tire cracks- Mtbr.com
Results 1 to 11 of 11

Thread: tire cracks

  1. #1
    mtbr member
    Reputation: masterofnone's Avatar
    Join Date
    Jun 2009
    Posts
    1,239

    tire cracks

    I've got cracks that have developed around the lugs on my rear tire riding in the snow and ice. The cracks spread between each other down to the carcass and the side knobs are tearing.It's high roller 2.7 downhill casing about 3 years old that wore just enough to keep as a spare.I've never come across this before, does anyone know if downhill tires are more susceptible to this kind of wear in winter temps or is this an isolated situation?

  2. #2
    Fatback
    Reputation: thirstywork's Avatar
    Join Date
    Dec 2006
    Posts
    705
    My guess is the durometer of the rubber is too hard for winter use. I have tried some downhill tires in the past, and they were hard as a rock at 20 degrees. Easy to see them cracking when they are brittle like that.
    Speedway Cycles owner http://fatbackbikes.com

  3. #3
    is buachail foighneach me
    Reputation: sean salach's Avatar
    Join Date
    Sep 2007
    Posts
    6,589
    The softer the rubber, the worse it is for the cold: <a href="https://www.flickr.com/photos/[email protected]/3264510013/" title="michelin cracks by anrothardonn, on Flickr"><img src="https://farm4.static.flickr.com/3534/3264510013_49fb7c248e.jpg" width="500" height="375" alt="michelin cracks" /></a>

  4. #4
    mtbr member
    Reputation: masterofnone's Avatar
    Join Date
    Jun 2009
    Posts
    1,239
    They are the 42 duro compound. I'm thinking just like old car tires they'll crack from non use, time to recycle it I guess. My theory is a downhill tire is designed to handle low pressures over a single ply without the beads or sidewalls disintegrating to better match the endo in front. I've experienced beads torn off the tire casing in the past, blasting slime all over the beach. Luckily I didn't "slime" any bikini babes I cannot squeeze larger than 2.7ish. Any recommendations?

  5. #5
    mtbr member
    Reputation: masterofnone's Avatar
    Join Date
    Jun 2009
    Posts
    1,239
    Thanks SS, I remember your pic and entry on this but couldn't find it.

  6. #6
    Muskoka
    Reputation: BlackCanoeDog's Avatar
    Join Date
    Jul 2003
    Posts
    3,433
    Yes, the photos show cracking that is typical of low temperature stress cracking in rubber. You were probably riding in temps below what the tire rubber was compounded for, no doubt aggravated by running low pressure for snow riding? The age of the tire would be a contributing factor also.
    https://get.google.com/albumarchive/...127?source=pwa

    RSD Bikes "The Mayor"
    Rocky Mountain Sherpa Overland

  7. #7
    mtbr member
    Reputation: masterofnone's Avatar
    Join Date
    Jun 2009
    Posts
    1,239
    The temps ranged from 20 to 5 degrees when I noticed the cracking appearing, running pressures around 15ish over frozen snow and ice, occasionally crossing through icy water. The carcass is pretty tough and I'm not worried about a blowout (I hope), but I'm gonna throw a freeride tire on close to the same size but harder compound and see how it goes.

  8. #8
    is buachail foighneach me
    Reputation: sean salach's Avatar
    Join Date
    Sep 2007
    Posts
    6,589
    The carcass should still be fine. I'm still running that tire in the spring, and running it tubeless, so it's plenty durable.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Jun 2008
    Posts
    1,193
    It is because of depletion of the ozone layer! You will see more cracks in the future..

  10. #10
    Muskoka
    Reputation: BlackCanoeDog's Avatar
    Join Date
    Jul 2003
    Posts
    3,433
    Quote Originally Posted by Yogii
    It is because of depletion of the ozone layer! You will see more cracks in the future..
    Ahhh...no! less ozone would infer less ozone induced cracking. however Tropospheric ozone on the other hand is the common source of pollutant and attacks rubber among other things. This is typically overcome by adding waxes to the compound, wax blooms out and protects the rubber. But that tire appears to have stress induced cracks typical of low temp and under inflation. Ozone induced cracking in rubber doesn't look like that. The tire tread rubber was never formulated for low temperature. note that the side walls are fine and even from appearances alone appear to be a different formulation. Cracking is not related to durometer hardness either, it is primarily dependant on the base polymer selected in the compound, some have good low temp properties ( natural and butadiene being two) and others do not
    https://get.google.com/albumarchive/...127?source=pwa

    RSD Bikes "The Mayor"
    Rocky Mountain Sherpa Overland

  11. #11
    is buachail foighneach me
    Reputation: sean salach's Avatar
    Join Date
    Sep 2007
    Posts
    6,589
    Not disagreeing here at all, but that tire was never really ridden in what I would consider really cold temps. At the coldest, we're talking -7F. Even in the upper 20'sF though, The tire became noticeably hard and slippery compared to other tires. It's the only one I've had crack at low temps.

    The cracking does all occur directly outward from a visible seam in the tire, but also happens to fall exactly where the tire experiences the most extreme bend when riding at lower pressures. So it could be two different compounds, or that the cracking in the highly stressed area was halted by the seam. Either way, you shouldn't use the Michelin 2.8" downhill tires in cold climates.

Members who have read this thread: 0

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2019 VerticalScope Inc. All rights reserved.