38's on M1008= Better Gas Mileage?

[Hartinarmz]

I have been researching alot and just wanted to clarify as to this theory I have been hearing. Do bigger tires in fact raise the highway mileage of an M1008? I am wondering because the vehicle I purchase will be a DD and I am debating between the M1009 or an M1008 with minimal lift and 38's. I would also be putting the sidewinder kit on either vehicle that I get. Sorry for asking the question but I figure the only stupid question is the one not asked.

-Corey

 

[2deuce]

The bigger tires will lower that 4.56 ratio as opposed to the stock tires but when you raise the truck to make them fit your mileage suffers. That being said the more fender trimming you do to keep the truck lower the better the mileage should be. I have the 38" tires but haven't decided to put them on my M1009 or the M1008. Too many decisions.

 

[2deuce]

The thing that will affect your mileage more than anything else is the kind of driving you do. I drive my M1009 to work every day but I only go 4 miles and don't go over 35mph. If I drove the M1008 I think my mileage would be similar. If you do alot of freeway driving and don't need the hauling capability of the M1008 get a M1009. Even with the M1009 you will look for more speed and lower rpms on the freeway but if you raise the truck much to fit the tires, don't expect an increase in MPG. These vehicles are not aerodynamic at all anyway and it gets worse the more it goes up.

 

[Wyofj40]

Maybe another dumb question. How does lifting a vehicle decrease fuel mileage? Its the same vehicle, you're not adding any additional mass or wind resistance. The only way I can see a decrease in mileage is the larger tires will throw your odometer off displaying a lower number of miles than what was actually driven. But I may be missing something.

 

[Hartinarmz]

Yes these are all things to consider. I do not need the lower gearing and towing capabilities of the M1008 but would just rather prefer it. IDK if I should try and sway my mind to the M1009 or not though. I drive a brick already so I am familiar with these lovely aerodynamics . MPG is just one of the many things I am considering. If I really cared about it I would ride a bicycle.

 

[dskchevy]

If I keep it around 65-70 I get 20-22 mpg with a M1009 with 31-10.50...................

 

[2deuce]

When you raise your truck it adds wind resistance. One of the ways the new car manufacturers increase MPG is limit the air flowing under the vehicle. Air drags going under more than going over or around so the higher you get the more air you push. Plus the faster you go the more energy it takes to move through the air. Below 50 mph it isn't the issue with mpg, but over 60mph aerodynamics starts becoming much more important. My M1009 can get 20mpg but I have to keep it under 60mph and run close to sea level. The turbo definitely will help with mpg especially at higher elevations. I want to say efficiency drops 2% every 1000' of elevation, but it may be more and a turbo would take care of that loss. Add a turbo if you have one.

 

[Cryogen]

In theory it should help your highway mileage but it never works like that.

Coming from the Cumminsforum where you can run 38's stock w/o a lift they bring your mileage down a lot. I suppose in theory if you were on the highway but still they do raise your truck a few inches and thats what kills you, as well as stopping and starting now became quite a bit harder for your motor.

If you like MPG the best are small HARD tires...

 

[48cj2a]

I can't see where raising a brick in the wind is going to hurt your gas mileage. These are not exactly aero dynamic to begin with. Your driving habits will effect the mileage more.

I've had several GM trucks with 33" all the way up to 40" tires. Pick an all terrain tread 10.50 -12.50 and not a big cleated mud tire. Keep your foot out of the pedal and you will be fine. A 4" lift will not clear 38s with the square front fender wells without a whole lot of trimming. Best you will do is 33 - 35s and may still need a little trimming if you are in the 35-36" tires.

I had a 3" body lift and 7" of spring lift on a Blazer to clear 40's and still had to trim the rear edges of the front fenders a bit. Put u-joints in the rear about once a month (young and dumb at the time)

 

[Hartinarmz]

Yeah driving habit seems to be the main killer. Probably just going to keep stock ride hieght and stuff the biggest all terrain under it that I can. Thank you for the help gentlemen.

