[BrendanP]

I've just replaced the rear tyres on a 2011 CRDi as the inner shoulder has been scrubbed off down to where the cords are showing. The wear pattern is the same on both sides. The car has done 242000 miles and these tyres have been on for 45000 miles. The front and rear wheel alignment was set about 3 months ago and a lot of the wear took place before that. Rear shock absorbers were replaced 4 years/90,000 miles ago.

I intend to check the tyres in a month or so to see how they're wearing. Any ideas on what else might be causing this? Is it possible the rear springs (which are original) are tired causing the rear suspension to sag so that the tyres are running more on the inner edge?

[Surferdude]

If the suspension was sagging due to soft springs it would show up during a wheel alignment.

Assuming they lived all there life on the rear, it would certainly indicate a camber problem. Do you have to figures from the recent wheel alignment. As you say, most of the wear could have happened before the alignment. And once the rubber is gone, you can't put it back so where the wear (see what I did there?), was will still wear out first.

But if they started life on the front, that wear pattern could be from serious toe out causing the sidewalls to distort even in the straight ahead position.

So yes, keep an eye on them. Just make sure you measure all across the tread face accurately. And look out for any feathering on the shoulders. That's the first indication of misalignment.

[TerryT]

If the suspension was sagging due to soft springs it would show up during a wheel alignment.

Surferdude, yes, agree. A question, please. 

If the vehicle was just given a basic wheel alignment three months ago (on already excessively worn inside shoulders) and the springs were not checked/replaced (at 242,000 mile/390,000 km life) IF the springs were worn wouldn't they start to affect the rear alignment and accelerate the existing damage to the tyres...which is what happened, yes? 


You said:  "...make sure you measure all across the tread face accurately."  What are you measuring?  Tread depth?

Cheers, TT

[Surferdude]

I guess of the springs were soft, they might have an effect but I wouldn't think it would be anything like what your photo shows, unless you regularly had weight in the back. ie. Adult.rear seat passengers and or heavy luggage in the boot.

As for measuring, yes tread depth. If you're starting to get uneven wear, it'll show up in tread depths long before it's visually obvious. A difference of as little as a half mm would indicate a problem.

[Surferdude]

Just had another look at that tyre. That's extremely serious shoulder wear.
Something's not right.

[eye30]

Is there any evidence of the tyre rubbbing against any part of the car or within the wheel arch etc.

When was the last MOT?
Must be very recent wear as I've had advisories re tyre wear noticed by the tester.

[BrendanP]

At the last MoT they did comment on the wear but it hadn't worn through to the cords. That was almost 10,000 miles ago (this car does about 25,000 miles/year), and the tread across most of the width is good. You could feel scalloping on that shoulder, and you can see where the rubber has worn off it's at a regular spacing. I had a similar issue at 150,000 miles where the Hankook tyres wore away at the shoulder, I replaced the rear shocks then because there was a 'thrumming' sound from the rear wheels which went away when I replaced the shocks (with Monroe). The latest tyres are Goodyear. The wheel alignment was done on spanking new laser equipment, it wasn't a back-street bodge.

The tyres have always been on the rear axle, the fronts wear nice and even, and it's almost always just the driver in it.

[Surferdude]

I think I'd be getting another wheel alignment just to be sure and let them see that picture.
Also, get a printout of the readings.

[TerryT]

I guess of the springs were soft, they might have an effect but I wouldn't think it would be anything like what your [BrendanP's] photo shows, unless you regularly had weight in the back. ie. Adult rear seat passengers and or heavy luggage in the boot.

Surferdude, I agree.  My thought that worn springs could be the issue was based on them being mega-shagged and for over a long period.  Improbable, but?  (And, that should have been obvious from a poorer ride quality and handling, bouncing over bumps and potholes etc).

Brendan had new shocks fitted four years ago but...depending on their quality, their mileage and the number of potholes and gutters challenged, they could still be the issue.  Improbable, but?  (He fitted Monroe's which are a known brand but faulty batches do happen and that, coupled with still using his old oem springs, could do it?).

When I first saw Brendan's photo, my immediate thought was that's some "crazy excessive rear camber and/or rear negative toe (toe out)".  But that surely would cause a relatively consistent 'feathering' wear pattern around the shoulder...not the brutal jagged pattern he has i.e. chord showing,  chord not showing.   So, improbable and Brendan said the workshop used modern alignment equipment so they should have got the settings right. 

The inside of the tyre rubbing against something or being hit by something when the vehicle is being driven?  (See eye30 post, I like this theory).  You could think improbable because that's usually fairly easy to detect visually (proximity, shiny, scratched or rubber smear on the offending part), and by say, bouncing the rear suspension etc.  And, Brendan's wheel aligner should have been seriously looking for any underbody interference that could have been the cause of the substantial shoulder damage on the tyre when the vehicle came in.   

“Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” - Sherlock Homes”


You also said:  "As for measuring, yes tread depth.   Thanks for the clarification.

Cheers, TT

[Surferdude]

I think if the tyre was running enough to do that over the life of the tyre he'd have witnessed a lot of smoke in his mirror.
There's also no evidence on the rubber of overheating.

As for the uneven wear, that's normally just due to the (in this case) extreme distortion of the tyre casing by whatever is having an effect on it.
Because the tyre keeps trying to regain its correct shape, it'll actually drag across the road surface. That sets up a cycle which means the wear looks like it does in the photo.

[Surferdude]

Incidentally this is what that tread pattern should look like. Here on the rear of my Corolla.

[TerryT]

I think if the tyre was running enough to do that over the life of the tyre he'd have witnessed a lot of smoke in his mirror.
There's also no evidence on the rubber of overheating.

As for the uneven wear, that's normally just due to the (in this case) extreme distortion of the tyre casing by whatever is having an effect on it.
Because the tyre keeps trying to regain its correct shape, it'll actually drag across the road surface. That sets up a cycle which means the wear looks like it does in the photo.

Thank you for that explanation, Mr Tyre Guru. 

[TerryT]

Incidentally this is what that tread pattern should look like.

Hard to tell them apart.