Let's Talk Combat Rims

[w30bob]

Hi Guys,

I'm a bit intrigued by "combat rims". I guess my first question is why were they called that? They sure seem to make it simple to change a tire....just undo the bolts, break the bead, and off comes the tire....right? Why were they replaced by the Budd wheels we all have on our M's.....were the combat rims too expensive? Were they really better, meaning more stout, than the Budd wheels?

thanks,
bob

[52 M-42]

I don't know a lot about combat rims, just a little. They are a WW II artifact. It was supposed to let the driver / assist driver fix flats. It is really a bolt on bead retainer not a true split rim. I like "the look" and convinced myself that I could change and repair my own flats. I can too, except for airing them up. Never had the guts to do that. I always take them to the tire store and have them put them in a cage. I'm just a frightened little girl I guess, but I'm alive with all the pieces still attached.

The Budd rims with the spring retaining ring is is supposed to be even easier (if you do it right - that "right" seems to be the problem). The spring ring is much easier to become a disaster and support services became much better as time went by. We still had both types when I was in the Army back in '68 to '71. Maintenance fixed flats by then so we didn't care; we just had to change tires.

All my tires, truck & trailer, spares, extras, etc are all on combat rims. I even have a couple of extra rims. I have one complete set of spring rings because those are "correct" for my truck & trailer but they are naked. No tires, tubes or flaps.

That's all I got.

52 M-42

[Carter]

Combat wheels were part of a run flat system that allowed a tire to stay on a rim after it was punctured and had gone flat. The rim had an internal bead lock that held the tire on the rim and allowed the vehicle to continue to be driven during a combat emergency to get out of danger. A family friend Col. Ray W. WWII vet and automotive engineer told me that in testing at APG of trucks and Jeeps equipped with them when run on a test track the tread portion of the tire had separated from the sidewalls the vehicles speed increased since it was only running on the sidewalls that were held in place by the bead lock.

[k8icu]

I believe Carter's explination is correct. They were part of the runflat system in place back then. I believe the cost for a combat rim was more expensive than the split ring budd rims and that is why the army changed to them. Funny how we've gone full circle. HMMWV, FMTVs and so on all use a split rim/bead lock rim with a run flat insert to allow the truck to continue driving even on flat tire. Leasons learned are lost and relearned again I suppose.

[w30bob]

Hmmmmm........remember when I was asking what the purpose of the 12 tire clips (6 per side) were on my M's wheels......as we learned they were in fact there to act as a rimlock (bead lock actually). I wonder if the Army thought the lower cost Budd with the 12 bead lock clips was a cheaper replacement for the combat rims....but also retained some of their run-flat feature? Interesting stuff.

Thanks guys,
bob

[ZGjethro]

Hmmm, my truck tires have no clips on them. I bought the truck three years ago from a fire dept with brand new Snow King tires on it. The tires are held on by the lock ring and nothing else. Is this correct and safe?

[w30bob]

Hi ZG,

Yes, it absolutely is safe. I believe (but can't prove) that the clips I'm referring to were found to be not needed to keep the tire bead from breaking from the rim at low pressures. As far as funtionality in a run-flat situation.....I don't know. Seems those clips were discontinued pretty early in the M37's history....so don't worry a bit about not having them. And if I'm sounding a bit like an "expert" here I assure you I am not. If I'm wrong about any of this someone please jump in and kick me in my butt.

thanks,
bob