Dziner82

have you guys seen wear like this?

i have done 1 track day and about 12 autocross events on these tires over 8 months, including a 4 month break int he winter. its only the driver side front tire that looks like this as i make many more rights than left turns at the events. the passenger side front is not separating and is wearing more evenly. there is only about 3500 miles on these tires, maybe less if i check my records, at least half of those miles are highway driving to the events.

many other drivers at autocross are running street tires and not having this issue with many many more miles and wear on their tires.

these are Cooper Zeon RS3-S tires. supposed to be their highest performance tires. Developed for OEM application for the Roush mustang. "track tested" they claimed.

discount tire is claiming that they are just not meant for the type of use i had them in and that the temps got too high.
while i agree with that in principle i dont see many people having this problem with their 300 treadwear street tires at track days or autocross events.

do you think i have a legitimate argument with cooper tires here?

Dziner82

another note...
after my track day a month ago i had about 4-5 of these tears-separation areas on the shoulder tread. then 2 weeks later ran another autocross and maybe had 1-2 more. then after autocross today the entire shoulder is torn and separated.

I have the 2nd day of the autocross tomorrow and a track day on monday so i had to get some replacement fronts of whatever the local place had in stock. Falken 612 model is what they put on the front to cover me for a couple weeks until i upgrade to a better set all around.

Saaboteur

Have you checked tire pressures and alignment lately? That looks like quite abnormal wear.

Dziner82

alignment was done about a month ago when i put the new shocks on.

tire pressure i run during autocross is about 40psi. which is the pressure i have found works best to keep the tire from rolling over the sidewall, and wearing at the markers on the shoulders as it should. i check my tire pressure very often to make sure it doesnt get too high or too low and always return the tires to everyday driving pressures after the events.

the damage started on the shoulder like that after the 1 track day i did. i ran six twenty minute sessions, which was about 8 laps per session, 7 hot laps and 1 cool down lap. about 45 minute break between each session.
i was running around 38-40psi that day at the track in the fronts. so by the end of the day it was about 50 laps, and each lap had about 7 right hand turns and only about 1 left.
initially there was about 4-5 of these gouges in various spots around the tire. then next autocross it stayed the same, then this last autocross the whole tire went to hell. today was pretty high heat to, probably 90 degrees on the driving surface.

in high speed turns or even low speed hard turns the car really leans on the outside edge of the tire. i plan to get a camber kit but i was just really surprised on how quickly this tire got destroyed.

which is why i feel like its more a failure on the tire vs something not right on the car.

dls55amg

my guess would be toe and or camber

Dziner82

i will post my alignment specs soon, i have them from the shop when it was done. i remember they said they set them "as close to factory settings as possible" i think one of the 3 settings were not within the stock range.

Ausmbtech

I've seen wear like that before. You're either running very little toe in or some toe out (unlikely if only 1 tyre is doing it) or you may have a tyre belt seperation issue. I had 3 sets of Pirelli's do it on a C43 and a E55. I managed to catch a tyre doing it very early on, the 2 pics are of the same tyre on the same side, it had only seperated 1/2 way round the tyre at this point. I had 5 tyres in total with this damage and they still wouldn't accept it was a faulty product.

Id just buy another tyre and recheck the alignment, it's not worth the never ending arguement over road damage, tyre pressure, kerb damage, etc etc.

dls55amg

its very rare that tire dealers ,manufacturers take what we call in the tire industry as adjustment,or a defective tire, separation, broken belt,out of round ,bead damage,99%of the time they claim its mechanical r u using z rated tires,running compressed air or nitrogen,i recently acquired a 98 c43 amg mb recommends 36 psi front and 41 psi rear for summer air pressure tho im guessing on the track your car requires diff pressures,for me 41 psi for rear was to harsh of a ride however acceleration was better,now im at 35 psi rear due to a right rear suspension issues,can anyone recommend what brand front upper control arms to use on the c43?

Dziner82

yea discount tire claimed it was just too much heat into the tire from me using them for something "they weren't meant for".

im more disapointed with cooper, as many other drivers are using street tires and getting better wear/durability than this.

