Azenis RT 660 missing strips of tread
 

After a lapping day, the front Falken Azenis RT660’s on my 2013 BRZ have circumferential strips of tread missing. The rear tires are fine.
The LF tire has a nasty groove right down the middle. At the worst spots the groove is 2/32" deep. The LF also has a very faint groove near the inside edge of the tread.
The RF only has a groove (3 of them, actually) near the inside edge of the tread, but it is a bit nastier than the inside edge groove on the LF. See pictures.
I reached out to technical@falkentire.com and received this email response from Christopher Guth, QA Supervisor with Sumitomo Rubber North America Inc.:
“…there is some lateral scrub happening on the tire shoulder, also evidenced by the greater wear on the shoulder compared to the middle of the tread. I agree that this does not look like a cut, but it is from lateral side forces “pushing” the shoulder tread inward. I can’t say that it is a defect since the tread construction is the same across the whole tread face (i.e. there are no construction joints that run circumferentially in that area with the 3 lines). Typically, we have seen in racing environments that this is due to camber and/or inflation pressure settings.”
I responded and asked if lateral scrub at the shoulder of the tire could account for a missing strip of rubber in the center of the tread and if the wear indicated pressures too low and too much negative camber. Guth’s email response:
“Any type of shoulder wear could indicate inadequate air pressure and/or incorrect camber. If both shoulders are wearing faster than the center then that would indicate too low of pressure. With too low of pressure (especially in a race setting) you would also have a “fold over” effect leading to the lines on the tread, including the line at the center of the tread. While I can look at the tire and read what is happening to it, unfortunately, we do not have data to provide on the optimum vehicle settings to avoid this type of wear. That would have to be more of a trial and error experiment for your particular vehicle. For that type of information I would direct you to forums and such other resources.
As for the wear itself, I would add that as long as you are maintaining proper inflation pressures this is not a safety concern, but more of a cosmetic issue.”
I’m not a tire expert and I may not fully understand Guth’s explanation. Has anyone else seen this kind of wear (I call them missing strips of rubber, Guth called them “lines on the tread”)? If so, what was the cause and what was the fix? Any suggestions for me?

I have seen other tires look like that but not the RT660. What tire pressure where you running?

My car is an automatic (=slow!) and to get every advantage in acceleration and speed, I tried size 205/40R16. With that tiny size, the load rating is significantly reduced, so 32 psi (cold) is the minimum pressure I use, and that on the drive to the track. Starting pressure for first session at the track is 34 front, 32 rear. Hot pressures coming off the track are 38-40 front and 36-38 rear.

That is strange you are getting that wear on the inside like that. What is your front camber?

On 245/40/17 I was usually running around 35psi hot with that tire though your different specs may change things a bit. I’d say temp probe them next time and see if you are getting abnormally hot in those area’s. I just don’t know what’s causing it and their explication doesn’t match what I see. To me, your pressures seem too high and usually unless you are running well over -3 degrees of front camber these cars tend to tear up the outsides off the fronts.

Here’s a pic of my RT’s after 4 track days. Wear is on outside edge even with -3.5 front camber.

https://uploads.tapatalk-cdn.com/202...a297239788.jpg

Thanks for posting a pic of your tires and your camber specs.
I run a lot of camber: -4 1/8 LF and -3 3/4 RF and zero toe. I've been willing to tolerate wear on the inside edge (much of which probably occurs on the 200 miles round trip street driving to and from the track) in order to lessen the wear on the outside edge. From what Guth with Sumitomo Rubber said, I wondered if high negative camber was causing the problem, but I still don't see how that caused the groove down the center of the LF tread. And Guth's statement that "Any type of shoulder wear could indicate inadequate air pressure and/or incorrect camber" caught my attention. I'm pretty sure shoulder wear is a fact of life with street cars like ours.

Yes I’ve seen this before on other rt660s, stories all over autocross forums and Facebook and Reddit. Glad you got the feedback from their QA that the solution is to just power through it and try not to overdrive em. They do like higher pressures is something I’ve heard pretty consistently.

All the stories I've previously seen about the 660s is about a slice across the tire where the seam between tread sections has come apart slightly. Happened with my own set. To which they tell you it'll be fine and keep driving.

This is the first I've seen with a grove with the thread.

Azenis RT 660 missing strips of tread
 

So I have noticed some heavier inside wear on tracks that have several long loaded corners at higher negative camber settings. I was digging through some tire pictures and I do have one where my left front was as worn on the inside as it was on the outside. I just attributed it to high static camber putting it up on the inside edge under load. Never had the wear you show though. Though I settled on 35psi hot, I had run anywhere from 33-37psi with the 660's.

https://uploads.tapatalk-cdn.com/202...58b82f41b5.jpg

Tread, no threads in tires, it's not a blanket.

I only spent about 5 minutes searching, here's some similar issues, plus the two or three sets I've seen do this in person that didn't get posted online.

https://grassrootsmotorsports.com/fo.../175273/page1/

https://www.reddit.com/r/Autocross/c...es_camber_and/

https://www.reddit.com/r/Autocross/c...rt660_tearing/

I may try less camber and keep pressure at 40 on my next track day (could be a while) and I'll update with the results. When I do go out, the rears will be rotated to the front and vice versa, so it will be easy to see if the grooving, if any.
Interestingly, this problem occurred on my second track day with these tires. The first time out, I put about 80 track miles on and the tires were fine. On that first outing, I had a stiffer front sway bar and a touch of front toe out--other settings were the same as the second outing. Ambient temps were low 90's for both outings. Second track day was about 85 track miles.

