Duel, duelly, duellie, duelie: none anywhere close to correct.
"Duel" is a conflict or combat, such as dueling with pistols at 40 paces.
The correct term for paired wheels/tires is "dual." Thus, a truck with paired rear wheels/tires would be referred to as a dually or duallie, depending on the manufacturer's choice as both are slang words.
"Duel" is not correct.