ib516 wrote:
It's not just rotor size that determines brake capability.
It's the overall mass of the rotor for better heat load - heavier can absorb more heat - these are friction brakes after all. It's also determined by the calipers. Number of pistons, the hydraulic pressure used to actuate them, etc. There's also different materials used for the friction pads, with different coefficient's of friction in the material.
I think this is fluff answer...of course that all matters. But assuming that the main truck manufacture's don't have their heads up their a**. Then we can assume that the heavy 1/2 tons offered have huge disc brakes with big calipers and 4 pistons per.
If that's the case then there is nothing that says a 3/4 ton will stop a load better than a 1/2 ton.
Change my mind.