can putting on the wrong belts mess anything up?

[budgetown/6]

i recently changed my ac, power steering belt and fan belt. i bought some duralast belts. the new belts were definitely different than what was on there before. i figured the old ones were wrong because they were super lose. the new ones seemed to be thicker and a tiny bit smaller but they fit fine (i think). Anyways the length of the new belts seems fine but im not sure about the thickness? they went on and seemed to be right but my engine seems to be running a little louder. im kind of a hypochondriac so it might be nothing. thanks so much for any help.

[monty23psk]

Different size belts can be ok as long as there is no rubbing and the proper tension is there. Also if the belt doesnt still right in the pulley, you can get the belts to slip. So you might get a different sound from the belts due to the size difference.

[HATER-PROOF]

When you say that your belt's are "a tiny bit smaller" are you speaking of where the belt fits inside the pulley?  Because If you are, then yes your engine will sound strange, because what going is the belt's that you've put in-place are not wide enough to keep a grasp for the job that they need to perform.  Imagine it this way-you're holding on to a pull-up bar with grease on your hands(new thin belt's).  Basically your pulley from your A/C is trying to work to capacity, but doesn't have the grip that's needed from the belt to rotate properly.