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Is something wrong here (tires, alignment)?

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45
36
Exp. Type
HPDE
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Under 3 Years
Spain
After my fourth trackday a few weeks ago my front tires looked really ugly with a lot of uneven rubber on them. That seems to have "rubbed off" since, but based on a bad photo elsewhere somebody else suggested my tracking / alignment may be out and that I'd scrubbed the outside shoulder of the tyre. I can't see it myself, but I'm not competent enough to say anything about that, so does anyone see something wrong here?


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Bill Pemberton

0ld Ford Automotive Racing Terror
8,380
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Blair, Nebraska
There are numerous answers, but this is part of the reason many TMO members have suggested you get camber plates as one of your first mods. Think of your tire/wheel as being straight up and down and when you go around a corner quickly it loads the tire and the g forces will fold the tire under some. With camber plates you can get a certain degree of negative camber , which visually makes the tire/rim look like it is folded in at the top edge and sitsout at the bottom. The means the viewed stance would appear that the bottom of the tire is bouyed out at the bottom and angles inwardly at the top. Therefore when you go around corner quickly , the forces push in on the tire and instead of folding it in where it wears the inside of your tire, it tends to push it in to keep the entire tire on a somewhat flat stance , wearing across the entire surface. I hope this is helpful and I tried to make the concept fairly simple since I am not acquainted as to how good your English is, though in your postings it appears to be quite excellent.
 
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Grant 302

basic and well known psychic
Uh, I think your English is fine. And lack of static camber is likely part of your alignment issue. But I would also guess that you could or should be running more pressure. What was your pressure hot?

Performance Michelins have a dual-compound tread and the outer block is softer than the rest. Managing pressure hot and camber are key to reducing this type of wear.

I’ve used the first generation of Super Sports as a street/track tire and I’d only use them for rainy conditions. I’d choose something else for a dual purpose dry tire. Like RE-71.
 

Grant 302

basic and well known psychic
I don't think they are crazy horrible, and a pressure increase would help, but IMO is a band aid, more camber is likely your answer, and as stated, when these wear out, try a different brand of tire. The Michelins are great tires, but they do have their limits.
Static camber is also a band-aid. Like we discussed not long ago, caster and camber gain properties are the ones to chase IF the pressure is right.

But dealing with the soft sidewall and the dual compound tread isn’t as easy as just screwing with the camber on a dual purpose car Just sayin’.
 
6,299
8,033
Static camber is also a band-aid. Like we discussed not long ago, caster and camber gain properties are the ones to chase IF the pressure is right.

But dealing with the soft sidewall and the dual compound tread isn’t as easy as just screwing with the camber on a dual purpose car Just sayin’.
The very fact that it is a dual purpose car makes it difficult
 

Grant 302

basic and well known psychic
The very fact that it is a dual purpose car makes it difficult
Yes and no. I don’t have to change a thing unless I’m making a small track specific adjustment. I suspect that can be done on an S550 since they start with better camber gain properties.

And that’s why I’d say changing the camber only is also just a band-aid solution.
 
45
36
Exp. Type
HPDE
Exp. Level
Under 3 Years
Spain
Many thanks for all the comments. I will try to add the Vorshlag camber plates so many of you all recommend to the next USA parcel-forwarder order that I'm currently building up. I also appreciate all the hints that I should do that sooner than later, and my only hesitation is due to since it being the case of me installing them myself, I'm a bit heistant to start with the most difficult install first (I like to turn wrenches, but pre-Mustang it has only been on motorbikes). After I have installed them I will also try to source a set of 19x11 wheels as recommended so I can get some more long-lasting and cheaper tires suitable for trackdays.

Regarding pressure on my Michelin ps4s tires, they are around 31-32 psi (cold) for my daily driving according to the tpms (which is mostly inline with my cheap tire pressure gauge), and rose up to 36-38 psi hot during my last two trackdays (according to tpms). Might have seen 39 psi once or twice too, though I only look at the tpms display sometimes (three-four times during a trackday?). Does this seem like a decent value for me?

