Ok...I know not to run different size tires, especially in 4wd, but I now find myself needing to use a spare that's a different size. I lost one of my front 235/75/15's today and just realized the spare I have is a 225/75/15. I'm 60 miles from the nearest tire shop. I'm thinking it would be best to swap one from the back and use the spare on the rear so my front tires are the same size and not bind up the front driveline. Am I thinking right in that it would be better to put the smaller spare on the rear where there is some slip in the differential?

 

With open diffs front and rear I wouldn't think it mattered where you run it. You should be fine anyway, the difference in size is small.

 

very minor difference

 

You should do any harm with that small of a difference as long as you keep her in 2wd like you mentioned.