So, are you looking to upgrade to 19.5s or keep the light duty 17/18/20s? You didn't say.
You also don't state what rims you currently have. If base model 17s, finding tires with high load ratings is now next to impossible.
18s and 20s, there are a plethora of tires int he 3400 to 4000lb load cap range, just pick one.
Most aftermarket 17/18/20 wheels are rate around 3500lbs per tire. Method NVs are rated 4500 iirc.
Finding OE rim load ratings is difficult, but one can reasonably assume they're at least rated in the 3500lb + range based on some models weight and available payload.
My recommendation for strength, other than going to 19.5s, is OE 18s or 20s alloy wheels with some stout tires.
Been packing 7500lbs plus on the back of SRW trucks with OE wheels for a long time without issue. My rationale is there is NO WAY that a truck mfg would not put a substantial factor of safety on HD pickup wheels. The risk would far outweigh the small financial gain of cheaper wheels.