8.25" Alcoa wheels shouldn't exceed 120 psi
Looks like wheel size is the key. I noticed that the Michelin Tire Guide footnotes are very specific as to the maximum tire pressure allowable on the 8.25" wide wheels (120 psi) vs. the 9.00" wide wheels (130 psi maximum).What this means is that I could only run 120 psi on my 8.25" wide wheels if I run the larger size 315/80R 22.5 tires and thus would only get a maximum of 8,000 lbs on the wheels while the 12/R 22.5 tires size on the same 8.25" wide wheel at maximum psi of 120 gets 7,390 lbs.
The larger 315/80R 22.5 tires are significantly more expensive then the 12/R 22.5 tires. When I priced out the tires locally, including balancing, installation and all the various taxes they ran about $535 for the 12R's and $769 for the 315/80R 22.5 for the Hankook AH11/12. So it would cost me around $235 more per tire to gain only about 610 pounds more per tire--not a very good value equation in my eyes. Now if my 8.25" wheels would have allowed for 130 psi, which they won't, I would have been able to get a full 9,090 lbs per wheel and I could see the value of using the more expensive tires. But I'm not willing to risk running my Alcoa 8.25" wheels higher then the factory recommended maximum of 120 psi.
Nope, I'm sticking with the factory recommended 12/R 22.5 tires all around on my rig.