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

Abnormal tire wear pattern?

Discussion in 'Tech' started by Thistle, Jun 21, 2018.

  1. Thistle

    Thistle Well-Known Member

    Seeking wisdom from the all-knowing beeb... I have a question regarding rear tire wear on my track/race bike. The attached images depict two different tires of the same brand (Dunlop KR451's). The first pic was taken following a track day, the second pic was taken following a race day - different tire. Pic number 3
    is a sketch showing the pattern - which you'll note is pretty localized.

    Is this an abnormal wear pattern?

    In both events the tire pressure was set to recommended values 22-25 psi. I monitored pressures throughout the day and adjusted according to ambient temperature.

    I'm a novice rider and wholehearted acknowledge that my skillset in setting up a bike for optimum geometry and suspension settings is limited at best, so I'm looking for a place to start. Can this be attributed more to suspension set up? To hard? Too soft? Rebound? Compression? Where do I start?

    Thanks in advance for your help.

    IMG_2284.JPG IMG_2539.JPG IMG_2540.JPG
     
  2. SPL170db

    SPL170db Trackday winner

    Cold tear? Pressure too high?

    You said 22-25, what is that? Cold starting pressure or hot off the track. Generally I start at 20 cold for Dunlop DOT and slicks and work from there depending on conditions.
     
    Thistle likes this.
  3. badmoon692008

    badmoon692008 Well-Known Member

    Without knowing the track, temps, pace, etc. anyone here is just going to be shooting in the dark. Suggest you talk to either the tire vendor or suspension guy at the track and ask their advice.

    That being said, I get very similar wear often and was told it was because I was too hamfisted getting on the gas coming off a corner.
     
    emry, HellrazoRR and Thistle like this.
  4. Thistle

    Thistle Well-Known Member

    I started with 25psi while on the warmers and by the end of the day (as the track temp went up) I went down to 20psi on the warmers. Granted, tire temp on the warmers wouldn't be as hot as 'on track' temp, so your suggestion of too high a pressure would probably be correct. Thanks man.
     
  5. Thistle

    Thistle Well-Known Member

    Yeah... I feared that would be the case. Maybe I'm looking for the proverbial 'smoking gun'... ;) . The track was UMC (aka Miller Motorsports Park) on the West configuration. 1:41 lap times - which probably won't mean much to many on here. There's some pretty knowledgeable folks down there so I'll ask them next round. Thanks!
     
    badmoon692008 likes this.
  6. RightSideUp

    RightSideUp Well-Known Member

    More of a suspension issue than a pressure issue going on there..
     
    5axis and Thistle like this.
  7. RightSideUp

    RightSideUp Well-Known Member

    Best to work with a suspension guy to get your baseline set up and tune from there. How many trackdays since the shock has been serviced?
     
    Thistle likes this.
  8. Thistle

    Thistle Well-Known Member

    Rear shock is a used Ohlins unit (not TTX) that came from the same bike as mine and a rider of similar weight. Its done 6+ trackdays and a couple of race weekends. Never been serviced... (embarrassed to admit)

    I've got some feelers out there to some of the guru's that frequent Miller. Thank you for your counsel - I agree; I'll work with them and get a baseline set up.
     
    Last edited: Jun 21, 2018
  9. emry

    emry Can you count? 50 Fucking what?

    This.

    I would wager that you are not carrying enough corner speed and your initial throttle pick up is late, once you start to stand the bike up you make up for that with lots of throttle. You can chase this with suspension but I don't think that isn't issue, if you spread that acceleration across a wider area of the tire, all of a sudden that localized wear will actually look like very good tire wear.
     
    Thistle and svracer22 like this.
  10. Your smoking gun needs to start with gathering better data with off the track temps as a start unless something is grossly odd with your suspension. You adjusted your warmer temps to ambient temps but didn’t see what effect they had on the application of those adjustments I e off the track temps. Temps are a guide but you can have 2 people, exact same everything on the track except riding styles and have a decent variance in tire temp.
    My point is, collect better data and work with a respected tuner. We went up almost 2 psi in a front tire in BSB last weekend which is a lot to add to a front but it was data driven and it worked for that track and conditions.
     
