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2007 C6 Z06 with LG coilovers with 600# springs running Hoosier A7s 315/30/18s in southern California tracks showing heavy shoulder wear with good tread everywhere else. 3.0 negative camber front, 1.5 degrees neg camber rear, 0" toe. Run 25# cold and 32# to 34# at the end of 20 minute sessions. .Tires are cording on the shoulders despite more tread left on the wear bars. Any ideas why the wear is so pronounced? I flip the tires to get more sessions but the shoulders wear very quickly!
I have had 3 customers experience increased tire wear on the outside shoulders running A7's - I would say that it started in happen around tires dated mid-late 2017. Nothing has changed on the set-ups of the cars but not only fronts but rears are wearing out the shoulder quicker than usual. I emailed Hoosier and got the response that I figured I would get - that we are running our pressures too low and that's the cause. If that's the cause why didn't we have this problem previously?
I've set up cars running A6/A7's for over a decade and have never had this issue - it's a tire issue - but Hoosier isn't admitting they have a problem - I was told that they have been receiving more complaints than usual from Corvette owners about outside shoulder wear!?! So you're getting more complaints than usual but there isn't a problem!?!
I asked if there has been a change to the compound or construction and was told nothing has changed in compound or design since the A6 was introduced - if nothing has changed and people are complaining then something doesn't add up.
Here is an example of what we are experiencing
This is a picture of a tire I received from Phoenix performance - this tire had 2 or 3 sessions on it
If you look at the outside shoulder there is a noticeable step were the outside shoulder is worn much more than the rest of the tire
Same tire top view:
Now here is an A6 that I had laying around that also had 3 sessions on it:
Again top view of the A6
These are examples of the differences that I have seen in Hoosier A's since late 2017 - there is an issue - not sure if they know this and are fixing the issue or what.
I did talk to another race buddy and he said that guys in his class switched over to R7's because the A7's wore out too quickly - and have been happy with the switch.
add more front camber. i was able to get -3.3 and not even maxed out with all stock parts. (09 C6Z) i think we could have got to -3.5 by playing with caster and toe.
remove all your upper A arm shims, and max out the cam bolt on the lower A arm
also try increasing your pressures. both will help.
What conditions are your bushings in, and are they stock? The stock bushings are known to flex considerably with even a decent street tire like a PSS. You have much more grip than that, which would create even more pressure on the bushings to flex. This could easily take your -3* of static camber to an unfavourable amount (less negative) of dynamic camber.
This is not a set-up issue, the cars that I set-up have won multiple NASA Championships - and up until late last year we were getting great wear on A6's & A7's - nice and even across for the life of the tire.
Of the three cars that I set-up who run Hoosiers one is on poly bushings, one is on delrin and the last one has a set of custom upper A-arms that are set to -3.7° front camber and -2° rear, still cording the outside 1". These are cars that have been sorted and wore tires evenly for years - then late in 2017 all three of them have the same issue?
It's a tire issue - one that hopefully Hoosier has figured out or we'll be switching to R7's next year.
Last edited by 96CollectorSport; 07-30-2019 at 10:52 AM.
Thanks for the replies. My tires look exactly like the ones shown by 96 CollectorSport. I have Pfadt alignment shims and Delrin bushings and T1 sway bars. R6s always wore evenly but switched to A6s for more grip. How do R7s wear? Thanks again.
100% Not a setup issue. Hoosiers this year wore much faster in both my C6 and Miata race cars. Going to run R7’s for practice ans A7’s for qualifying and races.
Those of you seeing early excessive shoulder wear, are you taking a torch and putty knife removing track pickup and seeing the center molding stripe down the middle still intact?
Bringing this back up to see what people are seeing this year. I'm still noticing excessive shoulder wear. I know there are many factors but if all set ups are showing the same then to me it would seem to be a tire issue.
I am still finding the A7's wear the outside edge very quickly, especially in very hot conditions (my last 3 races were in 90f+). I am now flipping them after 2-3 heat cycles to get more life out of them. The R7's are not wearing as fast but are slower by about 1 sec from the A7's but they not only have a longer life span they also hold up better in later laps in those hot conditions. I also started experimenting with pressures and found around 33 hot to be the ideal spot between speed and life span. But that changes based on ambient temp, track, weight, etc. Hoosier wants me to be closer to 40, yet to try that. Any other updates or info?
Checking to see how this year is working out for those still running Hoosiers. I am still experiencing quick wear and cording. Been getting more life by flipping them, but 6 to 6 heat cycles tops is what I get. Hoosier's recommendation is to run 40-42 hot pressure based on my set-up?!?! They literally said "it will slide around and feel loose but you need to learn to drive the car that way".
so although you have already answered the question.....you guys are seeing what is common an expected in these tires.
Most all tires I've run in the last 25 years will show best efficiency/wear in the 38-39psi HOT range. You pyrometer will help you dial in the correct camber, but the pressure needs to be in this range. That is what Hoosier recommends, and they are correct.
However, maximum performance and maximum wear are completely different animals. Yes you will go faster running low pressures...ideally with more aggressive camber. But, they tire is rolling over on itself and committing suicide.
This is great for Time Trial, or qualifying where only a lap or two counts. If you are running 25psi cold/32psi hot on tires as sticky as an A7, you absolutely shouldn't be running them for 25-30min DE or 60min race sessions. It's in AUTOCROSS tire after all.
So you get to choose, do you want maximum short term performance, or do you want maximum life.....?
so although you have already answered the question.....you guys are seeing what is common an expected in these tires.
Most all tires I've run in the last 25 years will show best efficiency/wear in the 38-39psi HOT range. You pyrometer will help you dial in the correct camber, but the pressure needs to be in this range. That is what Hoosier recommends, and they are correct.
However, maximum performance and maximum wear are completely different animals. Yes you will go faster running low pressures...ideally with more aggressive camber. But, they tire is rolling over on itself and committing suicide.
This is great for Time Trial, or qualifying where only a lap or two counts. If you are running 25psi cold/32psi hot on tires as sticky as an A7, you absolutely shouldn't be running them for 25-30min DE or 60min race sessions. It's in AUTOCROSS tire after all.
So you get to choose, do you want maximum short term performance, or do you want maximum life.....?
We should really let the guys over at G-speed know that they shouldn't be running the A7's for a 35 minute race - even if that's the tire they ran to win ST2 at NASA Nationals last year.
11-20-2018, 11:06 PM
Excessive tire shoulder wear
