I don't see where there would be a problem with the size overall, but there might be 2 issues. I'm under the impression you're running a wider rim, say about 7"? That would ok for the 245. Now here's the real problem, the Long Trails are too low of a load rating for that truck. If i recall correctly, that size only comes in a P rating, about the same as 4 ply in a bias. You're going to need at least a D rating, about 8 ply. I bet those tires came off of a Tahoe/Suburban/Yukon, right? That's an oe tire on them.
BTW-I'm running a 30x9.50x15 on mine, roughly the same width and diameter as a 245/75/16. No rubbing problems at all.
