Originally Posted by rockcutter
Thanks for input Kevin. What about load range C- LT/tires? They are rated l860 lbs. @ 50 air pressure. I think the airstream weighs 5600.
I am with Craig on the ST vs. LT - - my Overlander had LT tires on it when I purchased it in 1995, and that was among my very first changes. The ST tires are designed for use on trailers and LT tires are designed for use on light trucks - - the stresses involved are different; and the ST tires also have additional UV protection that you can't get with LT tires.
There are several considerations to be made when choosing between C and D load ranges. First of all, the general recommendation has been that a coach that has been run with C load range tires should not be upgraded to D load range as there is the potential for structural damage to the wheel. (This is one of the reasons that I chose to purchase new wheels for the Overlander with its first set of tires since the history of the wheels on the coach was an unknown.) The second consideration is whether the C load range actually has sufficient capacity for a particular coach. The empty weight of your '76 Ambassador is likely at least 4,900 pounds and could be more depending upon the options installed - - the loaded weight is generally at least 1,200 to 1,500 pounds greater (remembering that the empty weight does not include the significant weight added by water, and LP; as well as the weight of options and accessories; and the weight of supplies and clothing. My '64 Overlander has an empty weight of 4,440 pounds, but has a loaded gross weight of between 6,000 and 6,100 pounds. I have been running Good Year Marathon ST tires in the 227 75 R 15 Load Range D on my Overlander since 1995.
Good luck with your tire decision!