[Elwenil]

There are very special preceedures you MUST follow when mounting tires on split rims. If you screw up and inflate a tire that isn't seated properly on the split ring, it can fly off with enough force to literally cut you in half. A commercial tire shop can change them for you if they have a cage or some guys that know how to do it without the cage. You basically have to be very careful when dismounting the tire and ring, so you do not bend the rim or ring, or damage it's seating surface. When inflating the tire, you must put it inside a cage for this purpose, or wrap chains through the rim holes and around the tire and bolt them together good so that it will retain the ring if it should come off. It's also a very good itde to use a 10' air line with a gauge, so you can stand back away from it, and lay in face down on the ground when inflating. These rims can easily kill you if you don't know what you are doing. It is possible to change them yourself, but you must know the proper proceedures and be very careful. I HIGHLY recommend you find a shop to do them if you have never done it before.

 

[Elwenil]

Those rims in the pic are standard military split ring rims, so all of the things in my above post applies. They can be very dangerous if the mounting is not done properly. Take it to a professional. The money it would cost you is not worth you or someone else's life. There was a guy near here that had one come apart on him, around 1995. It just grazed him, but it slit his neck to the bone. He bled to death before anyone could even get to the phone to call 911.

Here is a page on safety when dealing with split rims. It's from down under, but the info still applies:
http://www.safetyline.wa.gov.au/pagebin/pg000677.htm