Tyre not running true

[Space cat]

Our W-reg Renault Scenic (1.6 petrol) is due its MOT soon so I did a quick tyre inspection and found that there was a small piece of rubber missing from the nearside front sidewall. Although no cords were exposed, I decided to put the spare on instead - and that's when the wobble appeared in the steering. So I jacked up the wheel, rigged up a rough and ready pointer alongside it and established that the wheel rim runs true but the tyre doesn't. It swings in and out by quite a few millimetres.

What I'm not sure about is how this happened because it's not a new tyre. Long ago I would have bought one new tyre, fitted it opposite the new spare and put the best old one in the boot. I've now moved it to the back and the wobble has gone but what I'd like to know is:

1) Do you sometimes get tyres that don't run true?

2) Can a tyre develop a wobble over time?

2) Is it safe?

3) Will it fail the MOT anyway?

Thanks in advance for any answers.

 

[Burnerman]

I think the tyre has a damaged sidewall, presumably with an internal bulge where failure has occurred.
The MOT has a visual inspection of the tyres and if there's any obvious bulges or damage on the side then it will fail......but they won't generally check for runout. However, the alarm bells could ring when the car is on the brake roller machine and the tester would then look further. Maybe your spare has been run flat at sometime? Either way, its not a good idea to be using it!
John

 

[Avocet]

Does the wobble vary gradually as the wheel goes round or is the tyre true for "most" of each revolution and then just "kicks" slightly in one place? If it's the former, you might be able to get a tyre place to take it off and re-fit it. If it's the latter, I'd agree with Burnerman, there's probably a fault in the sidewall - potentially very dangerous.

 

[Space cat]

Thanks for the replies so far.

I think the tyre has a damaged sidewall, presumably with an internal bulge where failure has occurred.

I did look for sidewall bulges and found none but of course I couldn't see inside the tyre.

Does the wobble vary gradually as the wheel goes round or is the tyre true for "most" of each revolution and then just "kicks" slightly in one place?

It's true about two thirds of the way round then the remaining third drifts slowly out and in again. The total displacement was hard to judge but I think it might have been up to 3mm. If I look carefully I can see the distortion in the tread itself. The circumferential grooves have slight sideways bends in them.

I was reluctant to replace a tyre with almost 3mm of tread on an old car that doesn't do many miles these days but, having read your replies, I think it's time to bite the bullet and get two new ones: one for Mr Wobbly and another for the spare with its missing piece of rubber. I'll put them both on the front, the best of the remaining three on the back and the last one in the boot.

 

[tebreak]

You say it's an old car with low milage per year? It may be am idea to check the age of the other tyres. They should be changed if over 6 years old regardless of how good they appear to be.

 

[Arthur2shedsJackson]

I worked in a tyre bay some years ago and this problem presented itself.
Turned out that water had got into the tyre and the constant swishing about had caused it to run out of line.

However, at 3mm there isn't a great deal of life left in it anyway. Why don't you look for good secondhand one or a pair if you're reluctant to spend on the car?

 

[Space cat]

Well, the deed is done (no, not in the mumsnet sense ). I got two new tyres for £72 each from a well known supplier starting with the letter "K". I asked the fitter whether there was any visible damage inside the wobbly tyre but he said not - and I'm sure he would have told me if it was full of water! I told him about the wobble but all he could suggest was that it had needed balancing. I couldn't see how that could really explain things but I guess it'll remain a mystery now. Thanks for the replies.