Tire exploded, any lessons?
 

I was enthusiastically flying down the tarmac hill and hit a not so large tree branch. Didn't even feel anything on my drop bars, though I have an old Manitou suspension fork.

It felt like the rear tire exploded. Under close inspection I found a clean cut on the tire and a smaller less clean on the inner tube.

Just curious what actually happened:

1. Did something cut through the tire or did the inner tube/tire explode from the hit
2. Would having a lower tire pressure help to avoid this?

Tires: Panaracer Slick GravelKing 27.5x1.9
Pressure: ~5 psi below the max specified
Length of the cut: 2.5-3cm
Speed on decent: 25-30mph

https://cimg5.ibsrv.net/gimg/bikefor...96b974274b.jpg

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It think you probably hit something that cut it. I'd expect a failure due to a flaw or even something like a way overinflated tire to be more of a tear in the outer layer of rubber.

I agree with Iride. That looks more like a cut. I've had tires explode and usually you'll see some of the cording in the rip. That looks too clean. It might just have been coincidence hitting the tree branch. Shame, looks like a relatively new tire.

Yes, looks like a cut. Do you have a photo of the inside of the tire at the cut?
I rarely see any reports of tires exploding. And those few are often a long, ragged split near the tire bead, with casing threads hanging loose.

That 27x1.9 is about 48 mm wide. Panaracer says max 50 psi.
Try 30 psi! It's way more comfortable and just as fast. (You might want to lower the pressure in stages over a couple of rides. Just to adapt to the new road feel. A jump from rock hard to flexing over rough surfaces might feel a bit weird at first.)

Yep. A cut. Probably not due to hitting the tree branch. Given the cleanness of the cut, I’d suspect glass. You probably ran over a bit of glass elsewhere and the tree branch it may have been enough to complete the rupture.

Unlikely. Tire pressure has little to do with flats from whatever the tire encounters.

^ This. Saved me some typing.


Lower tire pressure allows the tire to deform around a potentially puncturing object, but with that kind of cut, I doubt it would have mattered.

Keep in mind if the tire pressure is too low a pinch flat can occur if you hit a pothole or road debris. However, the photo does not look like a pinch flat. It looks like something cut a slit in the tire.

Agree with the above, you cut the tire but the damage was not enough for immediate failure, with the impact finishing the job.

As for lower pressure, the only "benefits" would have been softer bump on your butt at the expense of possibly denting the rim. Given the relative costs of rims (wheels) and tires, it's not wise to think about risking rims to save tires.

that tire looks relatively new. anyone have access to this bike besides you? like in an apartment bldg hall? I like to think the best of ppl but the slice might be sabotage & the tree strike was just enough of a jolt, to open it up. if not I guess it was a pretty significant object cuz that's a broad laceration. don't recall anyone writing about a tire exploding while riding. good thing it wasn't the front, eh?

so you're going 25-30 mph & the back tire explodes. what happened? sounds like nothing major, you just heard it, maybe felt it go flat & then slowed to a stop? no traffic around?

Yep, the tire has less than 200 miles on it. The bike is always either inside of my house or my garage, that's definitely not a sabotage.

Nothing major happened after the tire explodes. Just extra drag and extra noise from the airless tire. No traffic, just an abandoned field road. Getting uber to rescue was quite a challenge.
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Thank's to all. It feels better knowing that it was a cut and I didn't cause it by the "tarmac only" tire pressure. Now it's time to test SpeedKings RaceSport 27.5x2.2 on the same road. They also don't have the reputation of cut resistant tires, but they should roll fast. 😁

As a late-in-life arrival to road bikes, after the better part of 4 decades on MTBs, "max pressure -5 psi" seems awfully high, especially for 1.95"-2.1" tires.
I mean, 20-30 is just fine for rocks and roots on trail, but anything less than 50 psi on the road, and you're at risk of bending your rims?
​​​​​​The advantage of fat slicks is that you can run them at lower pressure an enjoy a plusher ride without a big penalty in rolling resistance. If you pump them up rock-hard, you might as well be on skinnies.
A Also at lower pressure, you have a lot more contact patch available, which pays off in more available grip; I just finished a 26" city bike build that's running 2.1" BMX tires, and it is remarkable at how confident the cornering is ; it doesn't get upset by mid-corner bumps or surface changes, and is surprisingly competent on hardpack and gravel, despite having minimal tread
https://cimg9.ibsrv.net/gimg/bikefor...957bbfa76.jpeg

Be thankful that it was the rear tire and not the front.

