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I've started using Nanking AR-1's as track tires this season. Now that I've accumulated a good number of track miles, I'm seeing some strange wear patterns on these tires. Take a look at the circled areas in this photo and note how much more they are worn down than the rest of the tire:
This wear pattern appears along the entire circumference of the tire and it's the same on all 4 tires, front and rear. The outside of the tire is on the right side of the photo, so you can see the deepest wear is offset somewhat to the outside from center. I've tried different inflation pressures and I'm currently running hot pressures of 28 psi front and 30 psi rear.
Other info: The car is a 997.1 GT3. It's primarily a track car that only gets driven on the street to get to and from the track. The alignment specs are:
-2.6 deg front camber
0 front toe
8.0 deg front caster
-2.3 deg rear camber
0.2 deg rear toe-in per side
I have relatively new Motion Control 2-way adjustable coilovers with pretty stiff springs (700# front, 900# rear) and the suspension has all semi-solid monoball joints.
Otherwise the tire grip is very good and holds up very well with accumulation of heat cycles. However, the deep wear that you see in the photo ultimately limits the tire life. The inside and outside shoulders show much less wear.
I was thinking this kind of wear could be caused by overinflation, but I've been trying progressively lower pressures and it doesn't seem to make much difference.
So, what could be causing this strange wear? Should I try even lower pressures?
The graininess of the tire identicates the tire is overheating in that area
More negative camber could help or the car is understeering in s9me portion of the corner, ie, cannot rotate, which says the front is too stiff
I should also mention that before running the AR-1's, I had Sport Cup 2's with the same car setup. The Sport Cups never did this. I think it's something specific to the Nankings.
Well they r 2 completely different tires that i am sure that perform very differently on the track so comparing them means very little.
I doubt it has anything to do with the tire and a lot to do with the set up and driving style. But then again im kinda a new guy here but that guy in post 3 seems to really know his $hit. Good luck.
The stickier the tire, the more camber will be required (all things equal), but even that is simplistic.
You are looking for evening temps within reason across the tread. That said, front sliding (understeering) whether by technique or setup will roast the outsides, and adding more camber after a certain point will decrease straight line traction and most importantly braking. In other words, the most even tire wear is not necessarily 'optimal' other than for your wallet.
As for a quick comparison, I am running a 996 GT3 with MCS 2-way. With NT-01, I run 3.2 to 3.4 front negative camber. I still end up with 'some' excess outside wear, and flipping before too late buys me a bit better lifespan.
So long story, with the stickier AR-1, 2.6 front neg camber is simply not enough. Similar thought process applies to the rears, though the average driver is more likely to understeer/push than over-rotate.
It's not Nankang specific tire wear, probably a combination of setup and/or use factors.
28 psi hot is pretty low. Your starting pressures? Any signs of sidewall rollover?
If you're wearing toward the outside shoulder with -2.6 camber, try a bit more camber and increasing psi to low 30's hot.
As always with these tires and those like them, tread grooves are worth next to nothing. Not to say you shouldn't experiment to see if you can even out, but the pictured wear isn't a big problem, they don't look close to "done."
The stickier the tire, the more camber will be required (all things equal), but even that is simplistic.
You are looking for evening temps within reason across the tread. That said, front sliding (understeering) whether by technique or setup will roast the outsides, and adding more camber after a certain point will decrease straight line traction and most importantly braking. In other words, the most even tire wear is not necessarily 'optimal' other than for your wallet.
As for a quick comparison, I am running a 996 GT3 with MCS 2-way. With NT-01, I run 3.2 to 3.4 front negative camber. I still end up with 'some' excess outside wear, and flipping before too late buys me a bit better lifespan.
So long story, with the stickier AR-1, 2.6 front neg camber is simply not enough. Similar thought process applies to the rears, though the average driver is more likely to understeer/push than over-rotate.
Cheers
Matt
I think the next step is to measure hot tire temperatures and see what's going on across the tire. I don't think it's a simple case of understeering because that would affect the front tires. However, both front and rear tires on both sides of the car are exhibiting the same wear pattern. I could add more negative camber, but I have to make a compromise to accommodate street driving. With too much negative camber, I know from experience that the inside shoulders of the tires will get destroyed from street driving.
