I'm running 205/70's(26.3" dia.) on knockoffs. For a spare I have a 195/75(26.5" dia.) on a original 5.5" steel wheel. Your 215/70's are 26.9 " dia. The original 6.70's were 27.1" dia. I installed the 10.25" long front bolts and installed two .5" thick washers between the frame and the rear lock bolt bracket so the lid would close with the wider spare tire. One thing to consider, if you have a flat on the front, you will need to have someone to help you to hold the brakes while you remove the knockoff wheel adapter if you use a steel wheel for a spare. If you do use a steel wheel other then an original one, make sure the pilot hole in the wheel is large enough to fit your front hubs. I'm not sure when they changed, but newer wheels have smaller pilot holes. My 205/70's will fit (when flat) into the tub and your 215/70's should also, when flat.