POW! tubeless tire blow-off on pavement. now I'm afraid.

I'm not new to tubeless, been running tubeless on my bikes for years now different rims and tires on different bikes. Recently I picked up some skinny tires for the Redlands ride coming up. I've probably logged in 100+ miles with these before this happened. lucky for me, I was riding along flat pavement abut 15 mph when POW! Complete blow-off and instantaneous tire separation! I look down and see the front rim grinding along on the pavement WTF!!!?? I am SOOOOO fortunate this didn't happen 20 minutes earlier in the ride when I was screaming down a long steep pavement road at 40 mph. Got a tube in it and finished my ride, but now I am freaked out. It's in my head. I'm scared to let off the brakes and get up to speed.

I assume this is a bad tire. It does slip very effortlessly without tools onto the rim. Stans yellow tape run about 45 psi.

Tire: Vee Rubber V-12 29x1.95 http://www.jensonusa.com/Tires-and-Tubes/Vee-Rubber-V-12-Tire

Rim: Pacenti CL25 http://www.bikelugs.com/store/index.php?intCategoryID=33

 

what keeps the tire on is the air pressure that pushes the bead in the the bead channel on the rim. if the centrifugal force acting on the tire exceeds the tires bead/rim contact, it will eject. is the tire rated TLR?

I have no idea, but are mtb tubeless pressures rated for onroad speeds? did you check if the pressure may have been lower due to a leak or puncture.

when was the last time you check on the sealant? If the sealant was dry, mine dries out in 3-4 months, then a puncture on the descent would necessarily leak all the air out. the same puncture would blow a tube too.

 

WHOOOAAA! That could have been scary on a fast downhill. Like yourself, I have never had an issue going tubeless, but I have never used a tire that slipped on easily....that could likely be the issue.

 

I literally broke my wrist due to a tubless tire burp down a steep, luckily slower section. Still ate it and fractured my scaphoid, the messed up part is that im still running it tubless lol wtf. pretty sure i didnt screw down the valve all the way and was loosing pressure all ride. heard it and saw it burp.

 

there ya go. it dont take a rocket scientist to figure it out. i like it when my tires make me use a tire lever. i had a maxxis max lite once. it was super easy to pull over the rims by hand. and it was a pita to get mounted tubless.

 

hmmm.... I ordered two tires from jenson. I did find it weird that they came in separate boxes and different shipping times (must be different suppliers?) the rear is a 1.75. It is labeled as "sealant compatible" and rated 30-50 psi. The front that blew off on the other hand, it has all the same logos and looks the same, except it does not have the "sealant compatible" signature and it is rated 40-65 psi. I didn't notice that before.

Be careful what tires you mount up out there people. this could have been disastrous !

 

I know you are looking for a good rolling tire for the Strada Rossa....if you don't trust the remaining tire (I wouldn't), consider a Maxxis Icon. It's a fast rolling tire, lightweight, and surprisingly good traction when tubeless.

 

I'd also be a little leery of a tubeless tire that goes on super easy and it would make me wonder if it was molded a touch too big, it stretched somehow, or the rims measures a touch too small at the outer bead area mating surfaces. The air pressure is what secures it to the rim so the bead design on the tire and the receiving area on the rim could also play a part if one was damaged or somehow not compatible.

You mentioned riding on flat pavement but do you recall riding over any small rocks or imperfections at the time it blew off? What's the recommended air pressure for that tire (can't pull up their site from the computer I'm on)? Did you see any large clumps of sealant on any portion of the bead or outer sidewall where it initially blew out at to maybe indicate too much sealant between the tire bead and rim indicating it might not have been seated fully?

I use my mountain bike out on the road quite a bit and have been thinking about trying tubeless to help traction off road by being able to run lower pressure, but I'd hate to have something like this happen at speed on the road or even in the dirt going downhill so I could definitely see your concern. If you're running the same tire front and rear maybe try switching them in case this one is prone to doing it again or maybe suck up the weight and run a tube up front and leave it tubeless in the rear.

EDIT: Just saw your latest post while I was typing this. Odd about the difference in markings and maybe you just got a bad tire.

 

Loose fit + 45 PSI = problem

 

Try to listen for the "double pop" noise as each side of the tire bead makes it's final snap into the outer profile of the rim during the initial inflation step.
If the tire beads doesn't make the "double pop" as it final seats, then chances are it's not a robust tubeless setup.
Also, maximum recommended air pressure FOR TUBELESS should be followed. Stan's ZTR rims have listed specs on this according to tire width.

Even if it costs a little more, try to get tires with TLR, 2Bliss (or equivalent tubeless ready) beads.
Cheaper than stitches.

 

sounds like a bad shipment.

glad you made it out with just a scare and not scars.

 

Edit looking at the rim me thinks the tire is not a good combo.

The rim is a " tubeless friendly design" and could be designed for UST tires. That is a miss-match.

Example Stan's and other bead hook rims work well with non UST tires.

UST tires should go with UST rims.

Hope that helps..

 

If you read the Stan's instructions, you'll see that they say NEVER go over 40 psi. You said you're running about 45 psi. "About" is the same as "I don't know because I didn't check it." Next time, check it.

 

hmmm, didn't know that. this goes for all tubeless tires and rims? Funny, the tire the blew is marked to be run 40-65psi and then the website for rims have little to no info about tubeless setup. I usually run much less pressure, but I didn't think 40-50 would be unsafe. The reason I say "about 45" is because that is was when I set them up according the gauge (unknown accuracy) and don't know how much air loss has occurred since.

 

The max 65 psi on the side of non tubeless tires is for use when running tubes. You can safely run a tubed tire at 55-60 psi. Tubed tires usually don't state the psi range for converted tubeless.

 

Rule of thumb: If the 10-year old girl with asthma can get the tire on the rim before inflation without using a lever, the tire's going to come off...tube or not. 1 in 10 tires I seat has this issue, from all manufacturers. Exchange it immediately. After my wife crashed with a front-tire burp, I checked it out and it was so loose that after reseating it, waiting a day, and throwing it up the in the air to bounce it, the bead blew off at 20 psi. Tire went on/off super easy without needing a lever or any effort. Same brand, new tire, PITA to get the bead over the rim, no issues.

Glad you're safe. Enjoy the Strada Rosa.

 

If the tire is NOT UST chances are it will blow off the rim , especially if it fits that loose
proper tires and rims ust compatible and you will be good

 

I just went down to the garage to confirm: On the back of the Stan's bottle it says that on mountain bike tires, never exceed 40 psi.

Don't feel too bad; you're not alone. Years ago while trying to seat a difficult tire, I blew it up and destroyed a rim. That's how I came to read the instructions on the bottle and learned not to over inflate.

 

How did the Stan's cause your rim to get destroyed? And how much pressure was in the tire when it blew?

 

When I first set up my tires tubeless, I am sure I read this and followed it when I seat the bead. When I read it today, I am definite I have forgotten it I no longer read instructions when I refresh my tires though. Not that I ever go over 30 anyway

Great reminder.