I replaced the fronts with Falken 612's since that was one of my few options in the time crunch that i was in. After running the 2nd day of the autocross on them i can tell the falkens have better sidewall rigidity than the coopers did.
im doing a track day tomorrow, i will try to somewhat take it easy so that i dont destroy these fronts as well but it will be a good gauge on if they are more durable than the cooper zeon's.

I will look into the camber specs and adjustments this week. from what i researched on here already im understanding that our cars only have very minimal camber adjustment capabilities? is this true?
We can get eccentric bolts to get slightly more adjustability? but need the KMAC setup to get full adjustability?

m a x i m u s

I ran Michelin pilot AS on my C63 and had similar, if not worse, chunking issues. Switched to a higher rated tire and didn't have the same problems.

Sulaco

My front right wears similarly on my C43. No idea why, but I've done squat about the camber or alignment on it, too.

dls55amg

I assumed that would be there response,not to agree with them but they have a small point,ive heard and seen some guys using polyurethane bushings in control arms and sway bars with the z rated tires to keep tire roll to a minimum,these bushings have a durometor of 95 or 95% ive delt and serviced industrial tires having the same durometor,a reference would b a brick or cinder block having a durometor of 100,no give flex at all ,my next project is upper control arms,left side is shot,my guess is yes not much of a camber adj which makes sense our c43 s should have z rated tires and stiff sidewalls ,after I decide on a brand of control arm im leaning towards the falkens

Dziner82

what sway bard do you know of people using? from what i have read there isnt really any aftermarket bars that are improvements over stock, id be happy to hear that there is!

also, the all season 'run of the mill' falken tires i can already tell are stiffer in the sidewall and holding up better than the coopers did. might have to do with load rating of the tires which i hadnt really looked at in the past.

I would have completely agreed with the guys at the tire shops had i not seen people go harder on tires that are supposedly "lesser performance" than mine and not have failure like i had. but again they did bring up the load rating at the shop, that may be the key for a car like ours that leans so much on the relatively skinny front tires.

Ausmbtech

That wear pattern isn't a camber issue (unless you have 5deg or more neg camber). If it was a camber issue it would have a angled wear across the whole tyre, not just in a localised point.
Kmac bushes change the amount you can move the lower control arm from 3mm +/- to 6mm +/- which is about .75 of a degree in real terms. More neg camber wont hurt but it wont solve that issue.

Dziner82

i agree.
to me the camber is just to get the car to handle better since this front left tire takes so much of the load in the right hand turns. this tire failed prematurely under load and heat in my opinion. a better tire would not have.

with that said, the car still needs a bit more negative camber to handle better and let more of the tire patch be in contact with the ground under hard cornering vs rolling to the outer edge as it is now. when i have better tires they will still wear prematurely on the outer edge due to the amount of lean/roll and abundance of right hand turns, hopefully less with more neg camber.

Dziner82

so here are the alignment specs from the shock install about 6 weeks ago. hopefully im translating these correctly:

Front left:
camber: -0.8 (spec range -0.8/-0.2)
caster: 4.5
Toe: 0.24 (spec Range 0.12/0.29)
SAI: 12.2
Included angle: 11.5

Front Right:
camber: -0.8
caster: 4.3
Toe :0.22
SAI: 18.7
Included angle: 18.0

do you guys know how far negative we can go on camber on the stock mounting bolts?

benzslo

cooper tires are a low quality tire. those pictures don't surprise me being a cooper tire.

how far you can get with the bolts depends where you're starting from. i can tell you the adjustment bolts generally get you another .3 degrees one way or the other depending on which way they are installed, compared to the stock bolts in middle location.

your front toe could also be closer to zero, but it's not responsible for that wear..

i do alignments at my dealer. i'd recommend talking to the guy doing your alignment, he'll understand what you're going after and work with you.

Dziner82

yea as far as the coopers i saw they launched these as their first true high performance tire, and the comparison tests looked pretty good with its competition, and they developed it with the roush mustang, etc, etc, so i bought into it.

i posted the photo on their FB page, and they did respond asking for my contact info, but i have not been contacted by them as of yet.

I will talk with the guys at the shop and see what we can do with adjustment bolts on the camber. anything additional i can get in the front will help, i will try that first before investing in the KMAC.