Michelin tyres need replacing after 4k miles ?

Joe_Horner

Thanks, I was looking back at my previous posts thinking I must be going blind for a minute there

ChumpusRex

drofluf62 wrote: »

Thanks for all the comments.

I'm not sure how a general motorist can know if the tracking is done properly by the garage? And as for suspension and balance, well it has been regularly serviced as recommended, and being very experienced drivers we have noticed no issues

Unfortunately, you can't tell if tracking is done right.

However, "tracking" is a very basic, limited adjustment. Suspension and steering geometry is extremely complex - with as many as 13 different parameters that need to be checked. Tracking only checks one - the front "toe" angle. The other issue is that "tracking" is often measured using poor quality, manual equipment and therefore these measurements are often badly inaccurate. I've had two cars made much worse by having the "tracking" done, I'd guess because the garage's equipment wasn't correctly adjusted.

The front "camber" angles are often important in causing tyre wear, but sadly, these are rarely adjustable. If they are off, it is because something in the suspension is bent or worn.

One way of getting better service is to find a garage that can do a full "4 wheel alignment" using a modern alignment machine. These machines can measure every single parameter in the suspension and steering, and they will give a before and after print-out, so that you can see exactly whether there was a problem and what the garage has done about it.

Of course, if you have a camber problem, and your car doesn't have adjustable camber (most don't), you'll get an explanation why your tyres are being eaten, but there's nor much you can do about it (except modify the suspension to provide adjustment, or replace components).

Unfortunately, 4 wheel alignment is often expensive - £50+. I'm loathe to pay for it, but I once took my car for tracking, and was told by the garage that it was severely out. However, when i got the car back, it was terrible, pulling to the left like crazy and almost undriveable. I took it back to the garage, and they said the tracking was perfect and there was nothing they could do.

So I took it for 4-wheel alignment at another garage, and the mechanic showed me the printout from their specialist laser machine, which showed that the front "toe" (which is what was adjusted in tracking) was so far out, that he reckoned the tyres would have been destroyed in about 1000 miles. Not only that, but both rear wheels were pointing to the left, which was why the car was pulling.

Joe_Horner

Tracking's one of the few things I'd use one of the national chains for. In fact, just got the 525 sorted at our local ATS today. It had eaten the outer shoulders on the tyres it came on,plus the steering wheel was obviously mis-centred and I'd replaced a track rod end a month or two back.

£35 covered 4 wheel check and front tracking adjustment - just as well really seeing as the n/s was toed in by a full 10 mm too much so the new tyres would have been unhappy pretty soon :eek: The surprising thing was that the car actually drove ok like that apart from the tyre wear and off-centre steering wheel!

It's also quite nice that their system (apparently common to all their branches) has a monitor (and free coffee machine) in the waiting area which displays the readings, and the book figures, as they go. Obviously, it assumes they've attached the kit right, but unless you do it yourself you have to have some trust somewhere!

colino

Joe, your fitter must have been joking if he said it needed 10mm of adjustment. It would have been squealing round corners with a permanent tug on the steering wheel.

Joe_Horner

colino wrote: »

Joe, your fitter must have been joking if he said it needed 10mm of adjustment. It would have been squealing round corners with a permanent tug on the steering wheel.

Nope, that was the reading from the display and, as I said, as long as they fit the kit properly (got no reason to believe they hadn't) the kit won't lie.

The only noticeable effects on road were the wheel being about 30 degrees off centre for straight ahead, l/h indicators unreliable cancelling (because of the off centre wheel), and a tendency to jump towards the left if the l/h wheel hit bumps enough to unsettle it (not helped by a slightly weak shock absorber on that corner - the next job ) Oh, plus outrageous tyre wear on the outside edges.

All the symptoms have gone since adjustment (obviously don't know about the tyre wear yet but it should be better!) so no reason to think he got it wrong.

I was surprised it was that far out (and that the error was on the side that I hadn't changed the bll joint!) but apparently that chassis is pretty forgiving.


eta: That's another reason I like their "waiting area" display - if he'd just come through and told me it was that far out I would have been doubtful to say the least!

colino

Unless it was an American machine, who do tend to measure "total toe" (which sounds like a quaint term of abuse) in mm, or more usually inches, what you were looking at was either 10 degrees (still a lot) or less likely 10 minutes or 10 seconds of deviation. If it was 10mm, "out" the fitter would have had a bother pointing the car onto the ramp and you really would have felt it driving, especially on a 5 series..

Joe_Horner

Nope, considered that.

But the display had camber and caster "properly" diplayed as x° y' z'' but toe was shown as a decimal and "mm" after it. The centre of the displayed range (1.11mm) also corresponds to a toe angle of 0° 10' 0', which is the correct angular spec for the car.

So, it was 10mm out (incidentally, 10 degrees on a 15 inch wheel would be 66mm, and it wasn't that bad!!!)

Bear in mind that not all cars "pull" with incorrect toe-in because all it does directly is change where the wheel sits for straight ahead. Any obvious pull at the wheel from tracking issues is actually down to the power steering trying to centre the wheel rather than the alignment error itself. In fact, without power steering, no car will pull because of incorrect toe. All that happens is you have to turn the steering wheel to some odd angle to go straight.

Excess toe-in will tend to make the wheels "self-centre" to run straight, regardless of where that puts the steering wheel (toe is actually more effective than caster for this because of the way it varies with lock), and that can overcome the centering effect of the power steering in many cases.


eta: Excessive toe out is different, and will usually cause a pull with power steering because it reduces the natural centering effect of the wheels and allows the power steering to centre the steering wheel more easily. Without power steering, excess to out will make the steering "light" and tend not to centre at all.

colino

Sorry Joe, no time for a tutorial, but equal toe in or toe out, to any degree, if it is equal on both sides from dead ahead will make a vehicle naturally steer straight. If it deviates to one side (even if the, "total toe" is correct") it will scrub and lead steer.

Joe_Horner

Not to worry, colino, I really don't need a tutorial on this stuff.

Within likely limits (in this case up to at least 10mm difference), the only significant direct effect of uneven front toe is to cause the wheels to centre with the steering rack off to one side or the other - it effectively corrects itself dynamically under normal suspension forces unless you hold the wheel "straight" to prevent it. Rear toe is different because the only way that can "correct" itself is by the whole car turning.

Pulls to one side or the other are generally caused by one or more of the following:

Incorrect caster giving uneven self-centering forced on each side
Incorrect camber preventing tyres from making "flat" contact with the road (so they act like cones instead of cylinders)
Uneven rolling resistance from tyres (uneven inflation, badly mis-matched brands / types)
Brakes binding.
Chassis damage - the car itself being "twisted".

Simple tracking (ie: front toe) will cause reduced stability, heavy steering and extreme tyre wear - which may lead to a pull over time thanks to the effect on the tyre's performance but - provided there is total toe-in (which assists self centering) - it won't directly cause the car to steer either way because it will centre itself when moving

AdrianC

Joe_Horner wrote: »

Rear toe is different because the only way that can "correct" itself is by the whole car turning.

Which, of course, still evens out, with the steering being held off-centre to compensate - just with the car crabbing slightly.