I just got my truck back this afternoon with my 6" Skyjacker suspension lift and new wheels and tires. I can definitely tell that I need to change gears. I am geared right now at 3.55 and now have315/70/17 BFG All Terrains. I wasoriginally thinking about getting 4.56 but I wanted to get some opinions. I hardly go off road and I would like to keep my highway mileage up and RPM's down as much as possible while still getting a good jump off the line. I am thinking now about getting 4.10.

I will post up some pictures of the truck as soon as it stops raining this weekend.

 

245/75/16 to 315/70/17 has lowered your final ratio from 3.55 to 3.15.
With 4.10 gears the final will be 3.66. Probably be performance nuetral or just slightly slower than before because your spinning a lot more wt farther from the axles now even though the final will be slightly better.
With 4.56 gears the final ratio will be 4.04.

IMHO the 4.56 would be the way to go. Shouldnt see any real mpg loss unless your really diggin the trq increase and getting into the gas more than prior to lifting it.

Now lets see those pics

 

I am not really concerned with the MPG's right now, after I just put in my Magnaflow and Mopar PCM, Icant seem to not have my foot in it all the time. But it would be nice in the long run to get decent MPG's as well as performance gains. Thanks for those number conversions, that will really help in my final decision.

 

456 all the way