Tire whisperers

[JAL racing]

Any tire whisperers out there who might be able to tell me what this wear says? This tire has 100 miles of track time.
I don't know how to assess whether it is fine or not. I have the impression it is wearing evenly. IR gun says inside, centre and outside temperatures are within ten degrees with the inside being the hotter part after a session.
Specifically, I don't know how to judge whether it is wearing too close to the outside sidewall or if what we see in the picture is fine. The cold pressure was 29 and hot was 36
Thanks!

 

[blacksheep-1]

It appears to be just tire degradation from heavy track use, and a good dose of heat thrown in. My forte is slicks, not treaded tires, but I will try to help you out. Generally, treaded tires retain more heat, so you get more surface pitting than slick tires, The IR gun is not a great way to measure, a Longacre memory probe is much better, but then I understand it would take 2 people. Also don't get fixated on even across the tread temps, that may be OK for formula or prototype cars, but not for production based vehicles that use a lot of mechanical grip and camber to get things done. One way to check your tire "rollover" is by using chalk on the sidewall and seeing how much is rubbed off.
Is this a front, or rear?

 

[JAL racing]

Is this a front, or rear?

Thanks Blacksheeep, it's a front. I knew about the chalk trick, just not how to interpret it. If you look at the picture, should the tire be allowed to rollover up to the #1, 2 or 3 arrow? It looks to me like there is two different rubber compounds meeting at the tip of the #3 arrow...

 

[blacksheep-1]

Thanks Blacksheeep, it's a front. I knew about the chalk trick, just not how to interpret it. If you look at the picture, should the tire be allowed to rollover up to the #1, 2 or 3 arrow? It looks to me like there is two different rubber compounds meeting at the tip of the #3 arrow...

View attachment 66948

there kind of is, at some point there you will hit cord. The sidewall is usually 2 ply, the tread area as many as 4. You are starting to wear into the bonding strip between the two, but you have a ways to go yet. If I was to tell you 1 thing to do it would be add pressure so the tire is more upright, but that is a stop gap solution, a better one would be more camber. You are really giving that sidewall a workout.
Sometimes you can go into the rabbit hole of death. basically the car pushes, or the tire rolls over, builds heat, rolls over more, more steering input, more roll over etc, until the tire blisters on the side
this is my "favorite track" Homestead, you can see the tire deformity and how the tire is trying to pull itself off the bead.
this is an extreme case, but you get the idea.

 

[JAL racing]

there kind of is, at some point there you will hit cord. The sidewall is usually 2 ply, the tread area as many as 4. You are starting to wear into the bonding strip between the two, but you have a ways to go yet. If I was to tell you 1 thing to do it would be add pressure so the tire is more upright, but that is a stop gap solution, a better one would be more camber. You are really giving that sidewall a workout.
Sometimes you can go into the rabbit hole of death. basically the car pushes, or the tire rolls over, builds heat, rolls over more, more steering input, more roll over etc, until the tire blisters on the side
this is my "favorite track" Homestead, you can see the tire deformity and how the tire is trying to pull itself off the bead.
this is an extreme case, but you get the idea.
View attachment 66952

I see what you mean. I thought this setup I have was the best driving experience I enjoyed so far in terms of grip and how predictable it was, even compared to my previous 200 tw tires. These are MPS4S and I thought I would sacrifice grip for durability but my app shows better sustained lateral G than before. Maybe it is experience kicking in I don't know.
I realize the real fix for good grip is to go with used slicks but I need to get a better appreciation of the costs over time. Ideally I'd like to keep tire costs under 3k per year (50 sessions of 20 minutes approx) and I don't know if I can do that with a pallet of 16 Michelin slicks shipped to Canada or if I would need more.

 

[blacksheep-1]

I see what you mean. I thought this setup I have was the best driving experience I enjoyed so far in terms of grip and how predictable it was, even compared to my previous 200 tw tires. These are MPS4S and I thought I would sacrifice grip for durability but my app shows better sustained lateral G than before. Maybe it is experience kicking in I don't know.
I realize the real fix for good grip is to go with used slicks but I need to get a better appreciation of the costs over time. Ideally I'd like to keep tire costs under 3k per year (50 sessions of 20 minutes approx) and I don't know if I can do that with a pallet of 16 Michelin slicks shipped to Canada or if I would need more.

Stay with the 200TW tires, that's what most run in HPDE so you can use that as a barometer to see how you are improving as a driver. Those Michelins are around $2800 / set US, New.
At some point you'll need to go 18inch as those tires are most prevalent as take offs. You may try Multimatic, they are Canadian and should have take offs available

 

[JDee]

Without camber you're never going to get away from this problem. These cars need upwards of -4, tough to get that but -3 to -3.5 will increase grip as well as reduce that wear, you can get that with Vorshlags plates. It will eliminate tearing that outside shoulder up, assuming you've got correct pressure.

 

[blacksheep-1]

Without camber you're never going to get away from this problem. These cars need upwards of -4, tough to get that but -3 to -3.5 will increase grip as well as reduce that wear, you can get that with Vorshlags plates. It will eliminate tearing that outside shoulder up, assuming you've got correct pressure.

an assuming his rules set allow him to do it

 

[JAL racing]

an assuming his rules set allow him to do it

JDee, Blacksheeep, thanks for the comments. No specific rules except safety for HPDE here. Hot pressure is 36 psi. I have BMR camber plates and apparently, 2.2 degrees is the most the alignement shop could give me. I doubt that... check this out:

 

[blacksheep-1]

I would say -3 is the absolute minimum for these cars. The big problem with a lot of alignment shops is that they get hot and bothered every time you go past mfg specs. I went through this when I had a set of slicks mounted at Walmart (not my first choice but..) they had it in their minds that I was going to complain about the work and want new tires or some such garbage. I have managed , over th last 10 years to cultivate my local Goodyear store into doing what I ask. Since they now know me by name I can get pretty much any tire/alignment issue handled. I do bring my wheel/tire assemblies in squeaky clean and with no weights. A lot of time the owner just says to throw the guys in the shop a bone, no receipts. which is fine with me.

