All.

Let me try to summarize this in a 'short' post..

Purchased a set of 16" Direzza tires with GramLight wheels back in april of 2009 from Alex @ TireRack. I ran 3-4 club AutoCross events over the spring/summer/fall and noticed that after one of the last events in October that my front driver and passenger side tires were starting to peal (again.. after 3-4 events and a total of 3100 driving miles). Alex and Dunlop were able to credit me for (2) new tires and I replaced them back in November where I ran one more AutoCross event before the Mini went into hibernation for the winter.

Fast forward to this past weekend for the 1st AutoCross event of the year. We got about 10 runs in on a 1.4 mile course and noticed that the pealing issue was happening again but this time only on my front drivers side tire (this time.. 2 AutoCross events and under 2000 driving miles on the tires). After the 1st time I chalked it up as possibly a defective tire but since this is happening again I'm not sure what the heck the problem is. I had a performance cross weight / center balance alignment done 2 weeks ago and have attached those results as well as some pics of the tire that I took yesterday afternoon. Tire pressure when cold was around 37psi and after a run was around 44-46psi. Air temperature was around 70-75F and the course is a old military airfield which is in good shape. There is no visable tire rubbing or anything like that.

Thanks for any guidance! Jeremy

 

I am no suspension pro -- but your camber settings look low to me -- I would suggest 1.5 to 2.0 front camber. Your BC coilovers have adjustable camber plates correct?

With the added camber you would not roll the outside edge as much where you are getting the peeling.

Would appreciate a suspension pro's confirmation please.

 

Such are the nature of tires. Every set of Dunlop Direzza Z1 star specs (and Bridgestones RE11 and Yokos Advans) I have run on the track had done this. In track lingo, it is called chunking and heat cycles and depth of thread are the main culprits.

The best thing to do is to shave them down before running them at the track or autox. Start with about 4-5/32" depth. Or just run them on the street till they are at that depth before going off to the racers. This way you reduce tire squirm.

You may need a touch more tire pressure as well. A little more camber like Ron has suggested would be good as well.

 

thanks guys. I heard the same thing with the Z1 Star Specs about being the nature of the beast but hadn't read about shaving them down. I'll rotate theis tire to the back in order to get fresh tread up front for the next event in May. I'll contact the alignment guy about getting alittle more camber adjustments as well. I believe he said he didn't have much to work with from a coilover standpoint without taking some metal out from around the strut tower under the hood so I'll see what it will take to get that fixed.

 

That looks like it might be typical tire wear pattern of a macpherson Strut Suspension with insufficient camber for the usage and a possibly rough, grainy "road" surface seen in parking lots.

Which model Dunlop is that?

One way to address the wear issue is to increase negative camber as Ron pointed out. That should help spread the wear surface to the rest of the tire's tread instead of just the corner.

 

+ 1 I agree, see this hundreds of times

 

As far as I know, all the extreme performance tires have this problem.

Go driving and wear down the tire. If you put the back ones up front, they will chunk too if they have too much thread depth.

You are getting tire folding as well. There is a little triangle arrow that should be the max wear point when you are cornering (see picture 3 above the end of the word temperature). And you are way below that. So a little camber and tire pressure would help.

If you want to go to -1.5 to -2.0 front camber, you will need front camber plates.

 

This post shows how to cut out for the BC Coils for front camber-- You will see the pictures of the dremel tool cutting the need adjustment room.

https://www.northamericanmotoring.co...-feedback.html

 

+1 ron-s mini and slinger688
I have a fresh set of unshaved Nitto NT01s that slightly chunked increased from 32 cold to 35 cold and it held much better.

 

Howsoon,

Did you heat cycle (treat) the NT01s before running track?

 

Nope
Mounted and pulled stickers off tires and did Laguna Seca.

 

Thanks, I think I will heat cycle mine and wear them down a little on driving around before heading out to the track.

 

A Heat cycle , a good scrub in, and rotation between sessions!

 

As many have said, you need more negative camber in the front. It would also be good to reduce the amount of negative camber in the rear. I think it would be worth the effort to modify the front strut towers (post #8) so you can adjust the front camber into the -2 degree range.

It looks like you have a small amount of toe-out in the front, which I think is good. I would reduce the toe-in at the rear to closer to zero.

 

Keep in mind that cutting the strut tower will put you from Street Prepared to Prepared class. Have your installer try a ball end wrench, he may have enough room. I used these on my Cross coilovers:
http://www.sears.com/shc/s/p_10153_1...6384000P?mv=rr

 

I think he is talking about cutting the rear trim for the rear coilover to get access to the adjustment mechanism.

The front strut tower looks OK for access.

 

thanks all. I have a appointment scheduled for tuesday to get the camber adjusted to -2. Because he couldn't see the camber adjustments he is not charging me to re-align the car which is really nice. He will also be installing new MM Front Control Arm Bushings so hopefully we should be good after this. Thanks again!