Originally Posted by SandCastle
Originally Posted by BeerCan
Costco will not rotate tires that have a tread difference between front and rear tires is more than 2/32nds of an inch. This is policy at sam's club as well. It is because if they move tires with less tread onto drive wheels, it is considered a safety issue. They have been sued in the past for it after people get in accidents, so don't blame Costco, blame the lawyers who go after deep pockets.
A few years ago when replacing a rear tire (destroyed by a pothole) on my FWD car, I asked to put the new tire on the front. But Discount Tire insisted on putting it on the rear to minimize the risk of losing control due to oversteer. This might be a legitimate concern on the race track, but for commuting at legal speeds what's the risk? Besides, either way they are vulnerable to an unscrupulous lawsuit, because it could be argued that the driver could have stopped faster and steered straighter had the new tire been put on the front and the accident avoided.
If you read the article on tirerack, it basically says that the reason they're on the back is that on a curve, the rear will spin out if there's less tread on the rear. If the worn tires are on the front, the front will give out first, but it's easier to control. Once the rear starts sliding out, very few people are good at recovering from it and you end up in a spin.