MIP

Ah crap, not good. I've been noticing some vibration over the last few days. Got the wheels balanced yesterday and no change. Was quite signifigant on the motorway. More so as I dropped to 70. And not just through the wheel, through the seat, felt like the whole car juddering.

I've been having a look at it in the garage this eve, and noticed something very signifigant. Took the rear wheels off to start with and this is what I could see...

Rear right:




Rear left:




As you can see, the rear left is signifigantly worn down and will need replacing. There's also a thin rib of rubber along the center (with small evenly spaced kinks in it). When I was doing the brakes, my friend did notice that the wear was uneven, but I hadn't looked closely with them side by side and realized how serious the problem was.

Last time I saw somthing like this was on my friends MR2 when one of his brakes where binding. So that's what I've looked at first. I could turn both wheels by hand ok, so instead, with the car on stands, I tried it running in first gear and both wheels turned evenly at first, but eventually the left did stop and all power was going to the right, so... maybe. What I've done on both rear calipers is taken the sliding pins out, cleaned and re-greased them, and check it slides smoothly (or is it the actual piston that seizes in the caliper with this type of problem?). I've swapped left and right and gone for a drive down the bypass, and no juddering this time, so maybe I've got it.

I hope I've got it figured out, but I'm all ears to any other suggestions. I'll have to get new very rubber soon, but I need to be reasonably sure I'm not going to rapidly destroy the replacment tyre.

Does the thin line of rubber down the center of the worn tyre indicate anything in particular or is that just how it wears?

unclefester

I always thought centre tyre wear was down to over inflation and outer shoulder wear was down to under inflation.

Except that a tyre that is warmer will tend to run a higher pressure so you have to work out what is causing one to get hotter than the other.

Generally you can go for a run, coast to a stop, get out and feel the tyre temperature, one part of the tyre should not be significantly hotter than the other.

I can't see how brakes binding would do that without showing some signs on the brakes as welll as the tyre?

Thinking on from that, if the geometry was out on that side, t hat could cause the tyre to heat up which could explain why the centre of the tyre has worn - from what I understand of suspension, there is no way geo being out could cause centre wear on its own - you'd either wear out one or other shoulders, the tyre at an angle or the entire surface of the tyre.

MIP

I'm not sure. I'd say the wear is fairy even apart from the little lip in the middle. I do check that the tyres are 32psi all round every other week as well. But even if it was just inflation, I wouldn't expect such a huge difference between right and left, there's probably 5-6mm on the good tyre and maybe 3mm on the f00ked one.

edit:



I should mention! It's new disks and pads last week, so may not be able to see much sign of the issue on the brakes, if brakes are the problem. But the tyre wear problem was there before changing the brakes, just hadn't realized how serious the problem was (and no noticable juddering had occured at that point).

loftust

Pressures, brakes, geo...in that order

unclefester

The only thing I can think of in that case is geo settings, when were they last checked?

MIP

Geo was done at WIM less than a year ago (5-6 months maybe? 4500 miles ago). I'm convinced pressures are ok, I do check them frequently. So brakes it is probably, unless the geo's been knocked out signifigantly on one wheel. I havn't noticed any dodgy handling.

Also, that rib of rubber may or may not be part of the stucture of the tyre as it wears low it gets exposed maybe? I don't know.

I'll go back to WIM for the new tyres, get Tony to check it's aligned still at the same time, see if he's gone any further idea's on the cause (I've put this post up on his forum as well).

MIP

Tony tells me that kind of wear pattern is normal for the tyre, so I'm not going to worry about the little lip.

razzele

You can expect the left tyres to wear more than the rights if you drive hard.

Roundabouts are right handers and if you go to the track most corners are right handers (clockwise circuits).

punchdrunk

I'd go with the geo settings. Binding calipers stink of burning rubber, you'd be able to tell - the car would also feel lethargic.

If the tyres were bought at the same time it's obvious from the wear that one side has better contact patch than the other.

MIP

I'm guilty of taking a few round abouts on the way home rather enthusiasticly. I'm suprised it would result in that much difference between the two, but perhaps you're right and it's just down to me then? I'm going to need to learn some restraint.

I'm not clear on why I got the occasional shuddering/vibration even after getting the wheels balanced though. I'll see how it behaves now with the wheels swapped sides on my journey down the M4 after work...

Or maybe just the toe has been knocked out on that side.

Should I get both replaced as a pair, or just the one that's badly worn? (I'll have the rear geo checked at the same time).