5 ton sprag & tires

[Castle Bravo]

I have a M818 5 ton tractor that I'd like to put some Goodyear G286 tires on the front axle while keeping the stock 1100x20 NDCCs on the rear axles. These tires are new, and I suspect (I can check) that they are greater in diameter than the stock and somewhat worn down 1100x20 NDCCs.

Is it okay to do this, or will the difference in tire diameter cause problems given that the truck has a sprag?

I suspect that the amount of "slop" before the sprag engages power to the front axle (7%?) can account for some difference in tire diameter. I have consulted the TM and searched the forums, but I have found no clear answer.

 

[OPCOM]

It's tricky with even that much difference. For sure you can end up with the drivetrain bound up even going down the road. You might not notice it, and it's not like it will leave any rubber marks, but the wear on the drivetrain will take its toll eventually. Someone here sells a kit to put the 5T transfer selectively in "front axle disengage" mode, and that seems lie s good option for your application.

 

[papercu]

Goodyear G286

Isn't that a 24" tire and a Radial? Wayne

 

[Greeniron2010]

if i am correct a 14.5/20 tire is same height at 1100 but just wider. Will be like a floater tire on front of a dump. Id love to get my hands on a couple 14.5 but i only need the tires and all the ones for sale are rim/tire combo

 

[gringeltaube]

The catalogs show the G286 also in 11.00R20 and I think that's the case here...(???)

Now what really should be compared is rolling radius or better rolling circumference with tires mounted at correct TP under (normal) load, front vs. rears. Not just O.D. according to catalogs or even measuring tire diameters still unmounted....!
Let's assume the new GY's really are relatively large for its nominal size and somewhere close to 21" (which I doubt!) - measured from hub center to floor, while the bald rears only measured 20". That's a 5% difference or less; road contact would still make the fronts turn faster than if they got powered from the TC so wind-up simply won't occur.
Now if we put 395/85R20s or 15.5s up front but kept the old 11.00-20 NDCC for the rears it probably would be over the limit: 22"/20" = 10% dif.! Via the now engaged sprag the rears would try to turn the fronts faster than the road passing underneath! Not so good...

G.

 

[papercu]

http://www.steelsoldiers.com/deuce-modification-hot-rodding/12312-goodyear-g177-g286.html I don't see mixing radials and belted tires. Wayne

 

[jasonjc]

I run 12.50R20XL with 9.00X20's on my deuce's, but they have the air shift. I've seen the military run the highway typ tires on the front and NDT's on the back of 5 ton's.

As for me I see a lot better truning and handling on my truck's

 

[papercu]

I wonder how DOT or the insurance would see it? Wayne

 

[gringeltaube]

Don't know about the DOT regulations there but it shouldn't be a problem as long as you don't mix radials and bias on the same axle.
Technically it's not. Actually it can help improve handling and safety when running radials on the steer axle and keeping the bias on the rear tandem.

G.

 

[Castle Bravo]

Isn't that a 24" tire and a Radial? Wayne

Its a radial 1100R20.

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I have thought about disconnecting the front driveshaft or perhaps disconnecting the air to the sprag.

 

[timothy1]

Not to dig up a old thread but looking to do the same thing mentioned. Anyone figure out if its ok to run a radial tire on front and keep rear ndt? Or even put a wider tire on front to act like a floater tire on front? My truck I got fronts are shot and like idea of a radial vs bias. And I have 1100s on truck stock

 

[73m819]

as long as the dia. is the same or a bit more then the rears, you will have no problem, the sprag does care about width just the dia.

 

[Castle Bravo]

I have had the aforementioned 11R20 radials on the front axle for about 18 months and about 1500 miles with no apparent ill effects. I know of other trucks with this same setup with no apparent ill effects either.

 

[timothy1]

Thanks for the feedback. Been possibly looking for some like 14.5 tires to put on it, but seems I read a lot of issues about using the hemtt rims or stock. So I will look for 2 radials and put on front.