The front wheels also have 10 holes- - - -the reinforcing plate just covers up half of them since there's only 5 lugs on the front hubs. Your photo doesn't show enough detail, but it appears you've got a 3-piece wheel with a small locking ring holding a full-circle bead ring in place on the front wheel. The bead ring and lock will be facing inward on the rear wheel where it can't be seen without unbolting the wheel. Any commercial truck tire shop should be able to service those wheels, as long as they're not rust-damaged enough that they don't lock together safely. They don't appear to be widowmakers.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!