ViperZ

I've been riding on a set of Pirelli Velo Cinturato 700x35C all year and noticed the tire had blistered, bubbled during a post ride cleaning. I deflated and dismounted the tire, and the blister was also on the inside of the tire. There were 2 blisters, almost diametrically opposed, however I suspect that is coincidental. I cleaned up the tire and let it be, the blister remained until I checked it the next day and now they are pretty much gone. It seems like some of the some sort of pressure leak allowing air or sealant in-between the carcass liner and tread. I'm using Stan's Sealant, at a tire pressure of 55psi. What's strange is how these blister occurred at the same time 6 months into riding.

I have requested a warranty claim with Pirelli and Pro Bike Kit (seller) and will see where this goes. I'm not sure its worth the hassle of returning to the UK from Canada, and may just use the tire with a tube. More so I just want understand what happened and if anybody else has experienced this same problem? Google doesn't turn up a lot of current related results. However I did find one related with the same tire.

Thanks!

ViperZ

Update: I contacted Pirelli, they told me to contact my seller. In this case it was Probike Kit in the UK. I contacted them and they said the apologized for the inconvenience, and would refund me the price I paid for the tire, as they did not have anything in stock. Kudos to PBK for solving and resolving the situation with in a day of contact. They didn't ask me to send the tire back either.

I just would like to understand what is happening and why its blistering like this. I suspect the hole has to be microscopic in that its too small for sealant to get in and seal, yet large enough for air pressure to inflate slowly over time. I conclude this as I remounted the tire with sealent, and it did not blister right away, however after a few hours, its starting to bubble in the same spots again.

Surely I'm not the only one to see this occur with tubeless tires?

Iride01 

If curious, put a hole in the outer blister to let the air out from between the layers. Then ride it till it becomes worse, unless it's already causing issues.

Otherwise, probably some of the layers didn't vulcanize or get stuck together well and air got in there but couldn't fully escape before making the blister form.

At least that's my story... and I might not stick to it!

well biked

We've seen this happen, occasionally, over the years to tubeless tires. It's usually after they've had liquid sealant in them for a very long time, the sealant can cause delamination and casing breakdown. Not a chronic problem, but it does happen occasionally with some tire/sealant combos. This may be a case of the tire and that particular sealant not playing well together, or it might just be, purely, a defective tire. Either way, it sounds like the tire is being covered by warranty (via refund), and I think that's appropriate here.

Troul 

from the inner surface side, inject a vulcanizing tire cement for each of the blistering areas to fill the void once the blisters are no longer protruding. Let it cure & it could last a while.

ViperZ

I so wanted to do this or even puncture the tire and see how the sealant fixed it up...


I'm using Stan's sealant, and its been about 5 months with it. Yes I'm happy it's covered under warranty, however I now gun shy as I'm worried this may happen to the rest of them. I also have there mounted on my wife's bike I also really like these tires in the 35mm size and currently no other manufacturers seem to make a slick like this in the 35mm size. I ran the blistered tire with a tube in it yesterday, no issues so far, time will tell....

Not a bad Idea... I was wondering where the air pressure is entering to create the blister... Doing more searching it seems this can be a problem for these Cinturato tires, and I should just run them tubed to prevent this. Not idea, but hey we've been running tubes since forever