[Surferdude]

Took these pics of the tyres we took off a CRDi i30 last week. Thought they'd be interesting to use in a little "diagnosis" lesson.
The driver complained about "wheel alignment issues" but didn't elaborate in a way which made sense to me. (You get that ).
The car had 43,000 klms up and I gather he'd had 2 or 3 alignments, using both a Hyundai dealer and someone else.

Anyway, the front tyres were obviously cactus.
The worst wear was on the inside shoulder of both tyres and if you look at the top left you can see just how badly they are worn. But there's also a tyre pressure issue as you can see there's also wear on the outside shoulder. The main point I want to make here is that if you look closely at the left (inside) shoulder you'll notice there's still some tread markings towards the bottom of the tyre whilst it's completely bald at the top.
It is a common misconception that this is caused by a tyre being manufactured "out of round". But this is not true. In this case and most where the tyre is worn like this, it is simply that the alignment has been so far out that, as it rolls along the road the grip is trying to tear the tyre off the rim (opposite where the shoulder wear is occurring). Obviously with pressure in the tyre, this can't happen so the tyre has to "snap" back into the straight ahead position. Cyclically over a period of time, this tends to happen at about the same spot on the tyre's circumference. Hence it wears more heavily in one spot and progressively less so around the tyre until you get 180 degrees from the worst part.
Depending on the strength of th esidewall in the brand of tyre concerned and how bad the alignment is, I've seen instances where the tyre is worn down to the belt on one side and still have a couple of mm of tread opposite it. Such an occurrence is worse if the tyre is toeing in and the wear is on the outside shoulder which also cops it on roundabouts.


This shows a cut in the tread from some object on the road. Sorry about the focus but you get the idea.



And here's a close-up showing just how bad it is.



This cut is down into the belt area and, if it had been there along time and there was more tread on the tyre, it would let moisture and grit into contact with the belts starting rust which will lead to a tread separation. As this was on the front you can appreciate how catastrophic a failure could have been.

A very good reason to have your tyres balanced regularly, allowing for off the vehicle inspections before you kill someone or at the very least, peel your mudguard off with yout tyre tread.

This one just shows the same things from a slightly different angle



Hope this is useful. Feel free to ask questions.

[Gibber]

I am guessing that the bearing on the wheel would take a hammering too!

Makes you wonder why it was so far out after two alignments, had the wheel been kerbed?

Sent from my HTC Desire

[Surferdude]

I am guessing that the bearing on the wheel would take a hammering too!

Makes you wonder why it was so far out after two alignments, had the wheel been kerbed?

Both rims and hub caps were unmarked. No evidence of any abuse. Just massive toe out sometime in the tyres' life. Actually the toe was pretty good by the time we got to it so I can only assume the last alignment was OK but the damage had been done.

[eye30]

Many many years ago a car I had was a sod to get the alignment correct.

I had been to several gargages and they would put it up on the ramp and use mirror type contraption to set the wheels up.  I was never happy with the end result as the car always seemed to to have a pull into the kerb.

One day I was passing thro' a small village.   I popped into the village garage.  The "old" chap said that he had a wheel alignment gauge which was placed on the ground and you ran the car over it. 
The wheels were altered and the car ran in a true line.

To this day I've never seen this type of gauge used again.

[Och_i30]

An old work colleague had a drive-over type alignment aid and I remember using it to check alignment on my old Peugeot 205.
It seems Gunson still market them.
http://www.gunson.co.uk/item.aspx?cat=664&item=1812
Or google search on gunson trackrite wheel alignment gauge
Also on ebay for £45.

[Surferdude]

That's interesting. I haven't seen one for many years (since my days at the track).
But I'm at a loss as to how the use of one would correct a car pulling to the curb as they only measure toe out/ in.
Toe won't cause a car to pull one way. If it's bad enough you might get a wandering effect where it wants to follow any depressions in the road.

But camber, and other alignment settings are what cause a car to pull one way. 
Can anyone throw more light on this?

[Och_i30]

I think we could do with a bit more snow before the end of winter so it's time to put the summer tyres back on ...
The summer's are the original Hankooks with approx. 15k miles on them.

Both of the fronts have the beginnings of shoulder wear on the inside edge like in Surferdude's photo, but one wheel is considerably more noticeable than the other. 
They both have 4-5 mm or tread except at the shoulder so there's still a lot of life in them.
The rears are pretty much as new with even wear.

Do I stick the rears onto the front and get the tracking adjusted, then return them to the rear?  (or leave them on the front for better grip in the snow ...?) 
Will the fronts wear down evenly with the inner shoulders scrubbed?

