tire pressure/wear on 08 Impala?

Hi all,
just yesterday I had two new tires installed on my company car, to replace the original Goodyear Integrity tires. I did not have this car from new but "inherited" it at about 16K miles. It now has about
27K miles and the tires that were on the front were not only badly worn but had gone out of balance. I had the tires rotated at 21K miles (and it appeared that they had been rotated previously at about 14K miles) and had them balanced and the alignment checked at that time. The tires were worn in a pattern that indicated underinflation, but I'd actually been running them at higher than the recommended pressure (33-34 PSI not 30 PSI as recommended) because the car was very floaty and imprecise at the recommended pressure and also the front tires appeared to be very "squashed" at 30 PSI. The tires that are currently on the rear are not quite worn enough to warrant replacement (according to the fleet people) but are not far from it.
From looking online it appears that the Integrities still suck like few tires suck... I had a set on my last company car and hated them on that car as well, although that set wore like iron and I had to wait until about 50K miles to get those replaced. But it sounds like others are reporting this wear pattern and unusually fast wear rate from reading the reviews on tirerack.com.
Question is this - is the problem with the tires, or with GM's tire pressure recommendation? New tires are Michelin Symmetry, and I'd like to do right by them because I've never had a bad set of Michelins. I have in fact sent an email query to Michelin to see if they publish load/recommended pressure charts for these tires but I kind of expect that they will say "follow manufacturer's recommendations." Or is the newer Impala just a tire eater by design?
thanks
Nate
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Front tires on larger heavy front wheel drive cars tend to wear much fsater than the rear tires. Where and how you drive also has a major impact. My ex-wife could destroy a set of front tires in a year - she only drove on surface streets and couldn't hold a straight line no matter where she drove. Many local surface streets were highly cambered rock and tar construction. Combining her driving style, street construction, and driving patterns, and it was a wonder the tires lasted as long as they did. And it didn't seem to matter whether the car was front or rear wheel drive. She would scuff the outside tread off the front tires. My son can also destroy tires in a matter of months. He is an agressive driver. My older sister never wears tires out...I mean it is unbeleiveable. She owned a late 70's Accord that went to the junk yard with the OE tires. The car was a rust bucket, the engine was leakig oil like crazy, yet the tires still passed inspection with 80k miles on them. I'm somewhere in between. I generally give up tires because they start bumping before I wear the tread out. 60k miles is about when I replace them becasue they just start to adversely affect the ride and comfort.
I'd go with the correct OE (Chevy) recommended pressures. Looking at the sidewalls is a poor indication.
Ed
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it sounds like

I study those TireRack reviews like homework when I am buying a new set of tires, Nate.
If you find a lot of reviews complaining about wear, I suspect the tires. I am very leery of all American tires right now.
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I am very much a fan of some American tires... but those tires... they are really awful. They exist so that car manufacturers can ship cars with tires on them without having to actually pay money for good tires.
If the wear pattern indicates the pressure is too high, it is indeed possible that you need to reduce the pressure to get even wear. However, if you have a choice between even wear or better handling, going for the better handling is probably a smart choice.
It's also possible that you aren't loading the car as heavily as the folks at Chevrolet expect you to be doing. Maybe you should go to the bad Chinese buffet and gain a couple hundred pounds.
Get the fleet guys to put ANYTHING else on there. Those things are just horrible. You don't want to die. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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On Sep 17, 2:24 pm, snipped-for-privacy@panix.com (Scott Dorsey) wrote:

I'm going to try to reply to a couple different comments in one post, so Scott, don't think I'm losing it if what I say isn't a direct response to your post...
first, I don't know that driving habits have a whole lot to do with it because my previous car was also an Impala (albeit previous generation - but my understanding is that the basic chassis is still basically the same) and those tires lasted forever. I'd say my driving is 50/50 highway and surface streets. I would think "aggressive" driving would only wear the outside edge of the tires; these tires were worn about equally on the outside and inside edges, maybe slightly more on the outside, but not much.
second, it wasn't that the tire wear indicated *over* inflation, it was that I was "overinflating" the tires per the placard on the door post but the tire wear is still indicating underinflation. that's why I'm wondering if the Integrities tend to wear like that in general (but then why did my old ones not do that, or does Goodyear's consistency from batch to batch suck as bad as the quality of their tires?) or should I continue to "overinflate" my new tires, perhaps even increasing pressure?
FWIW it's raining today and the Michelins are a VAST improvement. The exit from my office is onto a 55 MPH road with very heavy traffic and there's no light there, so "brisk" acceleration while turning is usually indicated there. No tire squeak today when I left for lunch. Right now they're at 34 PSI, but I'm just not sure if that is optimal or not, and I'm looking for a shortcut to experimenting with them, if there is one.
nate
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Get a white China marker and draw a line across the tire. Drive around the block. Did the line wear evenly across the face of the tire? If not, alter the pressure as indicated.
Michelin makes a few awful tires too, but I have nothing but great things to say about the Hydro-Edge or the Pilot Exalto. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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There are may factors working against the front tires on a fwd car.
One thing that causes wear is that they are always set with toe-in alignment. This will always eat the outside edge of the front tires. This takes the play out of the sidewalls of the tires for faster steering response, and when under heavy braking the toe angle becomes less extreme which gives better braking traction. Under heavy acceleration, the toe-in becomes even more extreme. So if you're driving on the highway the wear will occur much slower. If you have to race taxicabs to the next traffic light every day, the outside edge will wear much faster.
If it is really costing you too much, if this is the problem, then there is a way to improve the longevity of your tires. All cars are given a margin in their alignment specs. Technicians can adjust the alignment within those specs without any serious problems. So have it aligned to the very least acceptable toe-in, and your tires will last longer. You may notice an improvement in gas mileage also as there will be less rolling resistance. The down side is that you will feel a little more play in the steering. That is because you' will have taken some of the tension off of the outer side-walls of the tire. Everything's a compromise.
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If the tires wore/looked worn from under-inflation, then they were under-inflated. Run more air and keep an eye on them. Don't make more out of it then what it is.
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Okay, underinflation to me shows wear at the edges, less in the center. Overinflation shows wear at the center, less at the edges. Scalloping can be a number of things, but I have noticed that it can occur nowadays simply because you dont rotate your tires often enough.
The last tires I bought for the Avalon were Kumho Platinums. I dumped the Michelins which were excellent tires, but had just worn out too quickly. The OEM Michs had a 440 tread wear rating.
The Kumhos were rated 700 or over, 168 mph, and had an assymetrical tread design which was supposed to reduce noise,among other things.
These are Korean, and were purchased for about $40 per tire less than the Michelins.
So far, excellent. They have no particular wear yet.
I fell out of love with Goodrich a long time ago.. Firestone too. I had some good Goodyears, but also had some terrible ones...the Eagles.
Some of these brands had belt problems, roundness problems, etc. Just not very good at all.
Used to be, running your tires 3-4 psi over the printed rating didnt hurt anything. You might get slightly better mileage, grip, and tire life. Slightly harsher ride. Dont know if that has changed.
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yes, exactly. they were bald outside the last rib on both inside and outside, but still had plenty of tread above the wear bars in the center of the tires. No scalloping that I could notice, maybe a tiny touch of feathering but really just weird wear that looking at it suggested severe underinflation to me, but I know that I'd never let them get that way. I have checked all of the tire gauges that I own and they all read within a PSI or so of each other, and the TPMS readouts correlate similarly.
nate
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