A "split rim" wheel has one removable bead ring and must use a tube-type tire with a heavy rubber liner between the tube and the rim. Tubeless tires won't seal on a split wheel, regardless of the bead ring design. Someone has retrofitted your truck with aftermarket single-piece wheels suitable for tubeless tires. What size (rim diameter) tires are you running? Probably 16" or larger. If the rim size on the sidewall is a "XX.5" size such as 16.5, 17.5, etc., that's a special tapered-bead tire that requires a wheel that matches the bead shape of the tire. Regular full-inch bead diameter tubeless tires WILL NOT fit on .5" rims- - - -it's deadly dangerous to try to make that combination work.
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!