1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

What's causing my Pirelli SC2 tire wear pattern issue?

Discussion in 'Tech' started by DmanSlam, Mar 6, 2021.

  1. DmanSlam

    DmanSlam Well-Known Member

    Before I replace tires, I need to solve a tread wear problem.

    I have two gsxr 600 track bikes that I use for track days and riding schools. I typically run Dunlop Q3+ tread.

    Last October, I ran a Sat/Sun track day weekend at Summit Point main. Halfway through day 1, I changed one bike over to Pirelli Diablos (SC2) since it was abnormally cool (and quite cold at night) and used my tire warmers to avoid the cold tire crash and slow warm-up laps. Total track time on the Pirellis was 1.5 days of riding.

    The right-side of the rear has a huge wear pattern that I'm sure is cause for concern. I flipped the tire but that puts my concern on the left-side now.

    I used a pencil gauge and a buddy's motion pro gauge. My pencil gauge was reading 0.5 lower so I accounted for that if I used it. I forget the tire pressure I ran but it was the MDM vendor's recommendation--it was low 20s. Being able to recall that would be helpful obviously.

    I referred to this article but I'm only enlightened: https://lifeatlean.com/motorcycle-tyre-wear-guide/

    So, questions:
    a) is this a cold tear or a hot tear?
    b) is this a suspension issue?

    I had MRM set up my frontend but only set the sag on the rear. It's OEM shock (not sure about the spring).
     
  2. DmanSlam

    DmanSlam Well-Known Member

    156577427_273696097528456_7308189328052248045_n.jpg 156577427_273696097528456_7308189328052248045_n.jpg 156577427_273696097528456_7308189328052248045_n.jpg 156577427_273696097528456_7308189328052248045_n.jpg
     

    Attached Files:

  3. metricdevilmoto

    metricdevilmoto Just forking around

    Were you on shore power or running off a genny? What brand warmers? Cord? Was the Motion Pro gauge verified as accurate you were using as a control for the pencil gauge (that you should throw in the trash)?

    Also, if I was the vendor at the track, I would be exponentially more helpful to you that day, at the track. That's what I'm there for.
     
  4. rice r0cket

    rice r0cket Well-Known Member

    Did you take tire temperatures after getting off track?
     
  5. damiankelly

    damiankelly Well-Known Member

    Not knowing all the facts.... I would say that’s a rear suspension issue.
    The front affects the rear. Once your on the gas is all rear ....So have Mike set up the rear also..
    My 2¢
     
  6. DmanSlam

    DmanSlam Well-Known Member

    @rice r0cket:

    Sometimes I did but, apparently, not regularly. I neglected to mention that, on that weekend, that was my first time ever running slicks and it was a last-minute decision to do so. Guess I'll read up more on taking care of slicks. Not sure if 1.5 days use out of slicks seems right. But I'm comparing to DOTs with which I get 3-4 days out of.
     
  7. DmanSlam

    DmanSlam Well-Known Member

    Hey Mike. Yes, you were the vendor and I appreciated your service (I used your services a few times last year but first time for slicks). I think my issue is user error or bike setup.
     
  8. DmanSlam

    DmanSlam Well-Known Member

    @metricdevilmoto , I was running off of shore power that day. I also have a 4300, very-loud generator with about 60 hours on it. But didn't use it that weekend.
     
  9. DmanSlam

    DmanSlam Well-Known Member

    I believe I used my pit posse tire warmers. Possibly my svracing set.
     
  10. 2blueYam

    2blueYam Track Day Addict

    Looks like opening radius turns 2 and 9 chewing up the shoulder of the tire. I saw some wear like that on my 03 R1 on my Pirelli SC2 slicks on fast opening radius corners.

    Solution for me was in turn 2 is stay more inside and patient on the throttle. Finish the turn earlier then stand it upright and then finish the roll open of the throttle.

    Similar thing happened to me at Pitt Race. Same solution, but this time is was turn 5/6 where I needed more patience.

    None of this may apply to your 600.
     
