What could cause this unusual tyre wear?

Post anything that doesn't belong in any other forum, including gaming and topics unrelated to motorsport. Site specific discussions should go in the site feedback forum.
User avatar
DiogoBrand
94
Joined: Thu May 14, 2015 6:02 pm
Location: Brazil

What could cause this unusual tyre wear?

Post

My father recently gave me the car that used to belong to him (well technically it still does), and the unusual tyre wear caught my eye.

Image
This tyre has around 20k kilometers on it, it's a Pirelli P Z
ero Nero, dimensions are 225/50R17. It's currently at the front, but it has done some distance at the back as well, which explains the high wear on the inside since the back has a lot of camber. What I don't understand is, why is it that in the second and fourth grooves the TWI is already touching the ground, while the first and third are fine?

The tyre spent most of its life underinflated, since my parents aren't really careful with tyre pressures and it has done pretty much 50/50 distance in highway and urban traffic.

The car is a 2012 Chevrolet Cruze, and yes, these tyres will be replaced as soon as possible.

User avatar
Big Tea
83
Joined: Sun Dec 24, 2017 7:57 pm

Re: What could cause this unusual tyre wear?

Post

Assuming the geometry is right (my first thought)

Would it at some point have been on a corner with bad shock absorbers? Once the balance has been destroyed it can continue to 'bounce'.

I assume you have had it balanced, but it id then spun from the hub, not 'rolled' from the outside.
Another (way out) possibility, was it parked for a long while with one part of the tyre in the sun?

Another (way out) possibility, although you never see it these days, has it been repaired with a 'strip' inside?
One test is worth a thousand expert opinions

Maritimer
Maritimer
16
Joined: Wed Sep 06, 2017 8:45 pm
Location: Canada

Re: What could cause this unusual tyre wear?

Post

Probably toed out, shoulder is scrubbing every time the car moves

User avatar
DiogoBrand
94
Joined: Thu May 14, 2015 6:02 pm
Location: Brazil

Re: What could cause this unusual tyre wear?

Post

It wasn't repaired and the shock absorbers are good.

I'm assuming the wavy wear was caused by the fact that it ran at the rear, where the negative camber caused the wear on the inside, and the wear in the middle was caused at the front. For some reason this car seems to wear the tyres in the middle even though they spent most of the time under the manufacturer recommended pressures.

User avatar
Big Tea
83
Joined: Sun Dec 24, 2017 7:57 pm

Re: What could cause this unusual tyre wear?

Post

DiogoBrand wrote:
Sun Dec 02, 2018 7:47 pm
It wasn't repaired and the shock absorbers are good.

I'm assuming the wavy wear was caused by the fact that it ran at the rear, where the negative camber caused the wear on the inside, and the wear in the middle was caused at the front. For some reason this car seems to wear the tyres in the middle even though they spent most of the time under the manufacturer recommended pressures.
That is the obvious conclusion I think. I do not know what suspension set up is on that car, but weight in the back could exaggerate it if the body rides lower.
One test is worth a thousand expert opinions

User avatar
Phil
418
Joined: Tue Sep 25, 2012 3:22 pm

Re: What could cause this unusual tyre wear?

Post

I would have guessed that over the course of 20k, the tire has been subject to various different loads and pressures, causing uneven wear.

Too much pressure = car wears off in the middle of the tire.

Too little pressure = car wears off on the side.

Camber will also have a huge impact on how the tire wears out. The tire construction also plays a role there too.
Not for nothing, Rosberg's Championship is the only thing that lends credibility to Hamilton's recent success. Otherwise, he'd just be the guy who's had the best car. — bhall II
#Team44 supporter

User avatar
Big Tea
83
Joined: Sun Dec 24, 2017 7:57 pm

Re: What could cause this unusual tyre wear?

Post

@DB, can you just clarify this is just the one tyre? not the same both sides?
Digging deep in my mental data base, the only other thing that comes to mind is a badly worn/adjusted wheel baring, but you would notice that? (yes?)
One test is worth a thousand expert opinions

User avatar
strad
265
Joined: Sat Jan 02, 2010 12:57 am

Re: What could cause this unusual tyre wear?

Post

Too much pressure = car wears off in the middle of the tire.
Image
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss

User avatar
DiogoBrand
94
Joined: Thu May 14, 2015 6:02 pm
Location: Brazil

Re: What could cause this unusual tyre wear?

Post

Big Tea wrote:
Sun Dec 02, 2018 10:56 pm
@DB, can you just clarify this is just the one tyre? not the same both sides?
Digging deep in my mental data base, the only other thing that comes to mind is a badly worn/adjusted wheel baring, but you would notice that? (yes?)
I'll actually check if both sides look the same tomorrow.

And as for the ones saying the wear in the middle is caused by overinflation: The manufacturer recommends 32psi, and it has spent most of its life way below that since my parents aren't very careful with tyre pressures. So either the manufacturer is recommending a pressure that's too high, or there's something else causing this wear.

Publiclyzai
Publiclyzai
0

Re: What could cause this unusual tyre wear?

Post

he wear in the middle is caused by overinflation: The manufacturer

User avatar
Phil
418
Joined: Tue Sep 25, 2012 3:22 pm

Re: What could cause this unusual tyre wear?

Post

DiogoBrand wrote:
Mon Dec 03, 2018 1:57 am
And as for the ones saying the wear in the middle is caused by overinflation: The manufacturer recommends 32psi, and it has spent most of its life way below that since my parents aren't very careful with tyre pressures. So either the manufacturer is recommending a pressure that's too high, or there's something else causing this wear.
Let me try again:

At one point or another, the tire was most likely overinflated, causing excessive wear in the center. Then the tire was underinflated and in conjunction to the camber, caused excessive wear on the tire inside. Thus the outside of the tire is least worn.

You said yourself, the tire has run at least 20k and also been used at the front and rear. There’s reasonable assumption the tire has gone from at the very least correct pressure (most likely overinflated) to underinflated state, but i’d also guess there’s a chance at one point or another, pressures were increased in a routine check.

Also, an underinflated tire will be subject to all kinds of forces and deformation. Basically, the bulk of the load sits on the tire wall, but even so, there is a certain construction of the tire to take into account as well. What you are seeing as weird, isnt really that weird once you account for all that.
Not for nothing, Rosberg's Championship is the only thing that lends credibility to Hamilton's recent success. Otherwise, he'd just be the guy who's had the best car. — bhall II
#Team44 supporter

Manoah2u
Manoah2u
399
Joined: Sun Feb 24, 2013 1:07 pm

Re: What could cause this unusual tyre wear?

Post

Had zero nero's too before. great tires, grippy, but sensitive. they need perfect adjustment by the garage to have equalized wear. mine too had odd wear patterns. given, they had tiny walls due to the high rim size.
i noticed they responded very sensitive to the shape of the road. if the asphalt had 'wear' in it; it had the tendency to follow that line, far more than any other tires i've ran.

my favourite remain toyo proxes r888 and nitto nt05

i had dunlop direzza's too, i did enjoy those better in rainy conditions too.
so in the end they might take the top spot, but the toyo's were sensational in contact.
Dumpster sounds so much more classy. It's the diamond of the cesspools.

Jolle
Jolle
171
Joined: Wed Jan 29, 2014 9:58 pm
Location: Dordrecht

Re: What could cause this unusual tyre wear?

Post

Not a very strange wear pattern for a fwd car with wide tires. Due to the camber the load is mostly on the inside.