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Discussion Starter · #1 · (Edited)
Hello,

This Pro 4 tire has cracking/dry rot ONLY at the valve stem area - both sides of the tire. I think pressure extruded near the valve stem from the narrow internal width of the Kinlin XR300 rim is the cause. Otherwise the tire is in good condition. It has happened to me twice now on a Pro 4. The tire has about 2K miles as a front tire in the past 16 months. Do I need to replace it?

Thanks in advance.
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User is infamous around
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I would. Will it hold? Probably, but why take the chance? Keep it as an emergency back up, then toss it when you buy another replacement for the other tire.
 

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Never Give Up!
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I would. Will it hold? Probably, but why take the chance? Keep it as an emergency back up, then toss it when you buy another replacement for the other tire.
^ This... not worth the risk
 

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If the front looks that bad, what does the rear look like? I'd pitch both and three Conti 4000s tires. Put two on your bike and keep the third for an emergency back up.
 

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That looks like some sort of abrasive damage to me. Did you have to fight the tire onto the rim or use irons or sum such? Is the bead seat of the rim clear of any sort of obstruction at that point?

I know that when I mount a tire, before I completely air it up, I will push the valve stem up into the tire to make sure that it is clear of the tire bead/bead seat so they are not fouled by the tube.

To ride or not ride that tire is your decision to make, but if you do ride it, I would recommend remounting the tire with an undamaged portion at the valve, and watch for any new or worsening damage.

What kind of air pressure are you running?
 

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Funny, this looks like something that could be posted in and moved to...guess which section?












Wheels/tires maybe?
 

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Discussion Starter · #9 ·
I would. Will it hold? Probably, but why take the chance? Keep it as an emergency back up, then toss it when you buy another replacement for the other tire.
Thanks for your comment. I replaced it.


If the front looks that bad, what does the rear look like? I'd pitch both and three Conti 4000s tires. Put two on your bike and keep the third for an emergency back up.
Rear is a different tire - it's a Pro 4 endurance and no issue.




Looks more like you hit something than rot to me. If it's not bulging it's probably okay but impossible to say.
Didn't hit anything. This happened with the previous set of Pro 4 service course, exact same spot.


That looks like some sort of abrasive damage to me. Did you have to fight the tire onto the rim or use irons or sum such? Is the bead seat of the rim clear of any sort of obstruction at that point?

I know that when I mount a tire, before I completely air it up, I will push the valve stem up into the tire to make sure that it is clear of the tire bead/bead seat so they are not fouled by the tube.

To ride or not ride that tire is your decision to make, but if you do ride it, I would recommend remounting the tire with an undamaged portion at the valve, and watch for any new or worsening damage.

What kind of air pressure are you running?
Yes, I used a lever to get it on the Kinlin XR300 but no issues mounting. I run 105 in the rear and 95 up front.


Funny, this looks like something that could be posted in and moved to...guess which section?

Wheels/tires maybe?
My bad.
 

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That looks like some sort of abrasive damage to me. Did you have to fight the tire onto the rim or use irons or sum such? Is the bead seat of the rim clear of any sort of obstruction at that point?

I know that when I mount a tire, before I completely air it up, I will push the valve stem up into the tire to make sure that it is clear of the tire bead/bead seat so they are not fouled by the tube.

To ride or not ride that tire is your decision to make, but if you do ride it, I would recommend remounting the tire with an undamaged portion at the valve, and watch for any new or worsening damage.

What kind of air pressure are you running?
Sure looks like the valve stem could be causing that little "hump" evidenced by the bead tear. Be sure to push the valve stem in before airing up next tire fully.
 

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Pressure's going to be the same all around the tire. As is the internal rim width at the bead. That does look like abrasion. Next time you have the tire off, inspect the rim in that area for sharp edges.

With 2k on the front on a Michelin PR you have used a good part of the tire's life, say 3/4. Tossing it at this point is only throwing away (cost of tire)/4.
 

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My pro 4's start to do that at the valve stem area so I just rotate them a few inches after a couple of months. I think it has to do with frequent pumping of tires and higher heat and humidity. My bikes are kept in an non AC/heated garage in the TX gulg coast area so temps and humidity can reach the 90's in the summer. I try to wear them out within a year anyway so I don't keep them more than 1
summer in the garage.
I know the off center label is not pro but I can live with it for a awhile.
 

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Pressure's going to be the same all around the tire. As is the internal rim width at the bead. That does look like abrasion. Next time you have the tire off, inspect the rim in that area for sharp edges.

With 2k on the front on a Michelin PR you have used a good part of the tire's life, say 3/4. Tossing it at this point is only throwing away (cost of tire)/4.
Ya have to watch it. 100 psi could work the wire looser on the sidewall and at a certain point, "Bam!" The tube bubbles out in the crack and explodes at the most inopportune moment, like scribing through a turn at 20 mph or sprinting to position yourself in the pack! :nono:

Don't ride on that tire. It's trashed.

When you put the new tire on, press the valve stem in to make sure its not stuck between the tire beads, before airing it up, just to be on the safe side. :D Tires are sneaky little basturds. Sometimes ya never know.
 

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Discussion Starter · #14 ·
My pro 4's start to do that at the valve stem area so I just rotate them a few inches after a couple of months. I think it has to do with frequent pumping of tires and higher heat and humidity.
So I am not the only person with this issue. Like you I also top off my tires before every ride, and I am also in a hot & humid area.
 

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Unsafe at any speed - REPLACE!

I agree that it looks like something abraded it. Possibly maladjusted brake pad?
 

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Riskier around the bead IMO. Conti GP4000SII tires always crack around the edge of the center track and I'm fine with that but I'd never risk cracking at the bead.
 
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