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  #1  
Old 09-29-2004, 08:27 AM
stevewhitter stevewhitter is offline
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New tires on a car, front or back wheels?

While flirting with a car-crazed female friend, we got into an argument about the placement of the newest tires on a car. Should they be installed on the back wheels or on the front wheels. I contradicted her assertion because I remembered reading that the local car columnist said so… I couldn't explain why I disagreed with her and when I decided to google for the answer, I realized that every “expert” has his own opinion and very little explanation to back it up and even less proof.

Does the answer depend on the climate or if you are attempting to improve a specific aspect of the car’s handling. Back wheels for traction and front wheels for braking?

Steve
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  #2  
Old 09-29-2004, 08:37 AM
Kimstu Kimstu is offline
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The Car Talk guys have spoken on this subject:
Quote:
Dear Tom and Ray:
My tire dealer, Quasimoto, looked askance at me with his one large eyeball when I told him that you guys had told a caller on your radio show to put the two new tires on the back of his pickup truck. Now, I don't want to get my tire guy upset, because he is an expert, after all. But when he finally swung down off the ledge, he acted pretty steamed, since he had just installed two new tires on the front of my Toyota Corolla. Does your theory apply only to pickups? Please clarify this for me. -- Leslie

Tom: Well, it's not our theory, Leslie. It's the tire industry's theory. Or, more likely, the tire industry's lawyers' theory.

Ray: For some years now, tire manufacturers have been recommending that installers put the newest tires on the rear wheels of all vehicles. Why? Well, the theory is that you have steering control over the front wheels, so if the front end loses traction, you're more able to maintain control of the car. Whereas if the rear end loses traction, you might quickly find yourself in deep doo-doo (i.e., skidding out of control), and you'd have a harder time recovering.

Tom: My guess is that this policy came into being when a customer, or his or her heirs, sued over this very issue. So, from then on, the official recommendation from tire manufacturers was to put the newest tires on the rear.

Ray: Now, don't be too hard on poor Quasimoto. We were just recently enlightened about this ourselves. And if you go to 10 tire dealers, seven of them probably haven't heard of it, either (even though they'll embrace it when they realize that it can be used to encourage people to buy four new tires instead of just two).

Tom: In any case, we do agree with this policy. And not just because our lawyers strongly recommend that we agree with this policy. So ask Quasimoto to move your new tires to the back, Leslie.
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  #3  
Old 09-29-2004, 08:37 AM
El_Kabong El_Kabong is offline
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IANA mechanic, but if the old tires were rotated according to recommendations, all four tires should be more or less equally worn and all four should be replaced.

If it's a front-wheel drive vehicle, and if one insists on only buying two tires, they should go on the front, as the bulk of traction and cornering loads are concentrated there. The rears pretty much just hold up the back end of the car.

If it's a rear- or four-wheel drive vehicle, IMO you are compromising safety to some extent no matter which end you put the tires on.
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  #4  
Old 09-29-2004, 08:38 AM
Xerxes Xerxes is offline
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I'd think it matters whether the car is FWD or RWD. I drive a Miata (rwd) and from personal experience new tyres on the back can give you more traction (power on the road) and will curtail oversteer (back-end stepping out), but given that a) the steering's done from the front and b) when you brake hard you're loading the front end, if I could only afford 2 new shoes, they're going on the front.
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  #5  
Old 09-29-2004, 08:41 AM
stpauler stpauler is offline
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Michelin suggests sticking them on the rear:

Quote:
When only two tires are being replaced, Michelin recommends that the new tires go on the rear, whether your car is front-wheel, rear-wheel, all-wheel or four-wheel drive.

"The new tires will grip the road more effectively and evacuate standing water more efficiently than the worn tires," said Ron Margadonna, technical marketing manager with Michelin.
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  #6  
Old 09-29-2004, 08:47 AM
Gary T Gary T is offline
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Ideally, the tread depth difference between front and back is minimal, and is kept that way through regular tire rotation. Then all four tires are replaced as a set, having worn out more or less equally. In the real world, this doesn't always happen, of course.

For safety reasons, it is generally recommended to put the tires with significantly more tread on the rear. This is to minimize the chance of the rear tires losing grip on a turn, which is harder for most people to deal with than having the front tires lose their grip. And this works just fine with rear-wheel-drive vehicles. The tread on driving wheels tend to wear at a faster rate than the front ones. Eventually the rear treads will wear enough to allow normal rotation to be resumed. It obviously makes sense to put new tires on the rear of a rear-wheel-drive vehicle.

On front-wheel-drive cars, it's a different situation. The front tire treads will wear faster, even more so than on rear-wheel-drive cars, because they are on both the driving wheels and the steering wheels. If you put new tires on the back, the tread depth difference gets exacerbated. This is its own safety issue, as vehicle suspensions are designed under the assumption that there is essentially equal tread wear front and rear.

