Your rear limit is more spring and tire/rim ratings than the axel. IIRC the axles in most of the trucks these days are in the 11-12000 lb relm. The 7500-8000 lbs relm on yours is the springs and tires.
If you have not done the airbags, a redone spring set would be my choice. From using trucks commercially over the last 40 plus years, I've found spring additions to be best.
On one of my GM SW rigs, I took the 5-1 spring pack, made it a 6-1 with slightly thicker leaves, went from 6400 lbs to 8500 lb rating. It handled loads the same as my later model dually with an 8500 lbs spring rating. If you do not have an above the main spring pack overload, this may be all you need to do to keep the truck level, especially if it is a higher capacity one, ie a 1500-2500 lbs option.
Taller to slightly wider tires would also help. You may/probably will need wider rims. My current 1500 had 8.5" rims, I was able to go from 265-65 tires to a 285-65 and not have too narrow of rim issues. Vs some previous trucks coming with 6.5" rims, going from a 245 to a 265 gave me handling issues vs 7.5" rims and 265 tires. Wider will be a better option here vs taller. Taller will make you effective gear ratio's taller/lower. If you have say 3.73 axle gears now, a 275-70 toa 295-70 will lower this to around a 3.55. A 4.10 to a 3.95. A 315 will knock these down to a 3.42 or 3.73. SOME vehicles this is an issue, others its not so much. You also may start getting into clearance issue with the tires while turning, of bouncing on rough roads, speed bumps etc.
Enjoy the new combo.
Marty
