Well, despite what has been posted here, I've learned a lot after owning my 2010 Platinum over a year now.

A taller tire provides more sidewall between the rim and the road. Towing capacity of the truck, and load range of the tire has little correlation to impact protection. Swapping the 20 inch wheels/55 series tires for 18 inch wheels/65 series tires improved the ride quality of the truck in all conditions, towing or not. The sidewall rating is the same on both tires. Though I've only been towing race cars and travel trailers for over 20 years, I've apparently missed the wisdom of several guys here. Yet several guys on here know what they are talking about year after year.