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Tire wear issue on Triumph 675 w/Pirelli, advice?

Discussion in 'General' started by desmo, May 31, 2012.

  1. desmo

    desmo Well-Known Member

    Just started running Pirelli this season on my 675, both the slick and DOT (Diablo Superbike and Supercorsa) have worn in this pattern with a defined trough between the edge and the middle of the tire and there have been huge issues with tearing both on cold and hot tracks. Anyone seen this before?

    [​IMG]
    http://www.flickr.com/photos/39272157@N07/7309366048/

    Only setup changes I made coming from Dunlop was to raise the front 4mm (partially for the taller rear and partially to get more trail per recommendation). Have tried various pressures from 24 up to 30psi hot, seems to end the same. Taking all the rebound out of the shock helps the tearing and wear a little, but makes the bike almost unrideable.

    Could this be a swingarm angle issue from the raised front? Is this a pressure or rebound issue? Wrong spring?

    I know I should be asking a suspension guy at the track, but have a race coming up and won't get any setup time beforehand, so any ideas are appreciated. I love the Pirelli front, but the rears are driving me nuts, hoping for a cure.
     
  2. ekraft84

    ekraft84 Registered User

    Sam -I'm not a suspension expert, but I would check what your front and rear sag numbers are at, as a start. Pirelli's are generally easy to get dialed in, so you shouldn't have to make any radical changes to make them work.

    Are you running the 180/60 rear? If so, those compared to the Dunlops are fairly close in sizing. They were a little different, but no major changes were needed if I recall. I'd make sure you're heat soaking the tire with the warmers for a good hour before going out also to ensure you're not cold tearing the tire. Check pressures before and after coming in in the first few sessions, if you're not already - to ensure they're staying consistent relative to the track temperature.

    It's definitely a bike issue to be sorted out. The Dunlops are a stiffer carcass tire compared to the Pirellis, so damping changes may help, but I would confirm you have the right spring on first.
     
  3. TakeItApart

    TakeItApart Oops!

    I have nothing all that great to offer, but I went from b-stone r10's to the us n-tec slicks and had the same wear. I had a 200 rear dunlop at Jennings. At Summit point, RTS sold me a 190 rear and the problem went away all on it's own. No setup changes at all.
     
  4. J Bart

    J Bart Fat Kid Track Days

  5. Mr Sunshine

    Mr Sunshine Banned

    Hum. My 675R with some massaging of the Ohlins shock with Pirelli's is wear beautiful! So its not the bike nor the tires.

    What compound are you running and what are the track temps?
     
  6. Daniel06

    Daniel06 Well-Known Member

    That's what my dunnies look like in the morning. Once the track warms it goes away.

    Drop the front and see if it cleans up in practice. If you have the angle too great, the bike wants to aggressively spin the tire, while the tire wants to grip. Seems logical to me.
    If dropping the front 4mm is not feasible, drop it 2 and lower the rear a little. Then reduce rear preload and see what happens.

    Thats just the direction I would go. Also, make sure the bike is still balanced rebound wise after its warmed up. The softer carcass may have you in a different portion of the stroke of the shock and forks. If its a familiar track, chk ur zip tie on the front compared to dunlops. It will tell u max stroke use compared to the dunlops.

    I'm not a susp guy. These are just some things to get you thinkin about.
     
  7. desmo

    desmo Well-Known Member

    The tearing was happening whether the track was hot or cold, and they were on warmers for at least an hour so I don't think it is simply cold tear. Hot pressures were kept around 29-30psi on this tire based on the Pirelli vendor and data sheet info. Pic is 180/60 DOT, ran 180/55 Diablo slick also and got the same type of wear. Last year was on 190 GP-A Dunlops and never had wear issues, and only setup change was really raising the front, same forks, shock, springs etc.

    My main concern is that in addition to the tearing it wears a concave groove in the "drive" area of the tire, literally I can feel a huge trough which may not be real visible in the pics.
     
  8. Daniel06

    Daniel06 Well-Known Member

    Which rear gpa? 190-55?
    Which front Dunlop? Gpa or gp?

    What's the difference in front tire height comparing Dunlop to Pirelli? You don't have to answer as long as you took it into consideration before raising the front.

    Is the bike doing anything different while you're riding? Is it spinning the rear pretty easily or is it the same compared to Dunlop?
     
