After Market Rims

There are almost as many brands of rims out there as there are species of fish in the ocean. Really you need to know how much weight the rim can support. Also, look at the off-set of the rim. Many websites will recommend rims for your truck, but they have different offsets. The RAM's natural offset is something like +45 or +40. Very far off-set to the surface of the rim. Most aftermarket rims will have +20, 0 or even a negative offset for that deep-dish look. Try to get something between +20 to +40 to maintain your offset, otherwise you will have a lot of tread sticking out from your wheel wells and kicking up dirt and sand on your paint (unless you invest in some fender flares and mud flaps). You can also introduce abnormal wear on your bearings as a rim of vastly different offset will place a different load on your unit bearings.

Lastly, make sure it's the same bolt pattern as your ram. I honestly don't remember what it is but a little google-fu will help you find it.