Z4MC - frustrating Cup tyre wear

[sixspeed]

Just back from a tour around Europe. Did around 3000 miles, and had a trackday at Imola and a few laps of the Ring whilst out there. By and large, it was mostly road miles.

I put a fresh set of Cups on the car a couple months before I left. Probably did about 750 miles on them before we left.

So this is the state of the tyres now having returned to the UK.

Main Body of Tyre


Inner wear




As you can see, the bulk of the tread is in a good state, but there is a band around the inside that has worn excessively. This is the same on both sides. This happened with the last set too, and I had the alignment checked and reset when they were put on, and nothing was wildly out. Setup on the front is currently -2deg of camber, and 0.2mm toe in. Previously it was set to -2.5deg camber, and 0.5mm toe in - but I backed the settings off a little thinking they may have caused the issues last time. But I'm not convinced these are particularly aggressive, and don't think they are the cause?

Any ideas?? To me it looks like toe, but 0.2mm shouldn't cause this level of wear, should it? I'm wondering if there are some faulty/worn bushes, although I'd expect to have noticed this when driving the car (there was some tramlining on motorways, but I've put this down to ruts on the road and the stiff sidewalls). At a bit of a loss with it really, and can't justify burning through Cups at this rate so any advice welcomed!

Edited by sixspeed on Monday 22 June 20:48

[Top pup]

That simply looks like to much camber for that tyre in that application, rather than anything else.

[mark.c]

Looks like too much toe. I ran an M3 with just over 3 deg -ve camber and a small amount of toe and it did exactly the same. A couple of sets of front tyres later I tried with the fronts set parallel and it reduced the wear significantly to almost nothing. It in no way compromised how the car felt either, improved it if anything.

[Kawasicki]

toe wear.

[AW10]

Seems like a lot of negative camber for road use?

[GregorFuk]

Great. So we've narrowed it down to too much toe or camber

[Cheburator mk2]

From memory when I still had my Z4MC, standard camber setting is 1deg 15min, so you are almost double that... The way you are wearing the fronts I think you don't have enough toe in for a bit more even scrub of the contact patch. Your current setting is great as it removes the in-built understeer of the standard car, but there is a small price to pay. I suffered exactly the same wear problems with Cup+ - went back to standard once the car was retired from Ring duties and wear became even.

[sixspeed]

The car is mostly used as a track toy, but does some occasional weekend drives, and of course the drives to/from the track (wherever that may be - in this case, Italy!)

I ran road (PS2/PSS) tyres for quite some time but as my mileage has fallen and the ratio of track driving has increased, I decided to run Cups. Obviously it looks like these are no good, at least with this geo setup, for the amount of road use the car still gets.

I'll get the car checked over anyway, but looks like I might have to consider going back to a road tyre. Having a separate set of wheels/tyres isn't really an option as transporting them would be nigh on impossible.

Edited by sixspeed on Tuesday 23 June 13:10

[Galahad]

Is it better on track with less aggressive geo and cups, or the current geo and road tyres?

[nickfrog]

Are these original Cups not Cup 2 ? I understand the Cup 2 wear better but I would also go down to 1.5 deg of camber and less toe, worth a try.

[AW10]

sixspeed said:

The car is mostly used as a track toy, but does some occasional weekend drives, and of course the drives to/from the track (wherever that may be - in this case, Italy!)

I think that's the problem - far too many road miles with high neg camber of soft tyres. You must have done 2000+ road miles to get to Imola and back?

[sixspeed]

Is 2 degrees (over a factory setting of 1 degree) really that much extra to cause that kind of wear? Bearing in mind that the M3 CSL runs 1 degree 45 mins (so 1 3/4 degrees) also and afaik doesn't suffer this issue running Cups on the road in standard trim?

I'm not convinced tbh.

The more reading I do, the type of wear seems more attributable to toe. However, that was set nigh-on neutral (0.2mm or 0 deg 1' toe-in). Which leaves me with one of three outcomes in my mind:

- it was set incorrectly
- it was knocked out at some point (kerbs on track?)
- there are worn bushes/suspension components causing play


Car goes in on Monday, so will report back with any findings then...
.

[mark.c]

It is definitely the toe, whether it wasn't set right or got knocked out is anyone's guess but you can run that amount of neg camber and parallel toe with negligible wear. I did exactly that for two years and many thousands of miles.

[AW10]

Any update?

[adriman]

Wouldn't too much toe in cause wear on the outside shoulder? Would point to the Camber right?