Other than the uneven wear, I'm actually pretty happy with the AR-1's. They are quite similar to NT01's in terms of longevity and grip, but the problem is nobody stocks NT01's these days in the sizes I need (235/30/19 and 305/30/19) and the Nittos are much more expensive than the Nankings. At 30 heat cycles, the AR-1's still have good grip left but I'm wary of cording them because of the deep wear pattern. The Cup 2's are a much inferior track tire, although a better street tire, because they have such a short heat cycle life.
It's not Nankang specific tire wear, probably a combination of setup and/or use factors.
28 psi hot is pretty low. Your starting pressures? Any signs of sidewall rollover?
If you're wearing toward the outside shoulder with -2.6 camber, try a bit more camber and increasing psi to low 30's hot.
As always with these tires and those like them, tread grooves are worth next to nothing. Not to say you shouldn't experiment to see if you can even out, but the pictured wear isn't a big problem, they don't look close to "done."
I've tried higher pressures, up to 35 psi, but the wear pattern is still pretty much the same. The only concern about the wear is the cording that will occur when the tread is worn through. Otherwise with more even wear, it would seem I could get much more tire life. The AR-1's don't seem to be limited much by heat cycle life.
Yup, sounds like you're on the right path. Truth is, if it's truly a 'dual-use' car, then you're probably close to the limit of what will work for you.
If your usage has any meaningful or enjoyable amount of street driving, you have to decide what's more important. I personally run cheap 'sacrificial' street tires, but that's because I basically only drive to and from the track and the shop and trailer my track wheels. I wouldn't be happy ruining nice Michelins in my use case.
If I reverted to true 'dual-use' and wanted to enjoy good tires on the street as well, I'd probably de-tune the car to run on Michelins. Street tires, street-ish alignment - definitely compromised for the track, but everything dual-use is.
If you're close to that compromise alignment, maybe it's as simple as a tire dismount/flip. Just do it early enough, don't wait till too late.
I've tried higher pressures, up to 35 psi, but the wear pattern is still pretty much the same. The only concern about the wear is the cording that will occur when the tread is worn through. Otherwise with more even wear, it would seem I could get much more tire life. The AR-1's don't seem to be limited much by heat cycle life.
Maybe, but dollars to donuts you'll find them limited by heat cycles prior to wear/cords. I don't know what I'd have to do to wear my set to cords, but they're heat cycled now.
You're familiar with NT01, I'd think of any disappearing tread as similarly unproblematic on AR-1. Go ahead and monitor but don't sweat this level of uneven wear. What you've pictured would be a minor miracle on so many other platforms after 30 heat cycles. Porsche guys are spoiled.
Maybe, but dollars to donuts you'll find them limited by heat cycles prior to wear/cords. I don't know what I'd have to do to wear my set to cords, but they're heat cycled now.
You're familiar with NT01, I'd think of any disappearing tread as similarly unproblematic on AR-1. Go ahead and monitor but don't sweat this level of uneven wear. What you've pictured would be a minor miracle on so many other platforms after 30 heat cycles. Porsche guys are spoiled.
The AR-1's in the two links you provided appear to be showing a wear pattern very similar to mine! The deepest wear is just off the center of tires. In the photo in the second link, you can see this pretty clearly because there is still tread depth on the inside and outside shoulders of the tires, but not so much just off the center. Of course, we don't know how the cars were set up in these two cases, so it's somewhat "circumstantial" evidence.
I can live with this because as I said before, I'm pretty happy overall with the performance of these tires compared to the alternatives, and especially for the price.
The AR-1's in the two links you provided appear to be showing a wear pattern very similar to mine! The deepest wear is just off the center of tires. In the photo in the second link, you can see this pretty clearly because there is still tread depth on the inside and outside shoulders of the tires, but not so much just off the center. Of course, we don't know how the cars were set up in these two cases, so it's somewhat "circumstantial" evidence.
I can live with this because as I said before, I'm pretty happy overall with the performance of these tires compared to the alternatives, and especially for the price.
Just outside of center is a common high wear area. Here's a front Supercar 3R off another platform, also running about -2.6, but this is after 7 heat cycles. Yes, AR-1 are excellent performance & longevity for the money, have fun.
07-07-2022, 12:33 PM
Strange tire wear on Nanking AR-1
