Just brought a new Chev Silvarado 1500 with 20" Goodyear Eagle tires. When doing a little research on the tires, which I wish I had done before buying the truck, found out they're passenger car tires....
Who cares - at least you'll look good with "chrome 20s" when you cruise throught the drive in on Sat night with your TT. Actually I have towed thousands of miles with the same tires, seem to be as good as any I've used. I do add a couple extra pounds to the rear tires.