>>28472500
Different size tires have different diameters, so at any given vehicle speed, the two tire sizes will be spinning at different speeds. The differentials are there to make up for this to some extent, but only really for turning (and when all of your tires are the same diameter). If you have different size tires, the differentials are working overtime to make up for the difference in speed constantly, even while you're going straight. This puts more friction and thus more heat into them, wearing them out faster. Tires are cheaper than transmission rebuilds.
https://youtu.be/yYAw79386WI