Just bought a 2017 Thor Vegas. It has the 2016 Ford e350 chassis with 225/75R16E tires. I want to buy a spare rim and tire but am having a hard time getting the proper spec on the rim (steel rims not aluminum) Apparently the rim on the e350 chassis changed around 09 so the older ones are not compatable. Dont know if that is true or not. Any e350 experts out there to shed some wisdom on this???