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CCKW Wheel Tips

Dr. Deuce gives us tips on how to deal with CCKW/Chevy Wheels. Posted 1/26/2005

 

In my experience owning CCKW’s for over 24 years, the wheel problem has been the worst and most persistent problem with these WW2 GM military vehicles.  

There are a number of wheels that will ‘fit’ on a CCKW including M35 wheels. Even considering just wheels that are made for 7.50 x 20 tires, there are a number of different designs that will ‘fit’.  

Wheel Basics

Back then, there were no such things as tubeless truck tires like there are now. Back then, all the wheels had to come apart in one way or another to allow for the mounting and dismounting of the tires.  

bulletThe easiest ones to dispense with are the so-called Combat Rims. These are like the rims on the DUKW where the wheel is comprised of two dish-like pieces that are bolted together with the tire captivated in between. These wheels have the advantage of allowing the tire to be changed with wrenches and sockets in the field by unbolting the two sides of the rime from each other. They have a disadvantage after 60 years of being difficult to get the tire away from the wheel because they usually have a large flat area behind the tire that can get rusty and prevent the rim from sliding over. If the rim happens to have a run-flat insert installed, after 60 years get out the Sawzall for the tire…..
bulletAnother type is a standard split rim design comprised of two pieces, the wheel and the lock ring. If you have seen an M37 wheel apart, this is that type. With this wheel, the locking ring actually goes under the bead of the tire which prevents it from spreading and unlocking. This is probably the safest ‘split rim’ other than the combat rims.
bulletA different type used by Chevrolet back then has three pieces: the wheel, the removable ring and the small square split lock ring. With this type, the removable ring is prevented from coming off by the split locking ring. To remove the split lock, the removable ring must be pressed towards the other side of the rim to relieve the pressure on the lock ring. Outward pressure exerted by the tire just keeps the lock ring in place.
bulletThen there is the ‘come apart in the middle’ rims. You can tell these because the wheel itself will have a raised area about ½” by 2 ½ “right in the middle of the rim. Sometimes you can see this area when the wheel is mounted as an inside dual and most definitely when it is the outside dual. These are very dangerous and most tire places will not touch them.
bulletFinally there is the CCKW rim. This is a somewhat unique design that features a wheel and lock ring. The lock ring however is ‘stretched’ over the wheel to mount it or dismount it. To help this ‘stretching’, a couple reduced locking areas are made into the lock ring. They are not that difficult to ‘stretch’ after you have learned the tricks and done a few. No part of the lock ring goes under the bead which means that the tire is trying to push the ring off at all times.

With any truck wheel and tire, if you do not know what you are doing or do not have the proper tools and safety equipment, TAKE THEM TO A PROFESSIONAL! Two (or more) piece truck rims play for keeps! Most of the ‘old wives tales’ you have heard about these wheels are NOT ‘old wives tales’. I personally know of a local young man (at the time) who nearly bled to death after a ring hit him in the jaw removing most of his teeth and shattering his jaw….!

I have changed all but the come apart in the middle types and have done about 40 CCKW wheels myself.  I also now have an older Bear truck tire changing machine that will do 16 to 24 inch truck tires. When you have over 150 truck tires…..  

The tire machine will remove a tire in any condition from a standard CCKW wheel. If it on there with great amounts of rust from years of being mounted and the tire is decrepit too, the Bear Tire Machine will literally take the tire apart!  

I take very specific precautions when re-inflating a tire after being mounted. You cannot bee too cautious with these wheels especially after 60 years. Of course the mating areas (locking areas) of the wheel and ring should not be too rusty or pitted. In my experience, I have never had one too rusty to be considered unsafe by me unless it was rotted out as explained below. A good idea that I use it to take a prick punch and put a number of punch marks on the ring next to the pry slot and an equal number of punches on the flat surface by the lug holes. This way you can ensure that you reassemble the correct ring with the correct wheel especially if you are cleaning and changing a bunch of wheels at the same time. Try to save and use your best wheels with un-deformed or bent rings on the front of the truck. Remember that the tire is trying to push the ring off at all times and that on the front the ring faces out towards people….  

The biggest problem in my experience has been the wheels rotting out. Yes, I said rotting out, not just rusting. The way these wheels and many others of the day were constructed is that you had the wheel rim and the wheel hub that has the lug nut holes. The fingers on the hub were bent over and riveted to the wheel rim. What happens is that moisture get between the fingers and the rim. Over time, the moisture eats away at both the rim and the fingers. If you look closely, you may notice wheels where the fingers have started to bulge upwards. These wheels are on their deathbed and should be deflated and cut with a torch to render them un-useable. Worse yet, sometimes the rotting attacks the rim more than the fingers. This is really dangerous.  

I had a friend with 42 Chevrolet civilian truck (same wheel construction) who was driving along the interstate at about 45 miles per hour when he experienced a catastrophic wheel failure due to the rim rotting out under a finger. All of a sudden there was a loud bang and as he stated; “I didn’t think I could stop the truck before I lost every nut and bolt in it…’ The lock ring did not come off and the tire did not lose air pressure. What happened is that the rim got about ¾ inch wider in one place! What that did was make a giant flat spot in the tire that was not really noticeable. The truck sure noticed! He nursed the truck home and looked at it for hours before figuring out what had happened. My friend was lucky that the ring did not come off or that he did not lose air pressure. The tire was on the front!  

Many people also do not use the correct lug nuts on the front. I have done it too, used the inner dual male-female nut sometimes with the outside dual nut on it. We have all seen the single wheel special nuts that are made for the front, but how many of use them all the time on the front? Recently, I had a wobble on the front of my Bomb Truck. I assumed that the older wheel-tire combination might have been a little bent. It was bent, but bent because three of the six male-female nuts had pulled or broken through the wheel! I had never seen this happen before in over 20 years with these trucks!  

Copyright © 2005 Stephen Keith

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Site opened 1/7/2005 Last modified: 03/12/2013 17:52