Not a problem since I don't have a real truck.
Not true, different size tires on an axle with a clutch type limited slip will wear the clutches out very quickly.
Context: "What would be the downside to having to run a smaller tire in an emergency for a short distance" - none
To be fair you did say to run it all you want.
Indeed. Unless you're running a 5-tire rotation the spare is just a spare. Use it as such, for emergencies and short distances. Some people say run it on the front except I have serious concerns with different diameter tires on the front when it comes to braking. Some minor wear on an LSD to get home when you're talking about a 5% difference in OD, not so much.
Did this once, 7 miles to the my exit got a flat, I live less then a mile off the exit. Crap running slicks 28 inches tall only have a stock size spare (around 26 inches), can't swap front to rear running skinnies on the front. What to do? Well I put the spare on. Less then 8 miles killed a Ford 8.8 Trac Lok that worked perfect before. Now granted that was a 2 inch size difference but goes to show it doesn't take much. Point is have a proper size spare.
My Mustang.
True, but most of those vehicles also have an open differential, so it's kind of irrelevant. Not that I care to check but I would venture a guess that most vehicles equipped with a limited slip diff (at least a clutch type) are equipped with a spare that is less then a few percent different in height then the factory equipped tires. I rebuilt that rear and when I pulled it apart the clutches were trashed. I know it worked earlier that night because I was at the track and had done multiple burnouts.
So those burnouts didn't cause the wear, it was the smaller tire....I get it now lol.