[Dazzler]

Do I stick the rears onto the front and get the tracking adjusted, then return them to the rear?  (or leave them on the front for better grip in the snow ...?) 
Will the fronts wear down evenly with the inner shoulders scrubbed?

Seeing as Trev is not on line.. I will give my 2 cents worth 

I would switch the better ones to the front and try and even things up a bit (plus it would be a bit safer) 

[Och_i30]

Hi Dazzler,

Thanks, I would usually do as you suggest and put the best tyres on the front but the tyre fitters in the UK now recommend the tyres with the most tread go on the rear.
(The argument being understeer is more intuitive to correct than oversteer and so it's generally safer to have understeer).

Of course near-bald tyres on the front might be a contributing factor to the chaos and gridlock we go through when we get a flake or two of snow ...

[Dazzler]

Does you i30 have ESP? that should keep you out of trouble until the tyres are down to the wear markers

Be interested to see what our resident expert (Trev) says..

[Surferdude]

I think we could do with a bit more snow before the end of winter so it's time to put the summer tyres back on ...
The summer's are the original Hankooks with approx. 15k miles on them.

Both of the fronts have the beginnings of shoulder wear on the inside edge like in Surferdude's photo, but one wheel is considerably more noticeable than the other.  Bit of a puzzle there. I would have expected if one had more shoulder wear than the other, the wear would have been on the outside shoulders and the worst being on the LHF - assuming you are in the UK. I assume your camber and castor are within tolerance? If you hav esimply a toe out problem, I would have thought both tyres would wear about the same amount
They both have 4-5 mm or tread except at the shoulder so there's still a lot of life in them. If you have 4mm left that means only a useable  2.4mm as the legal limit is 1.6mm. However, it depends on how strict the UK authorities are on measuring the tread. They may have a more lenient view than we do. I seem to remember tyres over there are legal provided a certain % of the tread width is legal. In Oz, the moment any part of the tread reaches a TWI, it's illegal.
The rears are pretty much as new with even wear.

Do I stick the rears onto the front and get the tracking adjusted, then return them to the rear?  (or leave them on the front for better grip in the snow ...?)  Now, the issue about fitting the better tyres on the front or rear is one which continues to generate heated discussion. There is a reliable line of thought which suggests it's better to have understeer than oversteer. However, my take on it is three pronged. 1/ Front whel drive cars naturally understeer anyway, so having the better tyres on the front will probably only reduce this effect, not create massive oversteer. 2/ Putting the more worn tyres on the front could produce steering failure as the less tread there is on a tyre, the more susceptible it is to punctures (or blowouts). There are some figures somewhere. I forget the numbers but it's something like 70%-90% more chance of punctures in the last 10% of the life of a tyre. 3/ Apart form emergency situations, a car is much more easy to steer and less demanding of the driver, with good tyres on the front.
Will the fronts wear down evenly with the inner shoulders scrubbed? They'll probably wear evenly across the currently level part, but you can't put back the rubber worn off the shoulders and that part of the tyre will continue to wear so you'll end up with tyres like the one in the pic.

[beerman]

They don't look too bad. At least the tyre was practically stuffed before the bad allignment killed them. If the tyre was new, it would be more of a worry.

Were they the original set?

40k seems to be the age they die....

[Surferdude]

They don't look too bad. At least the tyre was practically stuffed before the bad allignment killed them. If the tyre was new, it would be more of a worry.

Were they the original set?

40k seems to be the age they die....

Actually they are very bad but maybe the pics don't do them justice. If you look at the upper left hand side (shoulder) of the tyre in the first pic you can see how it's worn very rounded. Close inspection will show that, despite there still being some tread on the main part of the tyre, the bald section has worn down into the undertread, a soft, porous layer of rubber built in below the tread belt package as a sort of shock absorber. Because this tyre has worn in such a rounded fashion its gone around the outside of the belt edge, into a type of rubber which is not designed to be exposed to air, moisture or friction.

In short, VERY close to a major tread failure. Not sure how come it hadn't let go yet. Probably a credit to the quality of the build of the Kumhos.

[beerman]

There bad, don't get me wrong.....

But having replaced sets on the old XD that were well worn on the inside but had plenty to give on the outside (despite wheel alignments). I wouldn't be too unhappy to be ripping them off because whilst the inside is bad, the rest of the tyre is not that far behind. If you know what I mean.

If you want to see worse (and no doubt you have) take a walk through a Woodridge car park. Most of those cars would be off the road instantly, you'ld see more white belts than at an under 8's judo class.

[Och_i30]

Hi Dazzler,
Yes the UK i30's have ESP.  Can't say I've been in a position to see how well it helps when the rear is breaking away though.

