Take a look at the Sizes & Specs chart on this page and see the 15" size wheels. The 5 lug wheels are rated 2160 lbs and the 6 lug wheels are rated 2860 lbs. These are the same wheel, just with a different number of lug holes. That is what is referenced on the back of the wheel, same casting but with 5 or 6 lug holes.
https://www.tredittire.com/wheel/altitude/