6G Celicas Forums

Ok so it's been a while since I've worked on cars for a living. My rears are showing two different types of wear patterns, in the form of cupping and inner tire feathering. The tires have always been noisy since I bought the car over a year ago, and I know the alignment isn't perfect. I post this up for a couple reasons: to get a second opinion before I dump some money into the car, and to educate some of the other guys on here about what all you can see just from how your tires are wearing.

Now in both pics you can see the dramatic inner tire wear in the form of light/dark sections, and you can somewhat see how there's a darker stripe across the tire where it is worn differently: this is where the tire is flat spotting/cupping, both my rears are pretty much 16 sided polygons lol.




Here's the educational part: the feathering on the insides of the tires is from the toe angles being negative, or toe out, meaning the wheels point outward when the car is moving forward. The cupping can be cause by a few different reasons: wheels/hubs out of line, unbalanced tires (usually REALLY unbalanced) or bad shocks/struts.

The cupping is what concerns me. I've never seen a cupping pattern this bad, the tire varies in tread depth from about 5mm to bald all the way around the tire. The struts aren't leaking and they pass the "bounce test", the wheels/hubs aren't bent or anything, and the wheels themselves are fairly well balanced. The only thing I can think of is the struts are bad, despite the usual factors.

Oh and if it matters the tires are Bridgestone Potenzas, don't remember the exact model number. They have been on the car a few years, have seen about 60k miles if I remember correctly from the PO's service records.

thats crazy man! i have no idea. i just wanted to let you know that thats crazy.

^^^^

somtimes i think the cupping could be due tire being off balance? I have seen wheels pass the balance test in the machine, but sometimes on the road they act as off due to imperfections on the tires themselves, or just being old.

i think its a combination of over inflated tires + bad wheel bearing.

If its bad toe in or toe out would just cause the tires to wear out more quickly. I have not notice feathering or cupping due to toe in.

Camber in the other hand can cause the tires to feather.

hope that helps.

how's the frame alignment and lug nuts torqued??

My car does the same thing. I've had the wheels aligned 3 times. I've replaced my struts 3 times already. I've given up and just started buying cheap tires. I'll keep up with this thread though, so I can eventually get that lined out.

you ever think that the rubber bushings in the tension rods (not sure what toyota calls them) are worn out and you need new ones? they are the rods that are attached to the rear knuckles and go forward. i'll see if i can get a pick if you need it.

Well from what I've learned in school camber itself doesn't feather the tires, it's how camber affects the toe angle that causes the feathering.

The tires are kept at 32 psi, and last I checked the bearings are still good but I will put it in the air and check again this week.




Frame is straight and lug nuts are all at 76 ft-lbs.




The trailing arms be what you're referring to?

I've considered before replacing all the bushings in the suspension, maybe with a switch to polyurethane bushings or something, but that's expensive and a pretty big undertaking (especially for a car that isn't on the track). Could help though, worn bushings can cause a lot of play in the suspension.

It could be something as simple as locking up the tires a few times to avoid an accident or something like that.

I had something similar happen to my tires towards the end but it was on the outside of the tire.
(Bald tires + snow + an off-ramp don't mix too well.)

I slid about 200 feet till I hit the curb gently at around a 15 degree angle going 40 mph.



Point being... any extreme breaking, especially if the tires were unbalanced or misaligned, or if you happened to lock em up at the point where they're unbalanced to the max, will cause something like this to occur.

I've seen flat spotted tires from locking up the brakes, but the flat spots are evenly distributed around the tire, so something is happening as the tire is rolling. Plus the car has ABS lol.

When I was a mechanic, to demonstrate to some of the newer techs why they shouldn't lock up the brakes when they brake check cars on the test drive, we took a Focus (that needed tires anyways) and locked the brakes up at about 60 and slid to a stop, then showed the apprentices the flat spots and how noisy the tires were afterwards.

Not that this has anything to do with what is happening to both mine and your tires, but I know that once a tire starts a wear pattern, it continues that wear pattern. That sucks, especially considering that a deer ran out in front of me on my drive home from buying new tires last time. Flat-spotted them 20 minutes after paying for them, and here I am, 30,000 miles later, and I still have flat spots on my tires. All 4 of my tires are doing the same thing that yours are, and I've been told it's just the toe, like you said. One tire shop attributed my uneven tire wear to blown struts right after I bought the car. They said they could check the car's alignment, and it would read just fine, but if you put some weight in the driver's seat, it made that strut sit down a little lower, putting pressure on the inside of the tire. I have replaced my struts since then, and the car still does it, so I think that shop was just trying to be a tire shop and trying to make some money. But like I said earlier, I am watching this thread closely. Tires aren't cheap and I'm on my 4th set in 3 years.

check for wheel bearing play, ive had the same problem in that same spot, turns out i had a busted l/r wheel bearing.

this is too obvious but get 4 tyres at a time, have your wheels balanced during fitment, and have a wheel alignment done afterwards.

remember that bridgestone potenza have a relatively short lifespan as its a high performance compound tyre. i ripped through a set within 3 service intervals without doing anything excessive.


wheel alignment will definitely help even the wear though.

That is true about putting weight in the driver's seat, and changing the alignment, especially on small lightweight cars like ours. When I do alignments I put about 150 lbs of sandbags in the driver's seat. BMW's have a very specific pattern of weight to put in the car to compensate for typical weight loads that would affect suspension geometry; the same is used for precisely aligning a car for track usage.

As for our cars, like you said the tires probably started wearing before I even owned the car, I'll check my service records but I do believe there was a bit of suspension work done between new tires and me buying the car, which could have been the cause. The toe angle is something I'm pretty positive on, mostly because my car is definitely out of alignment (pulls hard left thanks to some local road construction). I'm really trying to stretch these tires as long as I possibly can due to financial reasons, since the Celica will hopefully go under the knife soon and I'll get a different daily.

Very true, I got my RE92's with about 50-60% tread left in the middle of September. I checked the tire a few days ago and felt the wear indicators. But I've also been doing some good cornering and a few launches, so I haven't always been gentle.

Front left, Bridgestone Potenza RE92:


Rear left, Primewell PZ-900 (DEFINITELY down to the wear indicators):


This post has been edited by SwissFerdi: Dec 1, 2009 - 1:06 PM

that top picture the tire looks like it's still got 50-60% tread left. and the bottom picture the tire looks like it's still got about 3 or 4/32". You don't need to replace a tire until the tread is flush with the wear bar, which is 2/32"

Okay, thanks man, I appreciate that. I see what you're saying now, since there are a few millimeters between the tread and the wear indicator on the rears...and probably about five or six on the fronts. Learned something new today.

This post has been edited by SwissFerdi: Dec 2, 2009 - 10:52 PM

With your car lifted up try to pick the tire up. If you can move the tire up more than an inch your struts are bad. I have bad struts and the rear tires look just like yours. The other question is, how often do you rotate your tires?