Hi Surferdude, thanks for the advice,
I suspect a problem with camber angle but will find out next week assuming I can get the car booked in for a check.  The pot holes over here are the worst ever right now and when it's dark and wet they're a nightmare to spot.  I've hit some big ones where my first thought was I'm lucky they didn't rip the hub and wheel off.

There's a nice video of Vicki Butler Henderson demonstrating the front / rear issue on youtube

As usual it deals with the extreme situation though.

A difficult question to answer but roughly how far out does the camber / caster angle need to result in uneven wear like your example photos?

[Surferdude]

There's a nice video of Vicki Butler Henderson demonstrating the front / rear issue on youtube

As usual it deals with the extreme situation though.

A difficult question to answer but roughly how far out does the camber / caster angle need to result in uneven wear like your example photos?

If that's the bird from Fifth Gear, I won't be watching. God she annoys me. I've always said she sounds like she's having an orgasm when she's test driving a car. (Delete this if you want mods........Oh wait. That's me. ) And, as you say, only in extreme situations. Gives me an idea for another thread though. Might be interesting to see what people on here would prefer.

Good question as far as the seriousness of alignment settings. There's a whole host of factors which come into play here. Toe, camber, caster, SAI and so on. Then pressure and whether you're driving highway or city. The tyres in the pic had a toe out problem combined with a pressure issue (IMO). So by driving straight ahead, the tyres were trying to peel themselves off the rim to the outside, hence distorting the sidewall and putting excess loading on the shoulder of the tyre, and down into the upper sidewall area.

[Surferdude]

If you want to see worse (and no doubt you have) take a walk through a Woodridge car park. Most of those cars would be off the road instantly, you'ld see more white belts than at an under 8's judo class.

I spent several years as the manager of Goodyear in Springwood in the early 80's, and owned a house in Kingston at the same time so, yes, I know what you're talking about.

[beerman]

I've only had problems with aquaplaining from the front.....

But I was ahead of my time, I used to put new tyres on the rear. The theory being I would get 20k out of them before they went onto the front and risked getting chopped up with poor alignment......

[Surferdude]

I've only had problems with aquaplaining from the front.....

You've never had the back "step out" on you?

[beerman]

I have.....but that is usually either from putting the power down too early in a corner (deliberately or otherwise) or hitting a patch of oil or diesel at the wrong spot. Either way it is easily caught....

How does having tyres that are legal but not new on the front affect the bite of the front end when one is doing a full emergency stop and lane change? Will the older tyres be more prone to front wheel skid?

[Surferdude]

How does having tyres that are legal but not new on the front affect the bite of the front end when one is doing a full emergency stop and lane change? Will the older tyres be more prone to front wheel skid?

You've hit the nail on the head beerman. At least in my opinion. In both of those situations I'd rather have the new tyres on the front. Much better feel and more predictability. Also (in my experience) whether dry or wet.
But the question seems to be whether it's better to have a front end break away or a rear end slide. From what you've said above ("easily caught", I guess you're like me. Prefer a tail out situation.
I would have to say also in my experience with my kids and other young people I've been coaching at times, even if you haven't been told to, it seems to be natural to steer into a skid (ie. pull on some opposite lock), which is exactly the correct thing to do. Whereas, in an understeer situation people tend to wind on more lock and jump on the brakes which makes the situation worse.
I've found myself in the passenger seat twice over the years where the driver has panicked in an understeer slide. Once was on a wet road with an inexperienced driver and once was in a rally with my (now) ex-wife. Both times I've had to scream at them to get off the brakes. They have and we've stayed on the road.

[rustynutz]

I would have to say also in my experience with my kids and other young people I've been coaching at times, even if you haven't been told to, it seems to be natural to steer into a skid (ie. pull on some opposite lock), which is exactly the correct thing to do.

Up until my recent Defensive Driving Course I would've also said that this was the right thing to do, but, apparently this is only what you should do in a car without ABS. In an ABS equipped car their recommendation is to just stomp on the brakes.... 

I'm still not convinced.... :-\

[Surferdude]

I would have to say also in my experience with my kids and other young people I've been coaching at times, even if you haven't been told to, it seems to be natural to steer into a skid (ie. pull on some opposite lock), which is exactly the correct thing to do.

Up until my recent Defensive Driving Course I would've also said that this was the right thing to do, but, apparently this is only what you should do in a car without ABS. In an ABS equipped car their recommendation is to just stomp on the brakes.... 

