Your tires capacity can limit your max load, but having excess tire load limit capacity will not improve your payload beyond that. Running hard compounds will improve your fuel consumption, utility score and lower maintenance costs, but if you can get a soft sports tire big enough for your load, it will still work just fine.
Ride height, spring rate, type of suspension chosen (eg solid leaf carries more than double wishbone), type of spring chosen (progressive carries more than standard, active more again, air even more, and hydro is king) will all play a part of the payload number.
Towing limit is currently a little bit broken\untuned as of yet, but it factors in a towing speed, so having a lot of torque available at the wheels (read low gears as much or more than big engines) is the primary factor, but higher vehicle weight, excess brake capacity ect all help.
Utility and commercial vehicle buyers will also want high cooling factors (the fuel efficiency cost of which can be offset if you have active cooling flaps. but the cost\complexity makes it not universally worth it) and generally 2 seats. They aren’t moving a family, but a race style single won’t do either.