[65comet]

I've had off-size spares before. If I had a flat on the drive axle, I'd put the spare on the other axle then use the correct sized tire from that other axle to put on the drive axle. Highway speeds with different size tires puts a lot of strain on the differential to have the two axles going at different speeds. It takes extra time to do the two changes, but I feel it is worth it. Especially in an older vehicle where you don't know how the additional strain may affect the drive line components.