[5thgear]

Originally Posted by cdb95z28

ZL1+911 askes a good question. I think guys are going balls out on lap one with the low recommended pressures. I'm guilty. For the ZLE, the recommended cold pressure is 26psi. In my experience, that seems like asking for trouble as far as shoulder wear goes. If a driver has discipline on those first 2 laps, then that goes a long way to helping the tires. It's a double edge sword. I'd like to see the outer shoulders of those same tires.



Other variables like track surface/layout, etc. probably matter too.

Thank you for sharing your thought. Attaching pics showing the outside of the same tires.
The track runs CCW and wears right side / passenger side tires faster

[cdb95z28]

Originally Posted by Zl1+911

Having gone through a few sets of GY3Rs, and tried a few different things, here are my learnings till date -

1) I don’t think any one thing completely helps
2) BMR toe arm with lockout nut
3) alignment - see below
4) cold GY3Rs and a fast lap don’t go together- this causes premature wear on the inside - I do my first session with slightly higher pressure- start at 31 front and let them go up to 37/38, bleed air after first session to hot 35 fronts
5) if you need to drive to and fro to the track on these - keep them at 35 or higher
6) check insides after EVERY session and Flip as needed - both left to right and inside outside

Originally Posted by Zl1+911

I now go with negative toe for this exact reason. I get no inside wear now. It could be other things too - but negative toe helps for sure. I was tired of destroying new set of tires in few sessions on the inside.

Toe figures that are negative are toe out.
Toe in is always positive.

That picture of the alignment sheet is showing toe out. Notice the rear is positive, it is toe in, as the rear is always toe in, unless you like to live dangerously, haha.

Originally Posted by 5thgear

Thank you for sharing your thought. Attaching pics showing the outside of the same tires.
The track runs CCW and wears right side / passenger side tires faster

I should have clarified better, a picture of the sidewall and the shoulder.

[cdb95z28]

Originally Posted by cdb95z28

Look at the shoulder on the tire in the first picture. That is not a toe issue. It's abusing the shoulder. Whether it is low pressure combined with aggressive early lap driving and/or inadequate camber dynamic camber control is the question. I've run toe in on my Gen5 and have and the same wear of my 3R.

The graining pattern on that shoulder/sidewall is similar to what we can see on the outer shoulder/sidewall of a tire with inadequate negative camber, where the tire rolls over the shoulder. It rolls so much that the sidewall is getting into the track surface. This is that in reverse. Not enough positive camber (dynamically) or too much negative camber. It's happening to the inner/less loaded tire during a turn. Now when I say not enough positive camber on the unloaded inner tire, it most likely doesn't go into positive camber. Atleast not when the static camber is high like we run on our cars.

In reality, as the car rolls, that inner unloaded tire moves away from negative camber. But on MacStrut cars, the camber curves suck so much that there is still alot of negative camber on that tire, and it ends up dragging that inner shoulder as the car proceeds thru the turn.

ZL1+911 askes a good question. I think guys are going balls out on lap one with the low recommended pressures. I'm guilty. For the ZLE, the recommended cold pressure is 26psi. In my experience, that seems like asking for trouble as far as shoulder wear goes. If a driver has discipline on those first 2 laps, then that goes a long way to helping the tires. It's a double edge sword. I'd like to see the outer shoulders of those same tires.

But I think this also points to an inherent flaw on the fronts of these cars because of the MacStrut. The camber curves suck.

Other variables like track surface/layout, etc. probably matter too.

Here's a ZLE owner at my track. Pitt Race, turn 1. Notice the LF tire. It is the inner less loaded of the two fronts. Look how the tire is more on the inner half. I suspect it's dragging that inner shoulder a fair amount. Add in Ackerman and more toe out that probably makes it worse. While Ackerman and the toe out help create grip at that tire, grip=tire wear. And we are seeing too much at that inner half. If we had better camber control at the LF, then the tire would be more flat, more of the tread would be utilized.

