Tyre wear

[Lancerlot]

Paul, As the wear appears to fairly even each side, the most obvious cause is too much rear negative camber. You do not say how many miles you have covered, but the springs tend to settle with use and this lowers the suspension, producing excessive neg. and an uneven contact patch on the tyre. Excessive wear on one side would likely indicate an alignment defect . Chris Franklin at Center Gravity will check out all the components prior to carrying out alignment so you should be OK after your visit. Regards, Clive

 

[paulmichele]

Cheers Clive. The car has done 75k. Though I don't know how long this set of tyres has been on the car. It does seem odd that both rear tyres that have worn most on the inside shoulder; and both to a similar degree ... which made the tyre fitter think that it was not an alignment issue (but he didn't claim to be an expert).

 

[paulmichele]

Bad news at the weekend, my car failed its MoT. [] According to the test station, there was "ply or cord" showing and therefore a straight fail.

The near side rear tyre had worn very badly right on the inside shoulder (and the offside had worn similarly but just to the legal limit). I've driven the car pretty normally, I think - nothing more than a couple of "track" days (Porsche Experience and an IAM handling course, rather than anything close to a tyre-burning blast) but nothing else. The fitter wondered (as a guess, rather than from knowledge) that it could be the camber??

I hope the picture gives you some idea (but if it doesn't work, then the words are that the tyres are worn fairly evenly across the width but with 2-3mm of tread still in most places).

On inspection and reflection, and after a £600 bill for replacement tyres (big thumbs up to blackcircles.com), I'm left wondering how the tyres had worn in this way? And whether there is anything I can do to prevent it happening again (I couldn't see the wear at all, hence the shock of failure).

Your thoughts very welcome (I am expecting you all to recommend a trip to Center Gravity, of course; but I'd like some knowledge ahead of that).

Thanks.

 

[Lancerlot]

Paul, With that mileage, I would expect the suspension to have settled quite a bit. The inside shoulders wear because this is the section of the tyre that is most in contact with the road surface. I hope the diagram below shows you what I mean.

Regards, Clive.

 

[kasspa]

Paul, I'd get that alignment checked asap before you start to wear those new tyres in the same way...... I would assume that there is no component wear issues or this would have been raised at MOT too!

 

[RJKflyer]

I've started to track my tyre (and pad) wear on a simple spreadsheet which alarms if it spots uneven wear. Just an idea...

 

[garyw]

Every one of my rear tyres has ended in a very similar way [] It is how the car is setup and Chris did remove a bit in order to allow a bit better wear rate on the rears.... unfortunately the better grip has caused me to enjoy it that bit more and get the same wear anyhow [:'(] [] I usually get about 10-12K from a set of rears.. the last set had 2.5mm in the centre and cords on the very inside edge. garyw

 

[paulmichele]

Thanks Gary (and all)

Every one of my rear tyres has ended in a very similar way

So if a tyre starts with 8mm of tread and lasts 12,000 miles (down to 2mm), and a pair costs £600, then each 1mm of wear costs £100 and gives 2,000 miles of driving. If I continue with the uneven wear then I risk replacing the tyres with 3mm left (instead of 2mm). This will therefore "cost" me another £100 in wasted rubber and mean replacement after 10,000 miles. Or I could spend £300 on alignment and assessment.... which on a £ basis will cost me. But then again, I get the benefit of knowing that the car is set up correctly and the natural ageing will have been sorted.

 

[tscaptain]

On all of my visits to CG Chris has reduced the amount of neg camber on the rears (final reading -1deg35mins). As has been highlighted by Clive this increases the contact patch in a straight line and reduces, but does not eliminate, the wear on the very inner edge. (It also reduces understeer) Of course the idea of neg camber is that when cornering the outer wheels becomes a little more "upright" and improve grip further. I got just over 12k out of the rears too but at £100 per 2000 miles of driving it's a lot cheaper than the fuel!![] I think Chris recommends a realignment around every 20k miles after the initial settling of the suspension.

 

[Schleicher]

Corded the right rear on my GT3 in similar fashion. That was running at -ve 1-34 (per Chris at CG). Lasted about 10,000 miles, tyre depth measured 2.1 1.7 1.7 across the width. Robert