tire weights via email from BFG...
In regard to weights, we can provide the following information:

All Terrain 31x10.50r15 weighs 41.28 lbs
33x10.50r15 weighs 51.00 lbs

Mud Terrain 31x10.50r15 weighs 44.03 lbs
33x10.50r15 weighs 47.30 lbs

If you have additional questions, please respond to this email
or you may call us at 1-877-788-8899 (toll-free) between
8:30AM and 6:00PM Eastern Time Monday through Friday to allow
one of our Consumer Relations Representatives to assist you.

BFGoodrich Tires
Consumer Relations Department