Help Needed..How to calibrate for NITTO 305's

I took my truck into the dealership to have them adjust the computer to calibrate for my larger then stock tires. They couldnt find my tires on the list. they were looking for 305's../ daa i told them that they are compareable to 33". still wouldnt do it because there isnt an exact code for NITTO 305's
I know they must have it because if you by a lifted truck from the dealership specificly the ones in my area they all have the NITTO 305's on them.

Does any one know what tire size is on their programmer list that would be comparable to the NITTO 305's?

Any help is greatly appreciated.

Thanx