Rear Left Tyre Wear

[Ralph1Malph]

Hi All,
Looking for advice, or support or maybe, just sympathy!
My rear left tyre is wearing at and alarming rate. It'll need replacing very soon, as the outside is scrubbed. The other three are wearing evenly and are maybe at half life only.
I do need to replace the sway bar bushes as I'm sure they're shot, but is there a common issue with just that side?
There is a noticeable clunk when going over potholes and speed humps etc, but it's both sides hence sway bar IMHO.
Could the alignment be out on just that side?

To make it more annoying, the rubber is 265/60 but the spare is 255/60 so don't like having it on for a long time.

Any advice appreciated.

Ralph134049134050134051134052

[DiscoJeffster]

Hi All,
Looking for advice, or support or maybe, just sympathy!
My rear left tyre is wearing at and alarming rate. It'll need replacing very soon, as the outside is scrubbed. The other three are wearing evenly and are maybe at half life only.
I do need to replace the sway bar bushes as I'm sure they're shot, but is there a common issue with just that side?
There is a noticeable clunk when going over potholes and speed humps etc, but it's both sides hence sway bar IMHO.
Could the alignment be out on just that side?

To make it more annoying, the rubber is 265/60 but the spare is 255/60 so don't like having it on for a long time.

Any advice appreciated.

Ralph134049134050134051134052

I have a similar issue. Rear left. Outer edge feathering and wearing faster than the rest. I’ve wondered if it’s a worn bush or alignment. Still haven’t got it aligned to find out.

[Tombie]

Assuming there is no suspension wear at play...

Do you have a lot of roundabouts in your usual area of driving?

We would wear the LHR of the D2 quicker than all the others also, until we moved to a different city and had less roundabouts...

Serious!

[vee8auto]

Hi All,
Looking for advice, or support or maybe, just sympathy!
My rear left tyre is wearing at and alarming rate. It'll need replacing very soon, as the outside is scrubbed. The other three are wearing evenly and are maybe at half life only.
......
Any advice appreciated.

Ralph

Another factor that will cause weird tyre wear is if the air suspension calibration is out of whack. My D3 experienced rapid wear on 2 trips towing a camper trailer. The left rear tyre went bald on the inner edge.

When I checked the height calibration it was obvious to me that the left rear air strut was holding up the rear of the car and the right air strut wasnt doing a great deal, which also explained some pretty funky handling behaviour.

It might not be the cause in your case but it was with mine.

[Ralph1Malph]

Another factor that will cause weird tyre wear is if the air suspension calibration is out of whack. My D3 experienced rapid wear on 2 trips towing a camper trailer. The left rear tyre went bald on the inner edge.

When I checked the height calibration it was obvious to me that the left rear air strut was holding up the rear of the car and the right air strut wasnt doing a great deal, which also explained some pretty funky handling behaviour.

It might not be the cause in your case but it was with mine.

I've actually considered this as I fiddled with both the calibration and height over the last 6 weeks. That said, I've measured it and it is pretty close to the mark I reckon, 466 front and 485 rear.

That said, I'd actually like to 'reset' both the calibration and ride height as I have no idea if it's right other than the measurements. Eg, I could have the calibration -10 and th ride height +10 and no way of telling etc.
But, true to form, I can't find a reset process I like. I do have a IID GAP Tool so .....

Cheers
Ralph

[vee8auto]

ok, as you have acknowledged, the measured height is no indication of the calibration.

You can view the calibration settings in the GAP IID Tool, and they should be closely matched across each axle, but not front to rear. I will try and find a previous post that I did, it explains it better.

edit: here tis
Nanocom evo - height calibration (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/253341-nanocom-evo-height-calibration.html)

[Ralph1Malph]

Thanks vee8auto, I'll have a poke around and give it a crack.

FWIW, here's a screenshot of my current values, yes, there is a big variation across the rear.
Car is parked on a bit of a sideslope and I was not in it.134056

Cheers
Ralph

[letherm]

I had the same problem following a bad wheel alignment after hitting the rear left against a round about kerb. Asked dealer to check for damage out of caution (there was none) and his local wheel alignment source did the alignment. Following this the car pulled slightly to the left and the rear left tyre scrubbed the outside edge. Took it to an indy LR specialist and he found that the rear was out to blazes. Now runs straight as a die and no more unusual wear issue. So your problem may be simply alignment. Then again it may not. The joys of owning a car.[biggrin]

Martin

[vee8auto]

Thanks vee8auto, I'll have a poke around and give it a crack.

FWIW, here's a screenshot of my current values, yes, there is a big variation across the rear.
Car is parked on a bit of a sideslope and I was not in it.

Cheers
Ralph

The 'Calibration Value' is the fudge factor that i referred to in the other thread. Mine was the same, it appears that someone cranked up one side, so that side is doing all the work. There are a number of other variables but for now just pay attention to the procedure I detailed, and dont delete any steps.

But the 'seat of the pants' test is the speed hump test (in the other thread ) and if one side wallows down, in your case the right rear, then it would confirm that the left strut is doing all the work, hence tyre wear.

