains I was before.

 

[mb1]

Well I reset the lie-o-meter on the way home from work today and it was showing an even 10L/100km when I got home. So even when you factor in the 10% difference due to not being adjusted for the smaller tires.... 10L + 10% = 11L / 100km. That = 21 US mpg. My best ever tank was last summer highway only going east I got 18 usmpg.

Considering we're running winter fuel now, and I was going about 120 ( corrected) on the way home, I think I'll be able to get some good mileage next summer.

I'm getting my programming updated here pretty soon, so I won't be able to compare apples to apples completely. I'm also hoping to fab up a ram-air type of mod to my airbox.

From guys I know it seems like the Dodges definitely do better with the bigger tires not affecting mileage as much. With the 35's on I think I was lugging the engine a little bit, it would just shift into 6th at 65 mph. I had to go 140k to reach 2000 rpm.

 

[GasCan]

My lie-o-meter had me at 20.1/100 yesterday when pulling my trailer down to the US border and back. Went there empty with a strong cross wind, and headed back with one bike in the trailer and same cross wind turning to headwind.

I run Fun Country II 285/70/17 tires and they work well on my 4" Rancho lift. I am switching to a Toyo 305/75/17 on Monday to gain more load rating from the tires. That will take a lil trimming with my 4" lift but should work well. Doubt i'll see any significant loss in mileage with the larger tires.

Currently 17.5mpg on the highway when easy on the boost and 12.5 when towing. That drops by 1 mpg if I push on it and that's running 33.5's.

 

[kimwin]

toyo mt's to bf's i gain easily 3mpgs empty

 

[powder junkie]

bigger tires and lifts obvioiously affect fuel mileage. thats a no brainer. diff trucks vary tho. sum worse than others. and in terms of running a big A/T instead of a M/T and gaining mpg over a small tire......pffft id like to see those results haha.

 

[dezmitchell]

Im running 35" Dick Cepik M/T's .....Will i get a worth while MPG gain if i switch to something like a Pro comp A/T(would still be a 35")? Noise dont bother me, always have a the radio up.

 

[mb1]

Im running 35" Dick Cepik M/T's .....Will i get a worth while MPG gain if i switch to something like a Pro comp A/T(would still be a 35")? Noise dont bother me, always have a the radio up.

The only way I could see you gaining anything would be to go to a highway tire like the Dura grappler or something like that, but I think it would be minimal at best.