I recently bought two Pathfinder 42mm Pro tires for my rims (specs in the image). I had to buy each tire from a different shop. The one causing issues is from a local store. They only had one left, and they gave it to me without packaging. I ordered the other tire from an online shop, [and it looks different](https://i.imgur.com/RfUl5LH.png). The tire pressure for the TL setup was within the recommended limits. I was very lucky that the ‘explosion’ – there was a loud PENG! – didn’t happen while I was going downhill, which would have resulted in a hospital visit.
My bike mechanic was surprised and re-fitted the tire on the rim, letting the bike sit overnight. However, when he checked the next day, the tire had popped out of the rim again. Meanwhile, the other tire works as expected.
Does anyone have any idea why this is happening?
c0nsumer on
What pressure were you using? And how much do you weigh?
gravelpi on
Have you run other tires on these rims without issues? I would try swapping the tires to see if the issue follows the tire, or if it’s always on this one wheel.
Starfield00 on
Are you sure those rims are compatible with these tires
dano___ on
65 psi on a high volume tubeless tire is at the limit of what the system can handle. Wide rims increase the volume too, add in any inaccuracy from your pump, imperfect installation, or temperature changes and I’d say that the tire was just overinflated for what the system can handle.
Once a tire blows off once there’s a good chance the bead is wrecked, the second explosion proves that the tire is dead. Get a new tire, and use an online pressure tire calculation to find your ideal pressure, the max on the tire is just too high most of the time.
w1n5t0nM1k3y on
Have you actually measured the rims to verify that they are 25mm wide internally?
You mentioned in a response that you are running them at 65 PSI. Based on [this tire pressure calculator](https://silca.cc/en-ca/pages/pro-tire-pressure-calculator) even at 100 KG, it only recommends about 39 PSI. 65 sounds way too high.
grayden on
I had a pathfinder pro blow off its rim once, and I lost two other pathfinder pros due to bead separation. I love the tires but they just got too unreliable for me.
kixx05 on
Rims are not always perfect. Some carbon rims are so soft, they compress when the spokes are taut up to proper tension, and that makes the tyre go on the rim just by hand (basically the rim shrinks in diameter by a few fractions of a millimeter, or even more sometimes). That is not how a tubeless tyre should fit. If you install a tubeless tyre on your wheel/wheels and it seems too loose, there may be a chance for it to pop. I encountered all sorts of issues in my days as a bike wrench. I had all sorts of tyres pop off on all sorts of wheels. What makes a tyre pop? Bad fitment between it and the rim in most cases, like too loose a fit, too small a hooks, short sidewalls on hookless rims, not enough tubeless tape (yes, i had tyres pop at one pass of tape, but no issues at 2 passes), and so on.
Even the tyre can be bad itself … i’ve seen wobbly schwalbe expensive tyres, maxxis tyres with imperfect molds, continental with bad beads, and so on.
If a tyre pops on a tubeless setup, it’s usually toast, and can only be run with an inner tube from that point on, in my experience.
steezymtbrider on
Sometimes, tires and wheels just don’t go together. Even if they are both tubeless compatible, sometimes they just don’t cooperate. You can try adding a layer of tape to your rim bed, this could actually make it worse though.
MariachiArchery on
At 65 psi, you are literally right at the maximum. I’m not surprised this exploded. Specialized specs 65psi as the max here. Riding on that pressure will absolutely take it over the max. Temperature change could do it too. It could have even been just a bad pressure gauge telling you you were at 65psi.
You should never run tires at the max psi. Its just asking for trouble.
Now, regarding the blow off, once that happens once, the tire is toast. At this point, the bead is stretched out. *All* tire manufacturers will tell you this. If your tire blows off the rim, it ~~should~~ must be discarded. That is why this happened a second time, and, its going to keep happening unless you replace the tire.
Your best course of action here is to reach out to Specialized for a warranty claim. They might honor it. Aside from that, get some new tires.
Assuming a system weight of 100kg, I plugged your numbers into the SRAM tire pressure calculator and got:
Front Tire – 52.5Â psi
Rear Tire – 55.8Â psi
I know 10psi might not seem like a lot, but on these high volume tires, it is a lot. This is for gravel riding.
AbbottRacing on
Just to reinforce what others have mentioned, 60psi is WAY too much for that tire. The tire might say that is the max allowed psi but that doesn’t mean you should do it. Check the Silca tire pressure calculator for a more appropriate psi.
we-use-cookies327 on
I use these tires at 28 psi. 65 is mad
Aromatic_Pudding_234 on
There’s no point running wider tyres if you’re running them at those pressures. Anything over 45 psi is silly.
I run my 47s at 30psi for tarmac and even that feels rough on gravel.
