Weird pink dots on my tires, what is this?

Everything about building wheels, glueing tubs, etc.
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superdx
Posts: 507
Joined: Sun Jun 29, 2014 1:27 pm

by superdx

Image

I tried wiping it away (and it does come off after some scrubbing), and I can see that the tread is wearing away under the rubber.

Is this some kind of fungus eating my tires?!

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F45
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Joined: Wed Jun 08, 2011 6:08 am

by F45

Looks like tubeless sealant weeping.

by Weenie


Butcher
Shop Owner
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Joined: Sun Jan 03, 2010 4:58 am

by Butcher

Yes it does.

superdx
Posts: 507
Joined: Sun Jun 29, 2014 1:27 pm

by superdx

Hmm, but I don't use sealant on these. They're just normal carbon clinchers

11.4
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Joined: Tue May 23, 2006 4:33 am

by 11.4

That's not sealant coming out. The photo is slightly fuzzy but it looks like either the wheel was leaned against something that the color transferred from, or the tire was abraded slightly and a little color is showing through. I'm guessing the former, but needs better photos to be sure.

TheKaiser
Posts: 436
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

That is weird...I would have guessed sealant too, but since that is ruled out...

Does the color go all the way around the circumferance of the sidewall?

If the wheel was just leaning against something like 11.4 said, you wouldn't expect it to go all the way around. If you rubbed against something while riding, like the side of a painted curb, that could make it go all the way around though.

Does it appear on both sides of the wheel, and does it appear on front and rear wheels?

I've seen fungus growing on tires stored in moist environs before, but it has always been a whitish color and more thin and dusty looking. Having said that, there are a lot of different fungi in this world. This really seems to follow the fabric patterns of the casing plys quite closely.

Have the tires been exposed to any sort of solvents (bike cleaning, or perhaps a puddle on the garage floor) or high heat (parking next to a heater in the house, hot car in summer, etc...)?

Some tires have other color base rubbers used in the construction, that then get covered by black rubber later. If that base rubber was decomposing it might kind of bleed through.

What is the texture of that pink stuff? Soft and mushy? Firm and rubbery? Hard and crunchy?

steelbikerider
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Joined: Sat May 07, 2016 11:31 pm

by steelbikerider

If they are Michelins PRO4's, it is a layer underneath the top black layer of rubber. On mine, the pink seems to ooze thru especially on the sidewall where the tire has been rubbed against something. It doesn't seem to do any long term damage but it did seem to happen more in hot weather. My bikes are stored in the garage and in the summer heat and humidity, more pink showed up. My tires only last about 4-6 months so I wasn't too worried. I did have some older worn tires that had been in the garage for more than 2 summers that I threw out when the casings started to deteriorate and the pink goo was all over the sidewalls . I'm slowly switching over to Contis but I still have almost 2 years worth of PRO4 endurance tires for training. I keep them in the house now unless they are on the bike.

superdx
Posts: 507
Joined: Sun Jun 29, 2014 1:27 pm

by superdx

Yeah Pro4 Endurance. Here's a video... when I rub off the pink stuff it looks like the outer rubber is being eaten away slightly. And yeah it gets crazy hot and humid where I am.

https://www.youtube.com/watch?v=uXHwKSW ... e=youtu.be

TheKaiser
Posts: 436
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

Well that sounds like the answer...Michelin's pink casing layer, combined with hot humid weather, combined with a little sidewall wear or abrasion. Case closed!

superdx
Posts: 507
Joined: Sun Jun 29, 2014 1:27 pm

by superdx

I'm actually still confused lol, what's happening? The pink casing is melting and just leaking through? There's more of it coming out every week (I don't ride this bike often), but the bike is stored inside where there's AC. I do ride in hot & humid weather though.

11.4
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Joined: Tue May 23, 2006 4:33 am

by 11.4

I called around because I was incurably curious about this one, and heard that Michelin had told some people that the pink was the undercoat sealant applied to the sidewalls before the black finish is topcoat. Michelin sprays the undercoat on and if they don't get it right, there's too much. It isn't about heating per se, because the tire gets a heat treatment after the black goes on, but just a matter of whether the spray orifice clogs and the pink comes out more in spatters or a narrow line rather than a thin even coat. If there's too much of it piled up, it shows up this way. I don't have direct verification but it sounds reasonable. And it is not common (runs in small batches that aren't that evident during manufacturing, so QC doesn't catch them) and it doesn't affect actual performance.

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Calnago
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Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

I'd want an exchange regardless of whether it affects performance or not. Who wants pink bubbles oozing from their black tires.

peted76
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Joined: Mon Jun 23, 2014 10:30 pm

by peted76

Calnago wrote:I'd want an exchange regardless of whether it affects performance or not. Who wants pink bubbles oozing from their black tires.


I know right.. now if they were blue...

uraqt
Posts: 810
Joined: Mon Apr 03, 2006 8:53 am

by uraqt

Mine just started doing this too, and I live on nor cal, and it's a rear wheel so it not a heat issue..

C

by Weenie


VforVonnegut
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Location: Ann Arbor, MI

by VforVonnegut

Aliens.

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