So you spend over $50k for a shiny new F-450 and over $40k for a big ole fiver to pull behind it and your really concerned about a couple mpg? Sorry don't make sense to me at all. Drive a small car or hybrid and stay in a motel it will be a lot cheaper.
To increase the 2011 Super Duty F-450ís top end speed, they have added new tires which designers say raises the Super Duty F-450ís top speed above 90 mph.
I didn't realize top speed was such an issue. I don't know why you'd want to go over 80mph with a heavy trailer anyway. Tires can easily withstand short term use over there speed rating anyway. I'd rather have the 19.5 12 ply tires.