I just switched out the P245/70R17s on my Durango for the same size in LT LR-E. I needed new tires, anyway. I'm happy with the result while towing my new 21DK. Unless very heavily loaded, the Suburban would have to perform as well, if not better.
I inflated the tires according a pressure chart found here
. With only 3700# on the rear axle fully loaded and weighed on a scale, the specs indicate that I should have 40# in the rear tires. (It lists only LTX A/T for 245/70, not M/S, but where both M/S and A/T tires are available in the same size, the pressures are the same.)
40# is lower than I expected. I'm guessing that 45 or 50 may firm up the ride while towing. I'm not concerned with disproportionate wear, for the little towing I do relative to when I'm not.