Weird tire tread wear/feature

[crazyrog17]

I don't know what can of worms I'm opening by asking this...

My girlfriend's Mazda 323 is running on 13" steel wheels with a mismatched set of tires on it.

The front two, although not exactly the same, have even wear and look fine. They don't lose much air, but do lose a few pounds every month or so. I think it's pretty usual for their age.

The rear two are the ones I'm concerned about... They look like deep mud or snow tires. They've got less wear than the front on their tread, but the tread wear is... bumpy. It waves across the tread. When you run your hand around the tire it's like, I hope you can stay with me here, two opposite sine waves runing on the front and back of the tire.

I've followed her driving down the road and the wheels aren't wobbling on either side. The weird thing is it's the same on both tires. Is it part of the design of the tire?

I hope she can get new tires for it soon anyways... Just curious about it.

[Pu241]

Rear bearings are in need of replacement.
Do you hear an oscillating sound getting louder and increasing in frequency and amplitude as you increase speed?

It's not a hard job to do yourself, no press needed, but would be easier with one.

[crazyrog17]

Sorry, but no

I just drove it today, nothing weird like that. Just sounds like an exhaust leak and a rattling interior hatch panel, haha.

Any other difinitive tests for the rear bearings? I just did the drum brakes a month or two ago and they spun and sounded fine then. The wear was (very) apparent even before then. Both sides (with the wheels and tires mounted) spun for a revolution or two with a moderate push.

[Ephet]

the rims could be bent and off balance

[Ephet]

Rear bearings are in need of replacement.
Do you hear an oscillating sound getting louder and increasing in frequency and amplitude as you increase speed?

It's not a hard job to do yourself, no press needed, but would be easier with one.

hey on a scale 1 -10 how hard is it to do the bearing in the back? cuz mine needs it bad and im pretty good at doing all my own work.

[AlaskaFestivaGuy]

One member of my WA fleet made speed-proportional noises and was squirrelly at freeway speeds. A tire shop noticed tread patterns like you described and said the treads were starting to separate internally due to age.

One pair of new twelve-inchers later, I was pegging the speedo hands-off with no shakes or noises whatsoever.

[crazyrog17]

Sounds reasonable. I have no doubt these tires are any less than ten years old.

I looked at them again and it's not precicely 'sine waves', but just random and bumpy. I'm thinking AlaskaFestivaGuy is right.

[microflea]

Weak shocks/struts can also cause that condition.It's from the rear tires hopping in the rear when you hit a bump and they lose contact with the road.it will "chop" them.Also possible alignment issue.I'll bet it's out if you have it checked

[Pu241]

Sorry, but no

I just drove it today, nothing weird like that. Just sounds like an exhaust leak and a rattling interior hatch panel, haha.

Any other difinitive tests for the rear bearings? I just did the drum brakes a month or two ago and they spun and sounded fine then. The wear was (very) apparent even before then. Both sides (with the wheels and tires mounted) spun for a revolution or two with a moderate push.

Jackup rear of the car and support it safely.

Hold the tire in the 12 and 6 position and try to wiggle it.
Then hold it in the 9 and 3 position and try to wiggle it.
There should minimal, if any movement.
The bearings, though bad, may not always make a noise.

[FestYboy]

Weak shocks/struts can also cause that condition.It's from the rear tires hopping in the rear when you hit a bump and they lose contact with the road.it will "chop" them.Also possible alignment issue.I'll bet it's out if you have it checked

i'm with you on this one... weak shocks and then resulting imballance will cause this and it'll ge worse, faster, as time wears on. replace rear struts, tires, and align car. problem fixed.

John, never seen a bad bearing do what's being described to the tires. i've also noticed a trend of rear shocks/struts failing before fronts though the fronts are under more stress... hmmm.

[batstiva]

John, never seen a bad bearing do what's being described to the tires. i've also noticed a trend of rear shocks/struts failing before fronts though the fronts are under more stress... hmmm.

Come to think of it, the last time I did shocks/struts all the way around, it was my rears that really needed it. Just did the fronts cause, well because.

[AlaskaFestivaGuy]

My tires were only about 7 or 8 years old.

After this and several similar experiences (including sidewall bulges appearing on NOS snow tires), I won't do freeway driving on old tires like this. If one were to discombobulate in the fast lane while passing a semi, things could get pretty ugly fast.