While shopping for new tires, I came across a local tire place’s web site, an article on which insisted that, if you only purchase 2 new tires, they should be on the rear wheels. That sound counter-intuitive to me, as the front wheels do all the steering, and most of the braking. Are they right?
In a low-traction situation, if the front wheels have lots of grip (new tires, deep tread) and the rear wheels have much less grip (no tread, hydroplaning or whatever), then the rear-end will swing around (oversteer). People are very bad at dealing with that situation. If the reverse is true, the car will just slide forward (understeer). Both situations are bad, but the industry has figured out that understeer is predictably bad, especially since the front of the car has crumple zones and airbags and all that. If you oversteer, you’re more likely to do something dumb with the steering wheel and end up sideways into a tree.
This is why all new cars sold today are set up to understeer, and why tire places want to install new tires in the back.
Overall, the drive wheels tend to wear tread faster than the non-drive wheels. In front wheel drive (FWD) vehicles, where the drive wheels are also the steering wheels, the difference in wear rate is greater than in rear wheel drive (RWD) vehicles where the non-drive wheels do the steering. Typically a FWD vehicle will need tire rotation by about 6,000 miles, whereas 10,000 miles is the norm for RWD vehicles.
On a RWD vehicle, it makes sense to put the tires with the most tread on the rear. This works both for the reasons steronz has explained, and for the purpose of evening out the wear, over time, between the front tires and the rear tires.
On FWD vehicles, these two factors are at odds with each other. In the course of normal tire rotation schedules, the front tires wear down more than the rears, then the tires are rotated (with less tread now on the rear), then after time the more-tread tires that have been put on the front wear to become the less-tread tires, then they’re rotated again, repeat every 6,000 miles. Ideally, all four tires become worn out at about the same time, and are replaced as a set of four. But in the real world, often two need replacement while the other two still have a fair amount of life left. So do the new tires go on the front, where the wear will eventually even out but the chance for a rear wheel skid is increased, or on the rear, where the wear difference – already greater than in a “normal” rotation scenario – will become greater yet?
From my observation of this issue, I’d say that the main reason tire shops insist on putting the new ones on the rear is fear of lawsuits. If the two old tires have a reasonable amount of tread, and the vehicle is driven with reasonable care, a rear wheel skid is not particularly likely. But this being America, a certain percentage of people can be expected to drive a bit too vigorously, get into a rear wheel skid, and then blame (and sue) the tire shop for the resulting damage. It’s a lot easier to put the new tires on the rear than to get everybody to drive with proper caution.
The funny thing is, most of those shops will rotate tires that have that much wear difference between front and rear. They just won’t install new ones that way.
To follow up on this. If your car oversteers, the back end comes around. If the back end continues to slide you will spin (best case) or roll the car. If the rear tires catch some traction, you will suddenly accelerate perpendicular to the road. Think of walls, fences, houses, pedestrians etc. in your front windshield. I saw this happen once and the car ate a lightpost.
A car that understeers will not spin and unless in a really tight turn, the car subtends a small angle to the road.
Another vote for the best tires on the back. I run my new car until the fronts are worn out, move the backs to the front and buy 2 new tires for the back. When the front are worn out, repeat.
Thank you thelabdude this seems like a good workable plan, I may try it 
My personal experience, based on about 5-6 vehicles over about 20+ years, is that the front wheels wear out faster regardless of whether the car is front or rear wheel drive. Signficantly faster, for the most part. Possibly my alignments have sometimes been out of whack, but that has not generally been the case, and I don’t think that accounts for it.
I appreciate that you’re an expert, and I don’t mean to dispute you, but this has been my experience.
I tend to just replace all 4 tires at the same time and rotate them throughout their life.
Significantly faster on FWD vehicles is definitely what I’ve observed. On RWD vehicles, the difference I’ve seen in tread depth is less, even at 10K miles, than on FWD at 6K miles, but I recall it being more wear in the rear. I don’t know the reason for the difference in our experience. One possibility might be if you do lots of city driving with lots of turns. 
This is the ideal. Engineers design steering and suspension systems under the assumption that all four tires have essentially equal wear. Regular rotation to effect this helps maintain the desired balance of traction between front and rear.
Just another reason rear wheel drive makes more sense, except for the added cost, complexity, inefficiency, and reduced traction. But those things are nothing compared to rear-end rocking, rubber burning, tire screeching peel outs.
For some of the cars, yes.
Come to think of it, the car for which it’s most pronounced is a Ford E-150, which is RWD but mostly driven in the city. This has had the front tires replaced twice, but the rear tires have never needed to be replaced, in over 60K miles. So maybe the main determinant is city versus Hwy driving.
But it’s also been true of my other cars, some of which have been driven mostly on highways.
I always thought the main reasons were the turning, as you mention, but also the fact that the main weight of the engine etc. is on the front wheels versus the back. It would make sense to me if added weight would create more wear on the tires.