whats everyones opinion on having 2 diff. sets of tires on at the same time

[blueb8llz]

yea thats what i was thinking. why not try two of the top favorite tires at the same time right....but someone said its a bad idea because if the two tires are different in diameter or if one is softer in rubber ..etc. will hurt the diffs.
what u guys think about what hes saying?
i really want to try running two different sets, but if this will cause some trouble either with the diffs or anything, i rather not do it..