  11. DmanSlam

    DmanSlam Well-Known Member

    Interesting that you mention those turns because I get on the throttle hard while tracking out through the exit portion of the turn. I didn't use to do that but the grip of the slicks 'allow' me more throttle application. I absolutely love that I don't have to wait until I finish the turn. Is my technique incorrect? Prior to doing so, other riders were walking past me on both sides.
     
  12. JCW

    JCW Well-Known Member

    Whenever I see excessive wear like that way off the edge of the tire, I think of cold tearing the tire under power. I had that kind of wear when my rear was set too high. Swingarm angle was too great and I didn’t get weight to transfer to the rear. As you stand the bike up and get on the power, the rear spins slightly overheating and tearing the rubber. I reduced the shim under the rear shock mount a couple mm’s and the wear went away.
    I ate up a brand new tire in just a few slow ass trackday sessions. It happens quick and I couldn’t even feel it.

    here’s mine, on a 750
    CE0CEDDA-C858-4D89-86DA-2CB658D0D24E.jpeg

    ‘this can also happen when going to a larger diameter rear tire. Dave moss has a video about this very common thing if I recall correctly...
     
    Last edited: Mar 7, 2021
  13. DmanSlam

    DmanSlam Well-Known Member

    I was on a 180/60R17 (180/55R17 is stock size for my bike). I re-read the lifeatlean.com article again. Based on the characteristics of cold and hot tears, I should be able to dig my fingernail underneath and lift small chunks. But that's not the case. That's if I'm understanding correctly. So, @damiankelly may be correct and I should go ahead and get the rear suspension set up for me.
     
  14. JCW

    JCW Well-Known Member

    You could... or you could just drop the preload to the rear to set the rear lower and see yourself... as a temporary fix.
    This may be a dynamic setup issue you won't see statically.

    But I'm just an internet jockey... don't listen to me. Lol.
     
  15. Motofun352

    Motofun352 Well-Known Member

    Don't expect to get the same life out of slicks as you do out of DOTs unless you baby them....what would be the point of slicks in that case?
     
    DmanSlam likes this.
  16. 2blueYam

    2blueYam Track Day Addict

    Yep. You should only give up a tiny bit of performance by not getting into the throttle quite as hard. It will also allow you to stay in tighter through turn 2 and improve your line entry to turn 3. Turn 9, it pretty much is a balance of how fast you want to go vs how long you want the tire to last. Congratulations on being fast enough and having good enough feel to burn up a tire on the edge of the tire. It is fun place to be. Suspension improvements may allow you to keep the speed without burning up the tire. Work with a good suspension tuner at the track or be prepared to spend time experimenting.
     
  17. ScottieDucati

    ScottieDucati Hopeless Never-was.

    There is no weird wear at the edge of that tire. That wear is off the edge, it’s from throttle application. Pics are a bit hard to work with, but sure looks like a rebound issue to me.

    Try a faster rebound damping setting and add a bit of spring preload.

    Sent from my iPhone using Tapatalk
     
  18. Pneumatico Delle Vittorie

    Pneumatico Delle Vittorie Retired "Tire" Guy

    Ahh, no the correct question is what was the hot pressure before he went out and what was it when he came in?
     
    DmanSlam and Daniel06 like this.
  19. Daniel06

    Daniel06 Well-Known Member

    Best guess is geometry cold tear.
    I'd go in the direction of finding your diameters of the tires not based on the size. Find the spec diameter. If the pirelli is rear taller and the front is shorter, geo changed. Or vice versa. I'd look there first. Find actual difference and adjust ride height to account. If that doesn't fix, it could be your weather conditions creating the cold tear. If this is the case, tire pressure up or down would be where Id go. Usually tire wear is normal when just slapping a different brand on. Reading a tire and fixing wear was so fun to me when you can get it right.
     
  20. racepro171

    racepro171 to finish first, first you must finish!

    waiting to get on gas, then on it too hard, need to practice earlier and smoother throttle opening. possible suspension issues too but if your able to get a few days from a tire, prob not pushing hard enough for that to matter too much.
     

Share This Page