  9. stangmx13

    stangmx13 Well-Known Member

    warmers dont prevent a tire from cold tearing. an over-inflated tire will still cool down and possibly tear even if u used warmers.

    if that is the correct hot pressure, u might want to verify the calibration of your gauge.

    ive torn tires in a similar manner from not enough rebound and/or not enough compression damping. i cant c how backing out the rebound all the way is ever a good idea. ive also torn tires similarly from having the front end too high. so, as u can prob tell, this could be any number of problems and my opinion is just an opinion.
     
  10. theJrod

    theJrod Well-Known Member

    One thing to keep in mind...

    Once the tearing has happened, any changes you make could actually "fix" the issue, but the tire won't look any better. So you may have already corrected the issue, but the tire is already too far gone to notice any improvement by looking at it.

    I'm running the same tires on my 750 - Still getting them dialed after switching from Ntecs. I've had some slightly excessive wear on both the 180/60 DOT and the 200/60 Slick, mostly when running the SC1 compound on a colder track. I'm still playing with pressures myself. The DOT has a super soft carcass, and I'm trying fairly low pressures which I think is contributing to a handling issue, so I'm working with my vendor to sort that out.

    Out of curiosity, what is everyone running for hot pressures on the new Pirellis?
     
  11. stangmx13

    stangmx13 Well-Known Member

    ive cleaned up 2 Dunlop rears before. one, i cold tore all the way to the edge on a drying track in the desert; took 4 session to clean-up at a later trackday. the other was a take-off from someone else that looked way wore than the OPs; it was perfect after 3 sessions.
     
    Last edited: May 31, 2012
  12. Pure Sportbikes

    Pure Sportbikes www.puresportbikes.com

    Try dropping your hot pressures before you go chasing suspension too much. 180/60 hot 25-27psi.

    It looks like cold tearing from over inflation. I've seen some fast guys run 23-24.

    What compound is it? The new SC1 is really soft and sensitive to track temps and tearing at abrasive tracks if your pressures are off.
     
  13. Pure Sportbikes

    Pure Sportbikes www.puresportbikes.com

    Also, I tore the shit out of a few sets of tires with a new gauge that I didn't see any reason to check, only to find out my new gauge was 6 psi low!
     
  14. Gorilla

    Gorilla Let me push on that bitch

    This.
     
  15. Harp

    Harp Well-Known Member

    Don't know the OP, so take this with a grain of salt....looks like a rider issue to me. Rolling through the corners on the edge, lifting the bike into comfort zone and hammering the throttle. Solution: earlier, smoother throttle application.
     
  16. :stupid:

    It could be a geometry issue. I ran a Slick front and DOT rear on my 675 because i couldnt get the geometry right with the Slick rear. I had excellent wear with a DOT but would tear the shit out of a Slick.
     
  17. motojoe_23

    motojoe_23 The Nephew

    IF changing hot pressures does not work, and since taking out rebound did not work, id say take out pre-load, or go with a one rate stiffer spring and take out a lot of preload. Both of those things have helped me in the past.

    If it is not just "cold tear" where a pressure change might fix it, and taking out rebound didnt fix it, then it may be spring tear where basically the tire is having to act as your spring. That is how I understand it anyway. I only know enough about suspension to get the basic jist though, and call Brian Livengood when I need a lot of help at Livengood Motorsports.
     
  18. Mr Sunshine

    Mr Sunshine Banned

    26 hot on the warmers for a 27 hot off the track goal.
     
  19. Roger@Arroyo

    Roger@Arroyo Well-Known Member

    Too much or too little pressure will give them the same look from what I've seen lately. Nobody in our area runs them that high, 27 is pretty much spot on off the warmers set to 180.

    Anyone running under 26 is either throwing the tire away after a couple laps or putting up with a greasy feel after a couple laps. 23 on a rear Pirelli.....possibly on a really light bike that's not working the tire hard, of course it'll feel like you're riding on a flat tire.
     
  20. motojoe_23

    motojoe_23 The Nephew



    Maybe your pavement is differnet out there (I had more tire issues at Miller than I have ever had in all the years I have on track combined) but I regularly run 25psi off the warmers set to 180ish and have not had any of the issues you speak of, on a 600, at a pretty respectable pace.

    I have gone as high as 27, but that is about as high as I have gone on the rear.

    Front 31-32 off the warmers.
     

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