When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Just noticed some unusual chunking/peeling (delaminating?) on the inside of the passenger front tire. In a few spots the cord is visible. I've never seen wear like this before on this exact tire. Car was just aligned to the OEM "track/competitive driving" spec right after these were installed (see below). Everything is stock and there's only a few thousand street miles on them.
Driver front tire is not doing this. Rears are fine.
Tire Rack looked at the photos and said it's either something off in the alignment, or it could be a product of the track/driver inputs. They're claiming it isn't a defect.
Any ideas what's happening here? Should I have the dealer re-check the alignment? If this is considered normal, I'm pretty pissed -- that means the track alignment has done nothing to extend tire life up front. My original MPSS on the OEM alignment lasted the exact same number of track days.
He said a few thousand street miles, sonprobably no track miles.
A more aggressive alignment will even tire wear when it is driven more aggressively. Otherwise, more toe and camber will wear the inside more.
And i would hypothesize that you have taken a few right-hand on-ramps pretty fast to help wear out the inside of the right front quicker than the left.
He said a few thousand street miles, sonprobably no track miles.
A more aggressive alignment will even tire wear when it is driven more aggressively. Otherwise, more toe and camber will wear the inside more.
And i would hypothesize that you have taken a few right-hand on-ramps pretty fast to help wear out the inside of the right front quicker than the left.
Originally Posted by Dirk Miller
Just wondering how many sessions and in what run group have these tires seen?
Thanks
8 track hours. I just find it hard to believe that a few tenths more negative camber that it had before destroyed the tire this fast. My first set of MPSS lasted just as long (8 hours) but with the previous alignment spec you see there.
Originally Posted by davidfarmer
front toe seems excessive to me, and isn't helping at all on the street. Camber isn't that high, unless it has moved.
0.04 toe in is well within the spec and I would not call that aggressive at all.
front toe seems excessive to me, and isn't helping at all on the street. Camber isn't that high, unless it has moved.
But it is toe in Vs toe out and shouldn't cause that kind of wear on the inside of the tire. It also seems like if it was a toe problem it would affect both tires as the steering would turn to make toe equal on each side when moving. At -1.6 the camber setting isn't excessive. I have -2.3 camber on my C7 Z06 with some toe in and I am not getting that kind of inside wear on the street. The LCA cams may have slipped on that side and his camber/caster/toe could be way off but that should also show up in the steering wheel angle as the steering turns to equalize toe.
First thing that should be done is to check the alignment to see if something has slipped.
OP. If you happen to have a 2 ft long digital read out level at home you can check the camber very quickly yourself. First decide where you are going to park the car and then use the level to measure the ground angle cross wise of the car at the point the front wheels will be located. Then move the car into position with the steering straight and place the level vertically on the right front tire ahead of or behind the tire bulge where it sits on the floor. Make sure the level isn't on the floor. The camber of the wheel is the difference between the two measurements. If the car is leaning to the left then subtract the floor angle from the reading on the tire and if the car is leaning right add the floor angle to the reading on the tire. That will give you the amount of camber in the right front. You can also check the other wheels the same way. For a quick in the ball park check this is sufficient to give you an idea of what is happening without running to the dealer.
Bill
Last edited by Bill Dearborn; 07-19-2018 at 12:01 PM.
We don't often look at caster angles as an indicator for tire wear, but it does indirectly affect other alignment specs.
Strictly speaking, caster is not a tire-wearing angle. However, the more positive caster a vehicle has, the more its tires lean over during turns.
In other words, increasing positive caster increases camber change during turns. Camber change on turns is sometimes called camber roll.
Some vehicles are designed with extraordinary positive caster-sometimes twice the normal amount. When such a vehicle is driven mostly in the city, it experiences frequent camber roll because a city vehicle turns lots of corners. Consequently, its tires may develop a shoulder-scuffing pattern associated with camber wear.
This is commonly seen on BMW M cars up front, my MZ4 Coupe doesn't have as extreme of a wear pattern but at 5.5-6º it's considered to have a TON of caster compared to typical cars. I can see the inside edge is flatter than the outside edge despite a decent amount of toe-in. At 8º of caster in the front on your alignment, I suspect the effect it has of increasing camber roll as the tires are driven on the street to be MAGNIFIED?
It’s hard to read the specs but they don’t sound extreme.
But 8 hours of track time??? No wonder they’re worn! What are your pressures? Are you rotating tires?
It’s hard to read the specs but they don’t sound extreme.
But 8 hours of track time??? No wonder they’re worn! What are your pressures? Are you rotating tires?
I follow GM's recommendation of 26psi cold, then as soon as I pull off track I bleed them back to about 30. This nets me a peak of around 33-34 during the session.
On corvettes if the camber bolts for the front slip it results in toe out, which destroys the inner shoulder. I always mark my camber cams with a white paint sharpie so I can see if they move and if they have, move them back to where they belong.
