Only Replace Front Tisres; Potential Problems ?

Same size, no problem.

I have no opinion on the Michelin Harmony in particular, but Michelin generally does make a decent tire. Expensive, but good.

the OEM tires are Goodyear Integrity? Replace all four. $99/four specials from Pep Boys are better than those execrable pieces of shit. I've had two company cars with those tires OEM and they're unbelievably awful. Little traction in dry, *NONE* in wet.

You probably ought to have the alignment checked; I "inherited" my current company car at 17K miles and it was well out of alignment. (Chevy Impala; not the exact same car but they are both FWD GM products...) I had to have it aligned again after that, and it currently only has about 48K miles on it. Another problem you'll likely have is constantly warped brake rotors... (other than those two items, and a few ergonomic quibbles, I actually think the new Impala is relatively OK however.)

nate

I wouldnt replace them with Goodyear.

And I dont know about Michelin Harmony , but I CAN tell you that all Michelins are NOT high quality.

You didnt get much mileage out of those original tires.

Go to

Many tires will give you superior mileage, excellent adhesion, and quieetness, but YOU MUST RESEARCH them to find the best.

You should, of course, check alignment, etc, before putting on new tires. But still, 14K miles sucks elephant wangs for mileage.

Michelin made the Kirkland brand tires for Costco. These tires were so good (not) that Costco discontinued them.

The current thinking seems to be that when only 2 tires are replaced, put the grippier ones on the back, especially on FWD cars. This way, the back end will not be as likely to break away. I have been told this by several tire dealers.

"warped" is a common misdescription of the real problem - poor seating. try scraping off the hubs and the inside of the wheel, smearing a little antiseize on the contact points [being careful not to get any on the disk], then torquing the wheel bolts by hand in a two torque stage process.

every time i take my hondas to the shop for tires or the like where the shop has the wheels off, they come back with terrible "warping". with the procedure above, the "warping" completely disappears. every time. if the disks were truly warped, that would not be possible.

they're right in that. think about it - if you're cornering, the rear always takes a tighter line than the front. tighter line rear at the same speed as the wider line front means more cornering force on the rear, thus there must be more force for the rear to break away - and unless there's mud on the road, that's what we find in practice. it's more recoverable with rwd, but with fwd, that can be a problem.

moral of the story: best tires on the rear.

That is apparently correct.

The real reason for that advice has to do with cornering/braking stability. Most drivers tend to be able to recover from understeer (front loses traction first) than from oversteer (rear loses traction first) because the intuitive reaction (lift off the gas) is the correct method to recover from understeer, but the exact opposite - keep your foot in it, and maybe accelerate lightly - is the correct way to recover from oversteer, which is non-intuitive.

When braking, if the rears break traction first, suddenly the braking force on the rear wheels decrease as the rear wheels are now in sliding friction rather than static (rolling) friction which results in less force. Thus in effect you are trying to balance a pencil on its point, and the rear end of the car will try to become the front.

But in the case of the OP I would just replace all four tires and be done with it because I've never driven on a worse tire than those Goodyear Ingetrity ever in my life.

nate

It's a company car; unfortunately it gets serviced at one of two "approved" shops. So I have no control over how the hubs are cleaned or the lugs are torqued unless I want to redo their work every service. (rotation interval is something like 7500 miles - seriously. I guess GM is admitting that their front suspension geometry is garbage?)

