Because one side of the car/truck/van weighs more than the other end. If you don't rotate the tires the side that has more weight will wear much faster than the others, and will have to be replaced more often than the other tires. It's best to just rotate them so they will need to be replaced @ the same time.
Your front tires wear more quickly than the back ones because of all the turning left and right that they do over time. The back tires are in a fixed straight line so they always wear slower. That plus the fact that most cars are front-wheel-drive these days. But the same holds true even for rear-wheel-drive vehicles, the differences in wear rates are just a little less dramatic.
5 months ago
Last edited at 8:34AM on 11/30/2013
basically because of the front ex: steering linkage tie rods ball joints struts ect ect in time what is known as toe in effect this affects the tread of the tires so to keep tread wear more even rotate tires if you ever notice one tire wearing quicker than others check under car components if in front tie rods or ball joints or struts usually are the buggers that cause it in the rear depends on car or truck from leaf springs to struts to shocks ect ect..in some cases a simple alignment maybe needed for front.
They wear evenly when you rotate them. Especially if the front wheels are out of alignment. This can cause cupping or gouging. In small cases it's no big deal because you can rotate the tires and even out the unusual wear pattern.