I have a '03 2500 with the 5.7 motor. I run the stock size tires which is a 265. I was thinking of changing the gears in my truck to a higher number. It has 3.73's now but was thinking 4.56's. Is this a smart move? Im just trying to get rid of the truck always down shifting on the freeway so much. It's always doing it even empty with a head wind.

 

Its weird but a "higher number" means really a lower gear. Thats just FYI.

But there are online calcs that let you see what rpm you would be running when you enter things like tire size, gear ratio, ect. That might help you out

 

I know a couple of guys who have the factory option 4.10s and love them, even with larger tires. That said, if I was gonna spend the $$$ I'd go straight to 4.56s. With your tranny, you aren't going to lose any appreciable mileage on the highway over the 4.10s and will see a performance benefit as well as having the tranny work less...