And the use of camber plates which adds SAI, may actually be hurting all of this. And my Gen5 is in the other pics, same corner.

[5thgear]

Originally Posted by cdb95z28

Toe figures that are negative are toe out.
Toe in is always positive.

That picture of the alignment sheet is showing toe out. Notice the rear is positive, it is toe in, as the rear is always toe in, unless you like to live dangerously, haha.





I should have clarified better, a picture of the sidewall and the shoulder.

Sure. Here is couple photos

[cdb95z28]

Which one are the fronts?

[cdb95z28]

They don't look bad at all. Maybe a touch too much into the Goodyear emblem in the 2nd and 3rd pic. At times I've completely worn my to the point where the emblem is gone.
These are the same tires that have worn thru on the inner shoulder, correct?

[5thgear]

Originally Posted by cdb95z28

Which one are the fronts?

Oh.. just different angels of both fronts. The Same two with corded inners

[cdb95z28]

Got it. It's a tough balance to try and find. Killing the inner shoulder makes you want to reduce the neg camber, but you'll have to baby the tires till they gain some temp/pressure so the outer shoulder lives. But right now, those current tires are telling us to run less negative camber.


But as I mentioned, there are other factors in play. I'm not convinced the inner shoulder wear is only a toe out problem. Maybe the toe out plays a part, by causing some of the dragging along of the inner less loaded tire. I think all that neg camber on that inner tire is the main problem. I have an article I found that talks about toe and ackerman. I'll try to dig it up....

[Zl1+911]

I am running -3.1 camber with the toe out settings (post 58) - zero inner wear now

[5thgear]

Originally Posted by cdb95z28

Got it. It's a tough balance to try and find. Killing the inner shoulder makes you want to reduce the neg camber, but you'll have to baby the tires till they gain some temp/pressure so the outer shoulder lives. But right now, those current tires are telling us to run less negative camber.


But as I mentioned, there are other factors in play. I'm not convinced the inner shoulder wear is only a toe out problem. Maybe the toe out plays a part, by causing some of the dragging along of the inner less loaded tire. I think all that neg camber on that inner tire is the main problem. I have an article I found that talks about toe and ackerman. I'll try to dig it up....

In my case I am running zero toe and -2.9 camber. As you see the outside is not bad. I assume if the tires were pushed with low temp / pressure then outside would show unusual wear. I am going to try another set of fronts next month and keep pressures higher than 34 psi and see. Try some of the tips mentioned.

[cdb95z28]

Originally Posted by 5thgear

In my case I am running zero toe and -2.9 camber. As you see the outside is not bad. I assume if the tires were pushed with low temp / pressure then outside would show unusual wear. I am going to try another set of fronts next month and keep pressures higher than 34 psi and see. Try some of the tips mentioned.

I think the higher starting pressures will help the shoulders for sure. It just takes longer for the tires to come up to temp. Heat from the brakes also play a part. The big thing is, will the contact patch be close to optimum? Please let us know how you make out. I'm done playing till spring here in PA.

[Zl1+911]

5thgear look forward to your reporting back on how things progress....

[h018871]

Good stuff, sub'd

[Pcormier66]

If you have the time and inclination, you could set your alignment based on the track and direction. Generally speaking, less neg camber on left side front for CCW tracks and less on R for CW tracks. You will generally be faster with better tire wear. Think of how NASCAR sets alignment for oval courses, but applied to a road course. For me, it's more about convenience. I prefer a set it and forget it, and live with faster tire degradation. I do my own alignments and just don't have the desire to reset for every event. I go to about 5 different tracks per year.

Many moons ago we had a pro race team supporting a DE event with tire and service at Motorsport Ranch Cresson CCW The owner and driver put on a clinic about the trade-off between lap times/tire wear and the time/$ to change alignment settings for every track and configuration. He had proven that for a vette, -1.3 camber L and -2.7 camber R, yielded the fastest lap times and best tire wear.