NoHaveMSG, the pic of your tire tread after 4 track days looks remarkably uniform and good to me. I am curious if you know about how many track miles that was.

Thanks to everyone for your comments.

Around 400, +/-25.

Thanks!

You really didn't read or understand my post did you?
I wrote tread, not thread.
And I said this is the first I've seen, not that this issue doesn't happen. Just so happens I have seen dozens of reports (my own included) about the tread splice issue.

Spelchek is ur frendd

I suggest proofreading before posting snarky reply.

Well there actually are but if you get to them then the tread wear is sort of a moot point.

Those are cords.

They stopped using weavers to make tires last century old man ;)

i *am* a tire expert - I would call this a 'flow crack' - when the belts shrink inward during curing, the uncured rubber flows in to fill the space, which sometimes causes rubber from the surface to pull down towards the belt edge. It's probably not very deep, just keep an eye on it.

For those are running 660's what PSI do use hot?

37 - 38

I ran 34-37.

On 245/40r17 on a 17x9 wheel, with -3f/-2.2r camber and 0 toe, I run them ~31 hot. This might be *slightly* low but I've got decently even wear across the tire although I can tell I'm wearing the outside more than the inside so I'm still not running enough camber but I've also got noticeably increased inner tire wear on my street tires so I'm not in a rush to go adding more, this seems like a decent middle ground since I'm not going to be getting a whole lot more out of either tire even with more optimized settings.

255/40r17 on 17x9, -4 camber in front, for autocross purposes I ran 29 in front, 28 in rear.
Temp probe showed even temps inside/outside/middle in the front. Rear was same outside/middle, little warmer on the inside.

As someone still fairly new to the world of performance driving and running non-stock tire widths I noticed a trend in the last couple of posts:

The wider the section width the lower the air pressure in the tire, even on wider wheels. Is this do there being less chance of the tire rolling over on the sideway because of the extra width, the additional negative camber being used, stiffer sidewalls on the wider tires, or a combination of factors?

I'll leaning heavily towards the 660's next season in 225 and trying to learn as much as possible to make any test-and-tune event be more productive.

If you are new and trying to learn as much as possible, don't run the RT660's. Like other super 200 tires, they are only good for a couple good laps before they drop off considerably unless it is cloudy and cold. If you insist on a 200TW tire, the V730 or RS4 are way better options as they will perform far more consistently over an entire session.

Thanks.

I used "new" as a relative term. I've got four AutoX seasons under my belt, but that's not much compared to a lot of folks here. Everything in the street classes in a couple different cars. I still fully admit to having plenty to learn. My real lack of knowledge is in running mods like 200TW tires.

I did manage to run a couple events in my previous car on a set of RS-4's for a couple of autox events and really liked them vs running on summer tires. They were my first introduction to a 200TW tire vs a summer tire I'd run before (PSS and PS4's). I was looking to step up in platform as well and initially thought about the RS-4's or RT615's, but the call of the 660's was strong since I'll the autox'ing them and won't really do any track days.

I may re-evaluate my plans.

AutoX'ing them should be fine since the run is so short, I probably shouldn't have just assumed you meant track work.

My experience is that the 660s can take a bit more heat than other tires in it's class. I'm primarily HPDE/lapping and just do autocross when something local is going on but at the very least, they hold up to lapping in comfortably warm weather (28c/82f) without significant fall off.

My impression in autocross on hot days (33c/91f) is that I can feel more grip in later runs as I get more heat into the tires, although perhaps my experience should be taken with a grain of salt given that I was the second slowest twin out of about a dozen at regionals this year, the only slower car was a complete novice while I've done track and autocross casually for the last ~6 or 7 years.

I'll chime in with my pressures on 225/45/17 660's. 31 front, 26, rear. Car also has a 19mm Perrin FSB on stiff, Sachs dampers, and that's about it.


As far as pressures, the general way I get to a certain pressure setup is to lower the front as low as possible to hit the triangles on the sidewalls. For this tire, that ended up being 31.

The rear is then tweeked to match the balance you want. With only -1.1 degrees of camber up front, 31 is the magic sauce there, but the rears need to be kept lower down at 26. I'm basically right on the triangles there and the car is general is going to push before the rear kicks out hard. I've set them to 28PSI with my co-driver and he immediately notices a difference and asks to lower them 2PSI... even when I didn't tell him I set the to 28.

I'd suspect with more camber up front, I could lower the front into the 28PSI range and the rears probably a bit lower too.

As far as the tire in general after 170+ runs the year, I'm not totally impressed. Price-wise, they're a good value. The wear well, but will heat cycle out near around 125 runs with more than half tread left. After about 150 runs, they really start losing grip. I've had RE-71R's and the drop off is about the same with those.

I had the A052 Yoks last year even on a ~1 degree low camber setup and they wore fine for me. Noticeably more grip and a better balance. I really like these more than the 660's, but they're $230/tire vs $165 in my size. For autox only purposes - if you're doing track too, the 660 is likely the ticket there.

Interesting. Myself and a few other local guys ran the RT660's and had similar experience. They loved them for autoX though. I don't do autox so can't comment on that.

Anything under 33 felt terrible to me but again, I don't autoX.

i'll say i had a similar experience at mid-ohio. they had good consistent grip throughout a lapping session, my confidence in them only dropped after ambient temps got to 85+ and a lot of rubber went down from NASA racing in the afternoon of a sunny day.