air bag load rating????

im looking for bags for the back of my dually. they must be able to support the weight of a 3 car wedge fully loaded with the heaviest on top would be a mid size suv. i have a semi parts dealer from me and im looking at some double bellows. i cant find a load rating on the net for them. can someone help me out please.

they are goodyear part number is 2b12-406

thanks in advance.

josh