I did have to have the rotors turned at about 20K miles. They really were warped (or whatever) so badly that the whole car would shake violently whenever braking Both fronts and rears. They did the fronts but that didn't solve the problem, I had to take it back and after they cut the rears it was OK again. At the time I blamed it on abuse by the previous driver(s) but they are bad again less than 30K later, not as badly, but getting there.

nate

well, there's no way /i'd/ drive a car with that problem - i'd just take the wheels off, do the scrape and anti-seize thing, and put the wheels back on as described, company vehicle or not. this is a personal safety thing, not a "but it's not my car" thing. and you don't have the excuse of not having the tools.

of course!!! the only time it gets solved is when the hub gets cleaned up as part of the work. and because nobody seems to know or bother to think this through - it's only ever solved accidentally, and at excessive expense.

once the corrosion sets in, of course!

but anyone that's driven rwd knows this nate - it's why race cars are rwd.

again, the "balance the pencil on its point" thing works with rwd, not fwd. see above. for fwd, which has many advantages in most driving situations, recoverability from a rear wheel slide is not easy because you can't push the pencil tip, only drag the eraser.

If we're talking about braking, it doesn't matter if the car is FWD, RWD, AWD, 4WD, whatever - if the fronts lock first the car will simply keep going in a straight line from the point where the wheels locked up. (as you say, dragging the eraser.) If the rears lock first and the driver doesn't immediately let off the brakes, it takes a combination of luck (that is, the car is traveling dead straight on a perfectly flat road) and reflexes to keep the car from trying to swap ends.

I had a graphic demonstration of that on the highway one morning years ago... found out that the load-sensing prop valve was frozen on my old GTI 16V the hard way. Was tooling along at about 70 MPH-ish when I was cut off by another driver (who changed lanes only a few feet in front of me, obviously not checking her mirrors) and so I braked hard. Next thing I knew the back of the car came around - felt like about 45 degrees but I'm sure it was less otherwise I wouldn't have been able to recover from it. A definite pucker-string moment for sure. And that was a straight, flat, dry road.

I ordered a new prop valve that same day.

The point is, the same effect can occur if everything is mechanically working as intended but you have rear tires with significantly less traction than the fronts. Heat-cycling tends to make the rubber of a tire harder and less grippy, so even dry weather traction slowly decreases as tires age, so the advice to put the newest tires on the rear makes sense for *any* vehicle, FWD or RWD. (on an AWD or 4WD vehicle the tires should always be replaced in sets of four.)

nate

we're not talking about braking, or at least, not braking in a straight line. if that were so, life would be easy. we're talking about being able to corner, and not have the rear overtake the front of the car.

like you, i have experienced this exact same problem, so i know this scenario. but that is a braking fault, not a lateral traction issue.

not entirely true. heat can indeed make tires harder, and they lose their ability to displace water as the tread wears, but, most quality manufacturers these days use multiple compounds in the tire tread. including grippier compounds to keep the tire safer as you get nearer the wear limit for precisely this reason.

indeed. as a function of lateral traction though, not braking or acceleration.

indeed.

Both are important. Brake bias (on a non-ABS-equipped vehicle) is normally set at the factory with the assumption that all four tires are of the same type and equally worn (I almost said "have equal traction characteristics" but that would only be true for vehicles of which the tires are all identical from the factory; e.g. not a vehicle which uses different size tires front and rear.) Then a little more front bias is dialed in for safety, but of the rear tires are worn/hard enough that the difference in traction between front and rear exceeds that margin, then you can have problems. Now ABS-equipped vehicles can do weird things through software, like ignoring the rule of thumb that the brakes should be front-biased in an attempt to equalize brake pad wear, since the ABS will take care of the rear lockup problem. Theoretically. Still and all, if I were designing my cost-no-object dream car which would be driven by YT and professionally maintained by a highly trained mechanic at no cost to me, I would still stick to the traditional method of setting up the base brakes so that they would be properly biased, and then use ABS as an add-on after the base brakes were properly sorted. That way if the ABS ever failed, the car would be at least as safe as the cars I grew up with, not compromised.

The concerns about cornering are also important and equally valid.

nate

they'd have to be crazy to do that. abs has to fail safe, i.e. the brakes must continue to operate safely and like traditional brakes if the abs component fails.

i've heard bullshit from dealers about "rear bias" in an attempt to explain premature rear pad wear on the recent accords for example, but it's incorrect, and the wear rate returns to normal when old-style pads are fitted.