tnt3616, I am sorry that I do not have the answer to your question but I do welcome you to iRV2.com. We are glad to have you join us here and look forward to reading your posts. Have you tried contacting Firestone? Sometimes they know what the manufacturer used in production. You will probably have to contact the home office tech support team. Good luck and keep us posted.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7