We went from stock 245s to 265s, they are just over an inch taller and less than an inch wider, did not see much of a difference in towing prowess with our 4.10 gearing.
All we noticed at first was they were a bit squirrely being that the new tires had a more aggressive tread design, and were constructed with stiffer sidewalls and harder rubber compounds for their extended mileage rating.
About a mile difference on the speedometer in town and 2mph at highway speeds. Since we tend to do most of our RVing off the beaten track we really appreciate these tires as opposed to the stock LT highway tires.