M35A3 wheel o-rings, what number

[tobyS]

I've read a lot of threads about o-rings and that the M35A3 and larger cousin the 939 combat wheel use the same o-ring. I got some of the 1/4" ones with MRAP steel wheels, which appear to be about 18.5" ID before they are stretched on. I planned on using the NOS ones I have until I saw small cracks starting. I've got one tire o-ring and valve stem being changed tomorrow that I'll have to check, as I found 8 of 10 are bad so far.

Here is a statement from the last line of one thread;

"The m35a3 O-rings are about .170 in dia., regular truck O-rings are about .250 dia. Using the fatter O-rings in a3 rims has stopped any leaks in this area for me."

Okay, so please help me here. I see some vendors offering the 3/16" o-ring for the M35A3 wheel, which contradicts using the 1/4" one mentioned.

Also the o-rings I have seem to have to be stretched, starting about 18" ID.

Thus I'm searching for the optimum A3 wheel o-ring and how I should expect it to fit on the rim. Should it be an 18" inside, 18.5", 19", 19.5" or 20".

So far, I'm leaning to a 1/4 cross section and starting at 19" ID so there is some stretch to stay in place. That would be a - 467 in McMaster Carr.

Please keep me from making a mistake if I am choosing the wrong o-ring. Thanks for your help.

Edit; what buna number? I see on one site the 90 durometer is cheaper than the 70.

 

[simp5782]

Does your's have any numbers on it? If so or you want to start in the basement and see what you can figure out contact Stacey at TechServ@gemplers.com Tell him what the application is for and he should be able to find it. I remember getting some for an A3 awhile back but I can't find the receipt on what the number was.\

On another note everything I have seen for surplus sites on their O rings they say the A3 and the 5 tons are the same so I am sure they are mentioning the OR220TG it is the 1/4" size. The LMTVs use a 19" x 3/8" I think and its an OR420A part number.