Anyway, you have your 'as found' figures so if you get lost in the process just put those calibration constants back in and have a rethink, or start again.

But as Tombie mentioned, lotsa round-abouts are another factor, but from your as-found calibration constants I reckon this now needs a better look at as well.

[DiscoJeffster]

Well you know I’d not considered that one side might be propping the other but now looking at the values that I have from the last guided calibration, that might be my issue too. I’ll do as you say and reset them all to 190 odd, then take it for a drive to settle it, then run through a guided calibration and see what it comes up with.
https://www.aulro.com/afvb/images/imported/2017/12/727.jpg

[vee8auto]

Repeatability is the potential chaos factor in this process, so the setup steps such as full tank of fuel and recommended tyre pressures are important.

Also, the step: Put it in Tight Tolerance Mode. Raise the car to off-road height, while rolling slowly, then lower to normal height while rolling slowly. .. is all about controlling mechanical hysteresis, which is a real thing when setting up positioning actuator control loops.

[Ralph1Malph]

I had the same problem following a bad wheel alignment after hitting the rear left against a round about kerb. Asked dealer to check for damage out of caution (there was none) and his local wheel alignment source did the alignment. Following this the car pulled slightly to the left and the rear left tyre scrubbed the outside edge. Took it to an indy LR specialist and he found that the rear was out to blazes. Now runs straight as a die and no more unusual wear issue. So your problem may be simply alignment. Then again it may not. The joys of owning a car.[biggrin]

Martin
You may be onto something here as well as I have noticed it pulling to the left more recently.

[letherm]

Repeatability is the potential chaos factor in this process, so the setup steps such as full tank of fuel and recommended tyre pressures are important.

Also, the step: Put it in Tight Tolerance Mode. Raise the car to off-road height, while rolling slowly, then lower to normal height while rolling slowly. .. is all about controlling mechanical hysteresis, which is a real thing when setting up positioning actuator control loops.

I just googled that as I've never heard of it. Decided to get a degree in something so as to try and understand what it means. I must be dumb or something. :wallbash:

Martin

[vee8auto]

I also googled it before posting comment but couldnt find a good explanation.

It is a concept to do with mechanical engineering and industrial instrumentation and control. It describes the drag or load in a (hydraulic or pneumatic positioning) system that creates an error which is dependent on the direction from which the device is driven.

Otherwise described as the concept of overshoot or undershoot depends on the direction from which the object has been moved by the actuator, or driving force.

If not factored in when trying to calibrate a positioner to tight accuracy you will end up chasing your tail.

[Ralph1Malph]

Ok, I didn't get to start Mr vee8's calibration process yet, but I did fiddle with my IID tool some more!
I reset the rear calibration to 190 and noticed (not unexpectedly) that the ride height is now 30-40 mm difference left to right. Mmmm strange I thought but then I realised that when the ride heights were the same, the calibration was different by this amount (as per the previous pic), so not unexpected.
So I deflated all corners for a look and found that fronts were both the same, yet even on the stops, there was 30-40 mm difference in height L-R on the rear.

As I said, I do have to replace at least the sway bar bushes, but I am starting to think that there must be some damage or hefty component (bush) wear to account for that much difference.
Being a graphical kind of guy, I went for a drive whilst watching the height graph and IMO, both rear sides went up and down by the right amount when they had to. I mean by this that when going over a speed hump, both rear sides contracted by the same amount then extended and contracted again by the same amount each side.

Tomorrow, I'll do Mr vee8's calibration, but I fear I'll be up for bushes or an arm.

Cheers
Ralph

[DiscoJeffster]

I also had a play, at least until the compressor overheated and found that I ended up back near the original settings. I do wonder why I have the disparity left to right however they’re only numbers related to the output value of the height sensor so it’s not the end of the world, unless it relates to an issue, and if it does, I’m stumped as to what.

[Tombie]

And if you change the sensor it will be different again.. just a tolerance thing!

[vee8auto]

Ok, I didn't get to start Mr vee8's calibration process yet, but I did fiddle with my IID tool some more!
...
So I deflated all corners for a look and found that fronts were both the same, yet even on the stops, there was 30-40 mm difference in height L-R on the rear.

As I said, I do have to replace at least the sway bar bushes, but I am starting to think that there must be some damage or hefty component (bush) wear to account for that much difference.
....

Cheers
Ralph

when you say 'ride height' are you measuring axle centre to top of wheel arch?

And yes, if something is badly worn or bent then thats your most likely cause. I only suggest checking your height calibrations when nothing else is making sense.

Also, after all my control arms were replaced and before getting the wheel alignment I did a height calibration , and after wheel alignment I rechecked it.

[Ralph1Malph]

I carried out a recalibration to the best of my ability. Then, I obtained a second hand tyre as mine was scrubbing badly. As it turns out, when the tyre guy removed it, we could plainly see it was out of round! The wear difference was stark! Second hand tyre is a HT so harder, but seems to be wearing well thus far and the ride is definitely smoother. I suspect that the out of round tyre was at least partly culpable.