I thought I'd sooner lower them than raise them, but judging from your comments I guess I'm wrong in thinking that?
 

Grant 302

basic and well known psychic
A 255 is a ‘dinky’ little tire for cars this heavy. When I ran on the original Pirelli 255 on the stock front geometry I used up to ~42 hot to ‘control’ the roll-over. And that’s with a stiffer sidewall. With 265 Super Sports and a whole bunch of suspension changes (CC plates, P springs and Boss dampers), I used a wide range of adjustments in order to have reasonable wear. And still needed to use different street and track settings. Wear was a bit strange on the tread blocks with so much static camber. Used other tires in between. With even more suspension changes (CorteX 550# coilovers w/ very different settings) and using the same size Super Sports just for street and rain duty, I found the same tires would grip much better even with reduced static camber, but better camber gain properties.

I think the next thing to focus on are running larger tires. But since rotating tires won’t help on the stock staggered setup (maybe switching sides Left-Right might help a bit), I’d still use a bit more pressure on these if you use them up before getting new ones.
 
45
36
Exp. Type
HPDE
Exp. Level
Under 3 Years
Spain
I think the next thing to focus on are running larger tires. But since rotating tires won’t help on the stock staggered setup (maybe switching sides Left-Right might help a bit), I’d still use a bit more pressure on these if you use them up before getting new ones.

Thanks for the suggestion. As you say I can't rotate the tires with my stock setup, but as the track has about 50% more right turns than left turns, I too figured it might help a bit if I swap the tires from the left to the right side between trackdays.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
8,380
8,261
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
Grant is correct and that is why, eventually , one of your early mods would be to get a set of squared rims so you can rotate tires around often. You have noticed many of us use Apex, and I would contact them direct. Click on Sponsors and when it rolls down to Apex , you will note there is a link for the TMO Representative. This will get you to Cory, who helps all the folks on the Forum and he might be able to help you with your choices.
 
45
36
Exp. Type
HPDE
Exp. Level
Under 3 Years
Spain
There are numerous answers, but this is part of the reason many TMO members have suggested you get camber plates as one of your first mods. Think of your tire/wheel as being straight up and down and when you go around a corner quickly it loads the tire and the g forces will fold the tire under some. With camber plates you can get a certain degree of negative camber , which visually makes the tire/rim look like it is folded in at the top edge and sitsout at the bottom. The means the viewed stance would appear that the bottom of the tire is bouyed out at the bottom and angles inwardly at the top. Therefore when you go around corner quickly , the forces push in on the tire and instead of folding it in where it wears the inside of your tire, it tends to push it in to keep the entire tire on a somewhat flat stance , wearing across the entire surface. I hope this is helpful and I tried to make the concept fairly simple since I am not acquainted as to how good your English is, though in your postings it appears to be quite excellent.

Many thanks, that was a good and easy to understand explanation.
 
There are numerous answers, but this is part of the reason many TMO members have suggested you get camber plates as one of your first mods. Think of your tire/wheel as being straight up and down and when you go around a corner quickly it loads the tire and the g forces will fold the tire under some. With camber plates you can get a certain degree of negative camber , which visually makes the tire/rim look like it is folded in at the top edge and sitsout at the bottom. The means the viewed stance would appear that the bottom of the tire is bouyed out at the bottom and angles inwardly at the top. Therefore when you go around corner quickly , the forces push in on the tire and instead of folding it in where it wears the inside of your tire, it tends to push it in to keep the entire tire on a somewhat flat stance , wearing across the entire surface. I hope this is helpful and I tried to make the concept fairly simple since I am not acquainted as to how good your English is, though in your postings it appears to be quite excellent.
@Awk I'm a visual learner and have to see or visualize things to completely understand the how and why of things. About 3/4 the way down the BND Techsource home page there are pretty good illustrations of @Bill Pemberton 's description of the deformation of a tire with and without negative camber. The next to the bottom photo illustrates the other half of camber plates - to go back to a reasonable camber for street use if a dual use car.

FYI to anyone reading this post - you have to check out all of the BND website. There is so much cool info.
 

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