It could be a number of things and maybe several together.
I didn't see if you mentioned what gears you have but 3.92's with 1st gear on the 8 speed is a significantly steeper ratio than your old truck had with the 4.56's. Big difference.
Add on to that the 35" tires and you are really making it worse yet - the laws of leverage will not be denied - there is a reason people use a pipe or breaker bar on the end of a ratchet! Which is what 35" tires are to the brakes.
Throw in cold ceramic pads and they could all add up to your issue - especially if your engine rpms are higher than 500-700 rpms - IMPORTANT.
But
You could also have an issue with the brake system.
I would try stock pads with new or machined and properly bedded rotors and if you can possibly do it, borrow a set of stock 20" wheels and 33" tires and see what happens. (Basically a stock truck)
IF it still does it after that then you would have to almost conclude that it is a braking issue - master cylinder, proportioning valve, air in lines, stuck caliper, etc.