Small tire size on dually's

[Mark_Z]

Why is it that GM uses smaller size tires on their dually's compared to Ford and Dodge? GM uses LT 215/85R16's. Is there a benefit to this size of tire vs. a larger size? Tell me your opinions.

[Heartbeat Hauler]

I believe that tire size is used to fine tune the rpm range for the truck, and the 215/85/16 allows for optimum performance (in GM's eyes)for the drive train.
P.S. I think they suck and GM should offer a 4.10 rear gear option with taller tires i.e. 235 or 255/85/16's. That's my opinion. :D
JP