Michelin did previously list the 9" wheel only for the 315 XZA1 tire. Like John stated Prevost ran as standard a 9" Aluminum wheel with a 8.25" steel inside dual. The original concern was not for "pinching" Michelin was concerned with "dual kissing" where the 2 tires would contact at the lower bulge, and cause excess heating of the carcass. With the advent of the 315 XZA2 Energy tire Michelin took another look at the 8.25" wheel, and has approved the 8.25" wheel for the 315 XZA1 & XZA2 tires. I had spoken to Michelin's engineering people about 2 years ago, as I have chrome plated 8.25" Aluminum Alcoa's, and wanted to run the 315 XZA2 Energy tires. I did not want the cost of new wheels & the plating of the 9" wheels (the plating was $500/wheel 9 years ago) You can run the 315's on the 8.25" wheels without any problem. If the 8.25" wheel has a non-standard offset. You may still want to make sure you have adequate spacing on the dual application.
Steve & Rhonda Bennett
Dana Point, CA
92 Marathon XL40
2012 Jeep Rubicon Unlimited
Owner: California Coach Company, LLC