So now we get into the area of opinion. On a front-wheel-drive vehicle, one can argue there's a problem putting them on the front, and one can argue there's a problem putting them on the rear. In my opinion, it makes more sense to put new ones on the front, because eventually normal wear procedures will lessen the problem. Some shops, however, give more weight to other concerns, and will refuse to put the new ones on the front. I don't believe there is a definitive, unarguable answer to this one.
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  #7  
Old 09-29-2004, 08:47 AM
Xerxes Xerxes is offline
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Quote:
Why? Well, the theory is that you have steering control over the front wheels, so if the front end loses traction, you're more able to maintain control of the car. Whereas if the rear end loses traction, you might quickly find yourself in deep doo-doo (i.e., skidding out of control), and you'd have a harder time recovering.
Yeah, but if you've got two balding tyres on the front, you've seriously compromised your steering control (and, assuming we're talking safety here) in a 'situation' I want some steering and braking.

Also, unless you're driving like an F1 driver, or unless you're really not paying attention, you'll feel the back end begin to let go. Lift the gas and it should stop the stepping out.

Actually, thinking more about it the height of the centre-of-gravity of the car could play a role here. In my car (very low CoG) I've deliberately overdriven it so the back end stepped out, so that I could learn what it feels like - it's certainly the case that lifting off the gas quickly brings the back under control; I can imagine it might be different if you're driving a stonking huge SUV.

On preview I see that Michelin recommends new boots on the back. Oh well, guess you've gotta go with the manufacturers......
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  #8  
Old 09-29-2004, 10:40 AM
Dag Otto Dag Otto is offline
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Quote:
Originally Posted by Gary T
For safety reasons, it is generally recommended to put the tires with significantly more tread on the rear. This is to minimize the chance of the rear tires losing grip on a turn, which is harder for most people to deal with than having the front tires lose their grip.

That makes sense for wet pavement. On dry pavement, does tread depth affect traction at all? In my experience, it doesn't.
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  #9  
Old 09-29-2004, 12:53 PM
AllShookDown AllShookDown is online now
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Quote:
Originally Posted by El_Kabong
IANA mechanic, but if the old tires were rotated according to recommendations, all four tires should be more or less equally worn and all four should be replaced.
Last week or the week before Tom & Ray said in their newspaper column that getting your tires rotated was pretty much a waste of money. Money spent on rotation vs. money spent on getting new tires sooner made it a wash.

Anyway, I'm surprised to read all this about new tires going on the rear. Every time I've been in the situation of replacing only two tires I was told they should go on the front because it was more important to be able to stop.
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  #10  
Old 09-29-2004, 01:59 PM
danceswithcats danceswithcats is offline
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While I understand what you're saying Gary T, it makes more sense IMHO to have the best sneakers up front, since that is the steering axle, and also because I live in an area where we have rainy days. I would think that the deeper sipes on new skins would reduce the likelihood of hydroplaning at highway speeds. Also, the majority of braking is done by the front wheels on my truck-I replace pads on the front 3x before a new set of rear shoes is required, and no, the proportioning valve isn't adjustable, from what I've learned. That's why I've always put the best rubber up front.
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  #11  
Old 09-29-2004, 02:19 PM
brad_d brad_d is offline
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I was (for some reason) under the impression that the new-tires-on-rear theory dealt primarily with braking.

If your rear tires lose traction and lock up under braking, it doesn't matter how much grip you've got in the front - you're going to have a swapping-ends problem. Whether the vehicle is front-, rear-, or all-wheel drive doesn't really affect this.

How this is impacted by the presence of rear- or four-wheel ABS I couldn't say.
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  #12  
Old 09-29-2004, 10:06 PM
Telemark Telemark is offline
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Quote:
Originally Posted by brad_d
If your rear tires lose traction and lock up under braking, it doesn't matter how much grip you've got in the front - you're going to have a swapping-ends problem.
That's the reason I've always heard. If your rear wheels lock up, they will have less braking, and will try to swap ends.
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  #13  
Old 09-29-2004, 10:10 PM
danceswithcats danceswithcats is offline
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At the risk of sounding like a wise guy-if you know how to drive, you won't lock the brakes, and therefore it becomes a non-problem.
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  #14  
Old 09-30-2004, 03:16 AM
snailboy snailboy is offline
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If you're driving in the rain, it's certainly better to have your front hydroplane than the rear. If the front hydroplanes, you'll lose most braking and steering. Basically you'll be stuck going in a straight line at the same speed. That typically doesn't cause an accident. If the rear end hydroplanes, I give it at most a second before it slides out from behind you assuming you're going straight. Once that happens, prepare for a wild ride.
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  #15  
Old 09-30-2004, 02:04 PM
stevewhitter stevewhitter is offline
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follow up

I'm glad that my question got people talking and I must admit that most of the arguments for one choice versus another do, for the most part, seem to be logical and well thought out. That's the whole problem isn't it? There must be ONE answer if we're talking braking and steering.

So far, in the absence of any responses from experts who've studied the issue, I have to lean towards the back tires because the manufacturers apparently recommend it. The only reason i lean that way is because of the huge liability they would have if they were wrong. I'm assuming they invested some money in actual studies.

I know I'm making big assumptions, but in the absence of any evidence to the contrary, i'd put the two tires on the rear of the car.
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