The 15x7" Cop wheels are Heavy Duty, that's the reason they were part of the Police Pkg. They are heavier than the std 15x7" steel Mopar wheel. I don't know about the 15x8" Super Coupe wheels, I doubt they are HD.

The heaviest axles that use the 4.5" on 5 bolt pattern hub are refered to as 3500lb axles. They are refered to as that, but the mfgs rate them with a 2990lb max load, so all you need is a wheel with a load capacity of 1500lb min, even the std steel wheel should handle that.

The next axle size up is the 5200lb and uses a 6 bolt lug hub.

FWIW, I use 14x5.5" Rallyes on my trailer.