I'm still not convinced.... :-\

Me either.
Have you ever done it?
Unless they've improved the system it feels like you're driving over violent corrugations - and the brake pedal is trying to smash your instep to smitherines. 
We did some tyre testing with Brad Jones at Winton a few years ago in an XR8 and he was doing panic stops with and without the ABS (special switch - it was a FoMoCo test hack). Definitely pulled up more quickly without the ABS. Yeah I know that's not for the great unwashed.

[rustynutz]

Haven't had the back step out as yet, Trev...but did plenty of hard braking and steering under hard braking at the course.
I was most impressed how well it pulled up and also how well I was able to steer. The ABS worked flawlessly, with only a slight rumble letting me know it was working. Can't recall feeling anything through the pedal, but then I was concentrating on pulling up before I hit the cones and watching out where I was steering. 

[beerman]

Rusty,

My advice in an ABS car was to stomp on the brake and stear away from the direction you are trying to go.

The theory being you slow the vehicle which assists you to catch the skid, then you attempt to steer where you want to go....The theory being the abs dosen't hurt anything, but slows you down reducing the amount of steering away you will need to do.

In reality for most people the adrenalin hits and they are in a world of hurt....All the modern stuff helps, but it is the ability to control the adrenalin dump that goes a long way to a successful outcome.

[Och_i30]

Changed back to summer wheels earlier this week so had a chance to look at both sets of tyres.
After 15k miles the summer fronts both have badly worn inside shoulders (no tread showing on the shoulder) but the rest of the tread is quite even.  I know the pressures were always 32psi or above,normally 35psi.  The winter set are showing signs of the same problem after 5k miles.  The alignment will be checked before the weekend and I'll update with photos and info. on the correction needed.

Re: ABS and ESP.  Had the chance to put both to the test in Germany last Christmas.  Was heading over a bridge in snowy conditions when car in front stopped at the entrance to a roundabout and I realized I was actually on snow rolled to ice.  Had to brake (no distance to engine brake) and ABS immediately kicked in as we slowly waltzed down a slight slope towards the rear of the car in front.  I realized we weren't going to stop in time so steered left (ABS still pumping away) in attempt to get some grip on bulldozed snow at the side of the road.  Luckily we did go left (I'll thank the ESP), the winter tyres bit into the softer snow and we stopped within a few feet, brown moment over.  Now the vehicle in front didn't need to stop and I didn't anticipate it would (that's what caught me out) so I swore quite a bit, but you can be sure I didn't get close to the tail of another vehicle for a good few days ...  But that was the first and only time I've tested ABS and ESP in anger (or fear!) and the front of the car is still in on piece!

[eye30]

Re: ABS and ESP.  Had the chance to put both to the test in Germany last Christmas.  Was heading over a bridge in snowy conditions when car in front stopped at the entrance to a roundabout and I realized I was actually on snow rolled to ice.  Had to brake (no distance to engine brake) and ABS immediately kicked in as we slowly waltzed down a slight slope towards the rear of the car in front.  I realized we weren't going to stop in time so steered left (ABS still pumping away) in attempt to get some grip on bulldozed snow at the side of the road.  Luckily we did go left (I'll thank the ESP), the winter tyres bit into the softer snow and we stopped within a few feet, brown moment over.  Now the vehicle in front didn't need to stop and I didn't anticipate it would (that's what caught me out) so I swore quite a bit, but you can be sure I didn't get close to the tail of another vehicle for a good few days ...  But that was the first and only time I've tested ABS and ESP in anger (or fear!) and the front of the car is still in on piece!

Now I wonder what would have been the outcome without ABS and ESP!!!!!


SPLAT!!!

[Surferdude]

Re: ABS and ESP.  Had the chance to put both to the test in Germany last Christmas.  Was heading over a bridge in snowy conditions when car in front stopped at the entrance to a roundabout and I realized I was actually on snow rolled to ice.  Had to brake (no distance to engine brake) and ABS immediately kicked in as we slowly waltzed down a slight slope towards the rear of the car in front.  I realized we weren't going to stop in time so steered left (ABS still pumping away) in attempt to get some grip on bulldozed snow at the side of the road.  Luckily we did go left (I'll thank the ESP), the winter tyres bit into the softer snow and we stopped within a few feet, brown moment over.  Now the vehicle in front didn't need to stop and I didn't anticipate it would (that's what caught me out) so I swore quite a bit, but you can be sure I didn't get close to the tail of another vehicle for a good few days ...  But that was the first and only time I've tested ABS and ESP in anger (or fear!) and the front of the car is still in on piece!

Now I wonder what would have been the outcome without ABS and ESP!!!!!


SPLAT!!!

Not only that but..... in the wrong.