 

[JDee]

I had MM plates first and they were only good for -2.2 as well as having a bearing that would seize and start to saw into the strut shaft. Low quality hardware made it not money well spent.

 

[JAL racing]

I had MM plates first and they were only good for -2.2 as well as having a bearing that would seize and start to saw into the strut shaft. Low quality hardware made it not money well spent.

Since I already have the BMR CP installed, maxed out at -2.2, and they appear to be very strong, would I not be better off to add adjustable LCA for what I'm missing in camber and get the benefits of increased track width? Like the ones from SPL?
Instead of getting rid of the BMR CP and replacing with Vorshlag?

 

[JDee]

Since I already have the BMR CP installed, maxed out at -2.2, and they appear to be very strong, would I not be better off to add adjustable LCA for what I'm missing in camber and get the benefits of increased track width? Like the ones from SPL?
Instead of getting rid of the BMR CP and replacing with Vorshlag?

I don't have enough knowledge of geometry to be able to speak to that, I'm sure other people will. I like the KISS way of doing things, so if I can get the full amount of adjustment I want with one thing I'd go that way before adding something else to the mix, another variable is often not good.

I'm also not sure how useful some of the esoteric minutiae is when you're dealing with non-purpose built race cars and DOT tires. We've got tons of compliance in the suspension, race cars with rod ends and so on have none. But again, I know little to nothing about that for certain.

Another way you can get more camber in lieu of buying new plates is to slot the mounting holes, or even re-drill new ones, as @carver did to great success.

 

[RBELUN]

Since I already have the BMR CP installed, maxed out at -2.2, and they appear to be very strong, would I not be better off to add adjustable LCA for what I'm missing in camber and get the benefits of increased track width? Like the ones from SPL?
Instead of getting rid of the BMR CP and replacing with Vorshlag?

Add some camber bolts. I was able to get to -3 on my 18 with 275/30/19 on 19x10 wheel. Now with JM plates and bolts and a 25mm spacer and 305/30/19 on 19x11 wheel I have -4. Look at camber bolts. Looks at longer wheel studs and a spacer. The turn in and grip from the added width is amazing.

 

[JAL racing]

Add some camber bolts. I was able to get to -3 on my 18 with 275/30/19 on 19x10 wheel. Now with JM plates and bolts and a 25mm spacer and 305/30/19 on 19x11 wheel I have -4. Look at camber bolts. Looks at longer wheel studs and a spacer. The turn in and grip from the added width is amazing.

Thanks! It's good to know I can do CP and bolts too. I thought bolts would not work with 305 tires since it is already so close to the strut with the spacer (my bolt-on spacers are 30mm, the wheels are 56mm offset). I'll order a set of bolts!

 

[Norm Peterson]

Thanks! It's good to know I can do CP and bolts too. I thought bolts would not work with 305 tires since it is already so close to the strut with the spacer (my bolt-on spacers are 30mm, the wheels are 56mm offset). I'll order a set of bolts!

The closer your tire/wheel to strut clearance gets, the less negative camber help you're going to be able to get from camber/crash bolts. Bolts may advertise ±1.75°, but when strut clearance can only be reduced by 1/16" you're only going to be able to use about 0.3° of that.

Bolt-on spacers for track duty isn't a great idea. But if you need the 30mm you should be able to press out the spacer's wheel studs and use them as slip-on spacers. You will need longer studs installed in the hubs.


Norm

 

[JAL racing]

The closer your tire/wheel to strut clearance gets, the less negative camber help you're going to be able to get from camber/crash bolts. Bolts may advertise ±1.75°, but when strut clearance can only be reduced by 1/16" you're only going to be able to use about 0.3° of that.

Bolt-on spacers for track duty isn't a great idea. But if you need the 30mm you should be able to press out the spacer's wheel studs and use them as slip-on spacers. You will need longer studs installed in the hubs.


Norm

Thanks Norm... at the time I did my research bolt-on seemed like the way to go and the more I read the forum, the more I see slip-on with long studs as the preferred way. I accept this wisdom but truly, wouldn't the wheel itself be more likely to break than my additional 5 studs of graded steel on each wheel? The wheel is light alloy and gets fitted and removed a couple of times a week. I am inclined to think this will fail long before my spacer studs, wouldn't you agree?

 

[Norm Peterson]

Lug nuts tend to loosen in service, and loose lug nuts eventually tend to let bad things happen.

With 10 lug nuts per corner instead of just 5 you've doubled the number of failure points, and half of them are not readily accessible for lug nut torque checking in paddock.


Norm

 

[TMSBOSS]

Add in the strength of the ARP studs over stock and the swap to a longer stud is the way to go. Flex in the bolt on spacer is also a concern for me. The full length stud will sandwich the spacer and not allow flex to occur.

 

[Scootsmcgreggor]

Also the interference fit of the studs in the aluminum spacer is much less robust than studs in steel hubs. So they can work loose and possibly shear more easily.

You can press the studs out as Norm suggests. This is the route I went since I had the spacers already and they work just fine.