 

[burbn10]

I got 37's and a 4" lift on my M1008. Absolute minimum fender trimming. (less than 1/4") I average about 16mpg on the highway at 55mph. That Sidewinder setup will help the MPG's too. Don't expect to travel fast in a M1008 though.... Even with 37's my upper limit is about 65mph... And that is with the engine screaming like a banshee.

 

[AJMBLAZER]

11.00R16 Michelin XL's on stock GM steelies. 38x11's basically. Fit under the fenders, 1" of front lift, cutting, and some hammer use on the wheel tubs up front. Fit fine but I am going to push the front axle forward an inch.

Last I knew I was getting around 13mpg using very rough math. Might be a BIT better, but not much. I saw around 15mpg when I had the 36" HMMWV bias plies on.

Doesn't help my 38's are Load Range E meant to be under a LAV-25. Something like 4300lb load rating. They're heavy, 130lbs or so...run smooth as silk though.

 

[Davepo99]

I have been researching alot and just wanted to clarify as to this theory I have been hearing. Do bigger tires in fact raise the highway mileage of an M1008? I am wondering because the vehicle I purchase will be a DD and I am debating between the M1009 or an M1008 with minimal lift and 38's. I would also be putting the sidewinder kit on either vehicle that I get. Sorry for asking the question but I figure the only stupid question is the one not asked.

-Corey

i dont think air resistance has anything to do with it
i think bigger tires would help gas milage
difference is weight of larger tires vs stock smaller tires

 

[Bigferg1993]

@AJMBLAZER
In my personal oppinion, that is how a truck should look. You still have the stock springs on it correct, if so how well does it flex in offroad situations? Thank you in advance.

 

[jmro]

I just bought a m1008 and I am kinda wondering how high and what size tire I want to go with. I had been doing quite a bit of research and I am thinking I may try to run 11.00x20NDT (43" tall) or the smaller one that is like a 9.00x20NDT(40" tall). The reason I am looking at these tires is that they are taller but they are not super heavy or wide. Sharecropper did a build with the 11.00x20, those tires look mean on the m1008. To gain mpg we need a taller, thinner, lighter tire vs oh say another military tire that weighs 150lbs per tire.

 

[jesusgatos]

Just bought an M1031 and have a set of 37" HMMWV wheels/tires that I was planning to throw on it. Been searching for info about fuel economy and haven't found much, which seems kinda weird because I know it's a pretty popular combo. 15-ish?

 

[truck1]

I get 17-20 mph in my 1028 with Gear Vendor IF I stay at 65 or less. 4 " lift with surplus 37" radials on old Chevy 16.5 " rims. Nice catch on that 1031 from Herlong by the way.I salivated over that rig and almost out bid you!

 

[AJMBLAZER]

I got about 15 with the bias ply Humvee 36s.

When I put the 38 inch Michelin XL's on it dropped to about 13. The taller tires made the engine rev less however they were a lot heavier.

 

[jesusgatos]

I get 17-20 mph in my 1028 with Gear Vendor IF I stay at 65 or less. 4 " lift with surplus 37" radials on old Chevy 16.5 " rims. Nice catch on that 1031 from Herlong by the way.I salivated over that rig and almost out bid you!

How's that OD setup? Have an SM465 and a D18 transfercase with a .25% Warn OD that I could throw in there, but a 5spd or OD auto would be a lot nicer. But you know how much I paid for that thing, and there's not a lotta cash left over to spend on parts right now.

 

[truck1]

I like the GV setup. Easy install, just need to shorten your rear drive shaft, and since I lifted 4" with new springs and shackle flip 7/8" shims were needed between the crossmember and frame to drop the drive line angle. That's about it. 2 years now with 0 problems and 65 -70 mph @ 2310 Rpm's. The install took about 4 hours. But they are pricey- 2800$ new from a GV dealer in Texas drop shipped direct. I like the TH400 with the 6.2. But if you have the SM465 setup, that might be cheaper. Anyway I kept it simple and it works fine for runs from Marin to Mendocino to the country and freedom! Again nice score on the 1031. If I won it I was going to leave it all stock and use it as a portable maintainence truck for my property. Add a welder and tools and you could do just about anything mobile.