1999 2500 cummins 245 75 16 this is my stock size looking for something a little bigger to fill wheel well up and look nice not to big mostly highway driving around town etc.

 

305/70R16 bfg at, will fit on a stock height truck with stock wheels

 

If you keep it stock height I would say a 285/75. If you level it I would say a 315/75

 

305 is the same height just 3/4" wider

 

Good year duratracs are better than the BF Goodrich AT, Michlins are the best milage, not the best traction. I had a buddy who runs Dick Cepeck A/T and got 60K out if them on his 94 Cummins reqular cab.

 

i am having good luck with hancooks.

 

US tires are made of a different compound.
Much harder than european.
There is no other way to reach the manufacturers tire mileage warranty.

BFG's are known in europe to last forever, but they are known to develop no grip during rain.
Michelin's are known to have an outstanding grip during rain and on dry roads over here- but they extremly expensive.

To get a overall information about the tire have a look at this:

Uniform Tire Quality Grade (UTQG) Standards:
http://www.tirerack.com/tires/tirete....jsp?techid=48