On corvettes if the camber bolts for the front slip it results in toe out, which destroys the inner shoulder. I always mark my camber cams with a white paint sharpie so I can see if they move and if they have, move them back to where they belong.
Mine were marked. If I squat down I can even see the rear ones and there is a slight offset from the original factory alignment, since I obviously had them dial it to the GM "competitive driving" spec.
The dealer tech looked at the tires today and said the wear looked consistent with a car that's been on the track. I drove over to Fall-Line for a second opinion and when I started talking about that new alignment spec it raised some eyebrows. I may have them replace the tires and fix the alignment.
I follow GM's recommendation of 26psi cold, then as soon as I pull off track I bleed them back to about 30. This nets me a peak of around 33-34 during the session.
No way to rotate these.
Rotate the tires from side to side. It's in the owner's manual.
It looks to me like the inside delaminated which isn't normal as its usually one of the center ribs that goes first. I attached my alignment sheet for my 17 gs and 2 pictures of my front tire after running on Road America for 10 sessions. I rotated them after the first day, but I am not on the inside edge at all, as -1.5 isn't nearly enough camber.
It looks to me like the inside delaminated which isn't normal as its usually one of the center ribs that goes first. I attached my alignment sheet for my 17 gs and 2 pictures of my front tire after running on Road America for 10 sessions. I rotated them after the first day, but I am not on the inside edge at all, as -1.5 isn't nearly enough camber.
Thanks -- it looks like you are a Z07 package though? The specified range is up to -2.1 for yours.
Thanks -- it looks like you are a Z07 package though? The specified range is up to -2.1 for yours.
I am just a 2lt with poverty aero, MPSS, nothing special. Stock everything but pads and srf. I think we just took whatever, so i think the car is actually fe5 maybe? My guy is a alignment only shop that more then half his work is race/track car alignments. So he just does whatever you ask including changing the acceptable zones on the chart, so don't focus much on that.
8 Track HOURS on a set of front tires??? Don't take this the wrong way, but I think you've got your money worth and you need to drive the car harder. I can't remember ever getting much more than a couple total hours of track time from a set of street tires.
Rotate the tires from side to side. It's in the owner's manual.
That won't do **** for the wear...
OP, how hard are you driving at the track, what experience level? What does the rest of the tire look like? Measure depth at several points of the tire. Have you used a temp gun to see if you're heating the tire equally across? (this would tell you if you have too much or too little camber for your specific track).
Since it's only 1 tire I bet your alignment slipped and you're high on Toe right now.
You need to get the alignment checked now. Those eccentric bolts have a way of moving under hard cornering loads.
Your settings look like you have borderline excessive toe out to begin with (I'm assuming positive toe numbers are toe out and negative numbers are toe in), and when the eccentric bolts slip, it generally results in more toe out. Your wear looks like toe-out damage more than camber issues.
Get the alignment checked again. When you find the excessive toe-out and the other "slipped" settings (I'm pretty sure it's changed since the alignment), have that corrected. When you have it properly aligned, before driving it, mark all the eccentric bolts with a paint pen so you know where they are. If it feels funny, or you see the start of weird tire wear, you can check your marks and see what, if anything slipped. For toe, go closer to zero. Any toe-out will wear the inner edges of the tires. It makes for snappier turn-in, but if you drive it on the street or put any significant highway miles on the thing, even slight toe out will eat tires.
EDIT: One more thing. Those tires look like they've been overheated. It's OK to use street tires for track days, but invest in a second set of wheels (with clonable TPMS sensors cloned to your existing ones, or get what you need to reset TPMS when swapping tires). On track days, run shaved street tires or real "R" compound tires molded with limited tread depth for track days. Shaving a street tire to 4/32 to 5/32 will make it last almost twice as long as running it brand new at twice that depth.
Last edited by C6_Racer_X; 07-20-2018 at 04:01 PM.
Sure it will. It is common to have more right hand turns for most people (freeway on ramps are typically right handlers for example) so it definitely can make a difference.
But, more importantly, if he is running tracks in the same direction, you will typically have four more corners in one direction per lap which will also cause uneven wear. Rotating side to side can even it out.
Originally Posted by BrunoTheMellow
Since it's only 1 tire I bet your alignment slipped and you're high on Toe right now.
All things being equal, more toe will likely show as a crooked steering wheel (unless both sides went out equally) and equal wear side-to-side.
My guess is just simple wear. 8 hours of track time is insane and the fact that just one tire is worn on the inside is likely due to the op running mostly/exclusively clockwise or ccw and not rotating tires (not saying he should or shouldn’t, just that it won’t help if he doesn’t.)
Yeah I could scrub off the corner of my left front in the carosel if i held speed in it one time. I had to use the little bit of self control i had to not destroy my front tires. Rotating it helped a bunch to balance the wear at the right front shoulder barely wore.
Granted i am not the fastest person ever. But the front left is 10-15 degrees higher by the end of every session, so it definately takes the most beating.
07-18-2018, 02:04 PM
Abnormal tire wear on C7 GS -- inside shoulder
