Ok, so the gf’s car needs 4 new tires, but she can only afford 2 right now. We go to our local Costco and they tell us that it’s their policy to mount all newer tires on the rear of the car. The Costco worker tells us that a recent study, done by Michelin, proves that control comes from the rear tires. He then tells us that most people dont believe it, but it is true.
Of course, after we leave, I tell my gf i am one of those people.
I could maybe see it in a rear wheel drive car, but in a front wheel drive car? I tried doing a google search, but came up empty.
He also said it was due to become a federal law soon; that is, requiring all tire outlets to mount the newer tires on the rear.
Does anyone have any knowledge of this, or links to cites on the web?
Actually, I was just in the Sears Auto Center for something completely unrelated to tires and I saw a sign stating that all major tire manufacturers now recommend placing new tires on the rear of all vehicles. I thought it was strange, but didn’t pay much attention.
They should also mention that when the rear end swings out, it’s called oversteer. Pretty easy to remember, since the car turns far more sharply than you had asked for.
On the other hand, *understeer * is when you turn the wheel, but the front tires aren’t grippy enough, and the car tends to plow straight ahead.
As you might imagine, an oversteering car can get out of control pretty easily, especially for a non-expert driver who doesn’t know how to deal with it. The rear end can swing all the way around past the front of the car, and now you’re in a spin-out.
But if your car understeers, usually if you can slow down some, the front tires will regain some grip, and you can bring the car back under control.
Also, it should be noted that many drving enthusiasts enjoy some oversteer once in a while. If you know how to control the car, it can be a lot of fun when driving in a safe area.
I assume they also recommend against rotation of the tires once the new ones are put at the rear? On most front wheel drive vehicles the front tires wear much faster than the rears, so the mismatched tread depth isn’t going to get better - it’ll get worse.
For that matter, even rotating tires (on a FWD car) that are all the same age will likely mean moving the more worn tires from the front to the rear. Does “the industry” have any unified comments on this?
As far as I know there is no recomondation against rotation of tires by any car maker, or any tire maker.
The difference, in handling of a set of tires with several thousand miles on them vs two brand new tires, and two almost worn out tires is dramatic. Unexpected oversteer will cause most drivers to get a brain vapor lock.
Example 4 tires mounted with 12/32" of tread. 7,500 miles later fronts have 10/32" rears have 11/32. Rotation evens out the wear, and the difference is not noticable.
Compare that to mounting two new tires 12/32 on the front, and the two old tires with 4/32 on the rear. 7,500 miles later the fronts have 11/32 and the rears 3/32. (1/32" above worn out) Hit a puddle in a corner and kiss the ass of your car goodbye.
The recomdation for new on the rear, is not new. When I sold tires for Montgomery Ward back in 1971 this is what the tire industry council suggested.
Well, it must be new for Discount Tire. I don’t recall when I bought my two new tires, but I’ve only had my car for five months, and I didn’t buy the tires immediately. But when I did buy them, I asked the service technician to put the two new ones on the front and take the best two of the original four and put them on the back. They did without blinking.
Rick, please help me out, becuase I don’t see where you actually answered brad_d’s question. So, the only tire rotation I should do, unless I choose to replace all four tires, is simply left to right?
It makes no sense to me to put the newer, more grippy tires away from your most important wheels… the front ones. Isn’t braking the most important thing you do in a car and isn’t most of the weight of the car on the front tires while braking? Unless you own a RWD car and have a habit of ripping around every turn with decent throttle, you want those tires on the front. I’d love to hear the reasoning behind this law…
I just read the link. Makes sense in theory… put the treads where you can’t control by steering. But, if it were my car, I would still want to be able to brake as well as physically possible, rather than avoid a rear-end swinging around when I can just go slower on the wet road and avoid that consciously with common sense. I worry about unexpected and sudden braking performance more than myself going too fast around a turn in the rain.
Also, stopping in the rain requires the front tires to channel gallons and gallons of water away, something that new tires can do a lot better than old ones. I worry about being able to stop quickly in the rain… losing my rear-end around a turn is an afterthought compared to this.
On a new car, or a car running four tires that were bought as a set, you should rotate your tires as recommended. The exact pattern will depend on the car type (FWD or RWD) and the tire type (directional or not).
If you’re running two new tires and two old tires it’s a bit trickier. I can’t really find anything on this specific instance. I guess I’d just rotate them left to right and try to save up for a set of four. This Goodyear press release discusses buying tires in sets of four versus two.
The steering and suspension systems of cars are designed with the assumption that there will be roughly equal grip on all four wheels. This is most readily achieved by having all four tires of like type and similar amount of treadwear. Rotating tires is recommended and beneficial in maintaining equal treadwear over the long term. Then it’s a simple matter of replacing all four as a set when they’re worn out.
Some people neglect tire rotation, or choose to replace them two at a time rather than four at a time (which doesn’t save much money in the long run, but does present a smaller replacement bill at the time). Then they have two worn out tires and two that could be used for many more thousands of miles. It seems to make economic sense to just replace the two worn ones. The problem with this approach is that it can lead to consistently having significant treadwear discrepancy between the front and rear tires, meaning the car seldom has the desired balance of grip.
On a rear-drive vehicle, putting the two new ones on the rear makes sense, as it helps prevent the rear end from breaking loose and over time the treadwear front to rear approaches evenness. On a front-drive vehicle, it’s a dilemma. New tires on the rear can be safer, but the treadwear discrepancy will increase. New tires on the front could, over time, even out the treadwear, but the car is potentially treacherous in certain situations.
I would lean towards recommendations from tire experts, tire manufacturers, and vehicle manufacturers for where to put two new tires. But I strongly recommend avoiding getting into this no-good-solution situation by replacing tires four at a time, and rotating them throughout their lifetime, so as to always have fairly equal treadwear. How much money is your life worth?