Just wondering...

I don't go off-road. I drive it on the street, haul big or heavy stuff in the bed the car can't handle and tow.

My Tundra is a TRD with a Sport Package. For argument sake, lets just say a Tundra TRD Sport with the 4 WD and Tundra TRD PRO have the same tires. How much more "off road" can the Pro handle? BTW My Bridgestone Duelers suck. Which is why I said "same tires".

 

I don't have a Pro or a Sport, so take this with a grain of salt, but there are some differences in suspension that would matter. The Pro suspension is tuned for offroad, so it's going to ride better on it, and I am pretty sure the Sport has sway bars that are going to limit wheel travel. Tires are primarily going to affect your traction, where as the suspension differences will affect clearance in unique situations, flex, and shock absorption. Equal traction isn't going to be equal performance on varied terrain.

 

^^^^^
Like azure said, the suspension is the only difference. They power train and traction control are the same.

 

Assuming you put 18" wheels on your TRD Sport with the same tires as the PRO, you'd be limited by front ground clearance, suspension performance, articulation (your sport has a rear sway bar and a stiffer front bar, the PRO has no rear sway and a softer front bar), protection (the PRO has a larger and stronger front skid plate as well as a crappy plastic skid plate on the gas tank which may or may not do anything in an offroad application.
Those are about the only notable differences contributing to off-road prowess. For the sake of argument though (tires being the same), your TRD Sport is damn close performance-wise.