Sure does look like you ran over something pretty sharp.

Cheers

With what I always carry, that tire would have gotten my me home, no sweat.

I don't know if your tube could have been patched but I always carry two spares. A good pump. And at least a half dozen dollar bills. So - simply replace the tube after laying several bills over the cut laid in both directions. Pump up to near your usual pressure and ride home. No Uber, no big deal. (And when I got home, I would patch that tire with sailcloth glued in with contractor's contact cement, ie the stuff countertop laminates are glued down with. That sailcloth - from a sailmaker, not the JC Penny stuff.) Stuff the bills back in your wallet. Those repairs will go the life of the tire. One tube - $6. Sailcloth plus cement - $1? Can you better that with Uber?

I'm quite good at patching the tires in the field, I only carry patches, but not spares. The cut on the tube was about 1cm long, should'be the problem.

Unfortunately this was the first time for me to patch a tube under a heavy rain. The seal just didn't want to stay and keep the pressure. Water and glue? Not surprising, yet caught me unprepared.

Ironically, the patch made a good bonding overnight, I might reuse the tire tube or keep it as a spare.

Banknotes to patch the tire seems to be a good idea, thanks.
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I patch first and do not go to the spare tube(s) but there are times when weather makes patching hard (your case), cuts are too long or many, valves or valve stem joints fail, light's failing and I do not have a light, inner tube sleeves fail ... Patches cannot do all. More than one flat per ride happens. I came up riding outside local calling distances before cell phones and never had a willing partner I could call to bail me out. Being close to self-sufficient has been my mantra a long time.

​​​​​Permanently fixing the cut tire also seems to be a good idea, though my common sense tells me that there could be some risks.

Started a new thread, just to be sure.

https://www.bikeforums.net/bicycle-m...you-think.html

the cut tire is junk

life is too short to drink cheap beer and fix cut/junk tires

Mystery solved.
 

Cycled back to the accident place, found a few razor sharp stones on that section. I guess they fall off an agriculture or a construction vehicle. What are these?

Picked all of them to make the road safer for my commuting. On closer inspection one of them seems to be matching the cut on the tire.

Mystery solved.

https://cimg7.ibsrv.net/gimg/bikefor...01d02279df.jpg
https://cimg8.ibsrv.net/gimg/bikefor...34d409da7d.jpg
https://cimg9.ibsrv.net/gimg/bikefor...40810cfec3.jpg

don't you think you would have felt striking something like that? dunno, looks like flint stone
https://cimg6.ibsrv.net/gimg/bikefor...e06a19a7c7.jpg

maybe a mix of granite & quartz? what state are you in? what kinds of quarries are in operation?

Yep, almost the exact same thing happened to me this past July. It’s easy to not feel hitting a small sharp rock when the tire is rapidly deflating. Same looking clean cut across the tire as mine too.

Agree with t2p.

Unless you absolutely cannot afford to replace the tire, I'd also recommend junking it. Too many cord threads are cut for me to trust it. I'd worry about the damaged cords shifting/pulling within the case and creating a new weak spot - and a new flat in the future. Worst-case it could blow when you're in a hard curve, causing your rear wheel to skid uncontrollably and putting you on the ground.

don't fix the tire. That's way too much damage. Besides, you'll feel the fix while riding thump thump thump...

I thought I hit a fallen tree branch, there is plenty of these laying around that road. Maybe I hit both, can't tell, but the shape of the surface of one of the stones matched the size and the profile of the cut.

Googled "flint stone", I think you nailed it, definitely look like it. No idea where they came from but according to the wiki flint stone was used in Southern parts of the UK to build churches, farms, houses etc. Still plenty of these Middle Age buildings in my area, perhaps somebody ordered these to repair their farm.

Thanks a lot.

my late Dad was a rock collector, so of course he dragged us kids along to some caves & such. it just looked familiar. I suppose you can test the pieces you collected, if you kept them

Thanks to all who replied. Despite of me getting emotionally attached to that tire it went to the bin. I really liked how slick Panarace GravelKing rolled, very smooth and supple, no rolling resistance and surprisingly great traction on tarmac especially while cornering.There is something magical about them.

Hope I will learn to love the new Continental Speed King II RS tires that I am trying now, still experimenting with the tire pressure.