    Thistle likes this.
  11. stangmx13

    stangmx13 Well-Known Member

    UMC Outer will tear on the left until it gets rubbered in even in near perfect weather. I’m sure a lot of that is due to the T1, 3, & 4 which is on West iirc. An ez way to prevent that is going up in pressure to something like 25 off the warmers. But id never race on that high, just get through practice.

    With all that said, u are tearing both sides and have very little wear on the edge. So it’s hard to blame the track. I’d guess u are hamfisted w the throttle based on the little info we have.
     
    Thistle likes this.
  12. svracer22

    svracer22 Well-Known Member

    This.
     
  13. track wagon

    track wagon MCAS MIRAMAR

  14. track wagon

    track wagon MCAS MIRAMAR

    I had my rear at 27 at big willow to keep it from hot tearing.
     
    Thistle likes this.
  15. track wagon

    track wagon MCAS MIRAMAR

    Look how much rubber is on the edge.
     
    Thistle likes this.
  16. track wagon

    track wagon MCAS MIRAMAR

    Also the tears are more shallow cold tears are deep.
     
    Last edited: Jun 25, 2018
    Thistle likes this.
  17. Gino230

    Gino230 Well-Known Member

    What compound tire? What was the temp that day? FWIW a good suspension guy is worth their weight in gold- they are awesome for situations like this. Even if you are a novice, don't hesitate to ask them questions. You will learn some things along the way, too.
     
    Thistle likes this.
  18. MurfSVR

    MurfSVR Well-Known Member

    What does your front tire look like? Are you adding throttle without taking away lean angle aka doing a lot of mid corner acceleration?(that’s my guess). Typically when I see that kind of tearing and the pressures are good it’s because the rear is too soft, front is too hard, or you’re adding a bunch of throttle while maintaining lean angle. Many novice riders do this - it feels fast, but it’s not, and it tears your tires up.

    Edit: or just throw a Dunlop Med+ on there, you’ll have a hard time tearing those up lol

    Sent from my iPhone using Tapatalk
     
    track wagon and Thistle like this.
  19. Thistle

    Thistle Well-Known Member

    Firstly, I want to thank you guys for your collective knowledge and contributions - very much appreciated. Next time on track (for me) will be July 14/15 and I'll certainly be collecting data on track temps, tire pressures, tire temps etc, etc, etc...

    However, on a side note, I think my 'smoking gun' is me....

    Not to belabor this post, but some back ground on my track history; the last time I raced a bike was in 2014. Work commitments, and travel for same, saw me away from the sport until this year. After sharing my recent tire woes with my brother, he reminded me that this was not a new problem for me and then sent me the pic below. It is uncannily similar to what I'm experiencing of late... Only this was a Bridgestone mounted on a MV Augusta F3 that I raced in a one-off round in 2014. Remarkable coincidence?

    A number of you have commented on 'ham-fisted throttle hand' and 'adding too much throttle at lean' etc. The evidence would suggest that this is where the problem lies... In conjunction with taking a sh!tload of notes and collecting data, I'll also be cognizant of what my throttle hand is doing mid corner/exit of corner.

    Thanks again lads!
     

    Attached Files:

    badmoon692008 likes this.
  20. MurfSVR

    MurfSVR Well-Known Member

    Just think about it this way - if you are in the corner and feel like adding throttle, don’t, but next lap enter a little faster. Wait to add throttle until you can see your exit and take away lean angle while adding throttle. The trick is to make your entry so good that there’s little time between deceleration and acceleration.

    Basically, listen to Ken Hill’s podcasts all day everyday. KHCoaching.com


    Sent from my iPhone using Tapatalk
     
    Thistle likes this.

Share This Page