Just going off what I can see in the picture, those tires look a hell of a lot like Toyo Open Country M/T (I have them on my Excursion, great tires, BTW). I'm guessing about a 37" 13.5x 22. Going off the toyo website, they are load range E with a max load of 3420 per tire. Yeah, I think it will be O.K.
My Exy has an 8" lift on 37's. The lift iteself really don't hurt the pulling, but the overall lower gear ratio does. To get in the sweet spot of the motor (about 1900) rpm means I'm going nearly 80 mph (on the GPS). I really need to drop the 3.73 gears down to a 4.11 or even 4.56, but I just have been too cheap so far.
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