Few-Horror7281 on
I am not going tubeless. Ever.
xoechz_ on
never had that happen to me while on tubes… i’ll get more and more scared of tubeless…
met a guy whose tyre popped right of the rim at 40 km/h in a corner going downhill… we talked at the workshop because i ruined two spokes at my backwheel and we were waiting for our bikes to be repaired… scary af
15 Comments
I recently bought two Pathfinder 42mm Pro tires for my rims (specs in the image). I had to buy each tire from a different shop. The one causing issues is from a local store. They only had one left, and they gave it to me without packaging. I ordered the other tire from an online shop, [and it looks different](https://i.imgur.com/RfUl5LH.png). The tire pressure for the TL setup was within the recommended limits. I was very lucky that the ‘explosion’ – there was a loud PENG! – didn’t happen while I was going downhill, which would have resulted in a hospital visit.
My bike mechanic was surprised and re-fitted the tire on the rim, letting the bike sit overnight. However, when he checked the next day, the tire had popped out of the rim again. Meanwhile, the other tire works as expected.
Does anyone have any idea why this is happening?
What pressure were you using? And how much do you weigh?
Have you run other tires on these rims without issues? I would try swapping the tires to see if the issue follows the tire, or if it’s always on this one wheel.
Are you sure those rims are compatible with these tires
65 psi on a high volume tubeless tire is at the limit of what the system can handle. Wide rims increase the volume too, add in any inaccuracy from your pump, imperfect installation, or temperature changes and I’d say that the tire was just overinflated for what the system can handle.
Once a tire blows off once there’s a good chance the bead is wrecked, the second explosion proves that the tire is dead. Get a new tire, and use an online pressure tire calculation to find your ideal pressure, the max on the tire is just too high most of the time.
Have you actually measured the rims to verify that they are 25mm wide internally?
You mentioned in a response that you are running them at 65 PSI. Based on [this tire pressure calculator](https://silca.cc/en-ca/pages/pro-tire-pressure-calculator) even at 100 KG, it only recommends about 39 PSI. 65 sounds way too high.
I had a pathfinder pro blow off its rim once, and I lost two other pathfinder pros due to bead separation. I love the tires but they just got too unreliable for me.
Rims are not always perfect. Some carbon rims are so soft, they compress when the spokes are taut up to proper tension, and that makes the tyre go on the rim just by hand (basically the rim shrinks in diameter by a few fractions of a millimeter, or even more sometimes). That is not how a tubeless tyre should fit. If you install a tubeless tyre on your wheel/wheels and it seems too loose, there may be a chance for it to pop. I encountered all sorts of issues in my days as a bike wrench. I had all sorts of tyres pop off on all sorts of wheels. What makes a tyre pop? Bad fitment between it and the rim in most cases, like too loose a fit, too small a hooks, short sidewalls on hookless rims, not enough tubeless tape (yes, i had tyres pop at one pass of tape, but no issues at 2 passes), and so on.
Even the tyre can be bad itself … i’ve seen wobbly schwalbe expensive tyres, maxxis tyres with imperfect molds, continental with bad beads, and so on.
If a tyre pops on a tubeless setup, it’s usually toast, and can only be run with an inner tube from that point on, in my experience.
Sometimes, tires and wheels just don’t go together. Even if they are both tubeless compatible, sometimes they just don’t cooperate. You can try adding a layer of tape to your rim bed, this could actually make it worse though.
At 65 psi, you are literally right at the maximum. I’m not surprised this exploded. Specialized specs 65psi as the max here. Riding on that pressure will absolutely take it over the max. Temperature change could do it too. It could have even been just a bad pressure gauge telling you you were at 65psi.
You should never run tires at the max psi. Its just asking for trouble.
Now, regarding the blow off, once that happens once, the tire is toast. At this point, the bead is stretched out. *All* tire manufacturers will tell you this. If your tire blows off the rim, it ~~should~~ must be discarded. That is why this happened a second time, and, its going to keep happening unless you replace the tire.
Your best course of action here is to reach out to Specialized for a warranty claim. They might honor it. Aside from that, get some new tires.
Assuming a system weight of 100kg, I plugged your numbers into the SRAM tire pressure calculator and got:
Front Tire – 52.5Â psi
Rear Tire – 55.8Â psi
I know 10psi might not seem like a lot, but on these high volume tires, it is a lot. This is for gravel riding.
Just to reinforce what others have mentioned, 60psi is WAY too much for that tire. The tire might say that is the max allowed psi but that doesn’t mean you should do it. Check the Silca tire pressure calculator for a more appropriate psi.
I use these tires at 28 psi. 65 is mad
There’s no point running wider tyres if you’re running them at those pressures. Anything over 45 psi is silly.
I run my 47s at 30psi for tarmac and even that feels rough on gravel.
I am not going tubeless. Ever.
never had that happen to me while on tubes… i’ll get more and more scared of tubeless…
met a guy whose tyre popped right of the rim at 40 km/h in a corner going downhill… we talked at the workshop because i ruined two spokes at my backwheel and we were waiting for our bikes to be repaired… scary af