Can tyres pop if it's too hot?

Left my bike out in the back garden. Went to move it last night and the front tyre was flat with Stan’s jizz all the way around the rim of the wheel. Temps have been 36c ish in the shade so more in the direct sun. Just wondered why as it doesn’t appear to be a puncture but more an explosion. The other possibility was the dog chewed it but I can’t see any bite markes or holes anywhere. Weird!

from my vague recollection of thermodynamics and some google (including back to here to estimate the volume of a 2.3″ tyre on a 26″ wheel is about 5.8l. Not really going from 35 to 55 (unless I have ballsed up badly) wont do that much.

(P1*V1)/T1 = (P2*V2)/T2

Just need to remember the units to use…

I doubt it, from my vaguely remembered school science. Hopefully someone who can do the maths can demonstrate why.

Presumably we’re thinking that more heat causes the air constrained within the tyre to expand creating more pressure? My assumption would be that the pressure difference would be too minimal unless you’re running beyond max pressures which seems unlikely with a tubeless set up.

Edit: It seems mike had the same idea as I was writing.

Yeah did think it was unlikely but was the only explanation I could reasonably come up with.

Only had about 30psi in so I guess there must have been a leak/cut just strange to have sealant all around the wheel.

I have had road tyres go bang in the car on a hot day ,a tandem tyre go bang on a long descent under braking and a road tyre go pop on L`eroica in the heat .but not an mtb tyre

What kind of rim tape / strip did it have? Sounds like it might have let go, and the jizz went out through the spoke holes?

Packrafts are affected by heat a lot. When you pump them up with air, you have to ‘temper’ them with cold water, and then top up, otherwise the air inside cools and contracts, and the boat visibly looses pressure. Likewise, there was a problem with the seat backs bursting if left in the sun.

Direct sunlight on a black surface can raise the heat considerably.

Was it a Schwalbe tyre ?

I’d say road tyres and rims are more susceptible given the higher pressures and lower air volume. They certainly let go sometimes. Inside a locked car on a hot day is a special case too. We’re probably all aware that the temperature can get so high that it can kill in a short time, so the effect on pressure could be considerable, especially with road wheels.

If left in a car that turns into an oven in the sun I can kind of understand it.

In 36c sun, not a chance.

Managed 70km mid week which according to my Garmin was 40c. No doubt the asphalt was hotter, I had no worries about my tyres exploding.

Similar thing last year. Hot day, tubeless tyre on the bike on the tow bar mounted rack. Went to take the bike off the rack and saw that stans was spouting out of a 2-3mm cut in the tyre that had obviously/probably been done the day before on the Marin. No amount of spinning and swearing would get it to seal, and ended up using a worm to fix it. That decided it didn’t want to heal properly either. We ended up tubing it to ride Penmachno. Wonder if stans struggles to seal or remain solid in high temperatures?

Like the theory about the rim tape letting go. That makes sense. It’s just 3 wraps of decent electrical tape so I guess in the heat (yeah 36 in the shade but it’s way hotter in direct sun and with black rims and tyres…) the tape gave up.

Thanks all. Case closed I reckon. Pub?

Not seen it mentioned, but regardless of pressure I suspect black rubber gets very hot in direct sunlight and softens somewhat, making it morr susceptable to popping off the rim, or opening up any small cuts abrasions or gashes that are already there.

I’d say it’s unlikely to have gone bang due to the pressure (although i have no science to back this up). However, over time and heat cycles rubber can “overcure” and become brittle. If they’re old tyres, then it’s a possibility they’ve just perished.

Nah new tyres and only out for a day or two.

I’ve had two road tires (back and front) let go on a 40C + day when the bike was left in the sun (went some time in the afternoon while we were on the beach). They were close to maximum pressure before the bike was (carelessly) left in the sun

was in a bike shop when there was a sudden and almighty bang. the bike in the shop window had fallen over. upon inspection the rim had exploded. or rather the tyre had exploded taking part of the rim with it. trekking type bike.

I’d say it can happen. Happened to a tyre on my Inbred when I was using it for commuting. Left in a bike shed at work on a hot day…

Badger?

I put a Bontrager tyre on a Stans rim and rode it for a week, generally under the shade of trees, with no problem.
Used it at the Erlestoke 12, starting at noon on a very hot day, and it popped off the rim while riding across a grass field in the early afternoon.

I’ve always assumed it was increased pressure caused by the heat of direct sunlight that caused it.

mikewsmith – Member
from my vague recollection of thermodynamics and some google (including back to here to estimate the volume of a 2.3″ tyre on a 26″ wheel is about 5.8l. Not really going from 35 to 55 (unless I have ballsed up badly) wont do that much.

(P1*V1)/T1 = (P2*V2)/T2

Just need to remember the units to use…

Back of the envelope calculation suggests that the pressure in a tyre at 30 psi would only increase by approximately 2psi for a 20C rise in temperature so not likely to be due to the heat expanding the air.

Note I assumed that the tyre would stay at a constant volume – as it would probably stretch thne teh pressure rise would be less

Not sure we have badgers here in Oz but cannot completely rule out the possibility of a stealth badger that snuck in under the radar. Boat badgers are the scourge of Australia.

I think it the most likely explanation. If you pumped them up in a cool garage, the pressure in direct sunlight can easily double (or more), I’ve seen track bikes parked out in the sun go off like a mmachine gun. Not seen it for mtb, but it is the same scenario, just at lower pressures.

The pressure absolutely cannot double in an MTB tyre in anything like reasonable conditions, you’d have to go from freezer to a hundred degrees for that to happen. The most likely culprits are rim tape or Stans sealant changing at high temp, my money is on rim tape.

The pressure hardly changes (Boyle’s law). However, the rubber will get softer, the steel bead will slacken off and this makes a blowout more likely. Rim brakes can heat the rim to well over 100C, probably 200C, and this can severely weaken an inner tube, but that’s a more testing case than just leaving a wheel in the sun.

Rim brakes can heat the rim to well over 100C, probably 200C, and this can severely weaken an inner tube, but that’s a more testing case than just leaving a wheel in the sun.

I’ve seen an MTB tyre come off a rim cos of this, long alpine descent with magura rim brakes, rim, heated up and the bead melted off the (day or two old) tyres. So the bead was still in the rim, but the tyre wasn’t! Bit of a brown trouser moment for the rider concerned.

i had my minion pop off the rim in the kitchen when the heating was on full whack one night. the bead wasnt up to much anyways as tyre was on way out, but the heat certainly contributed to it. proper shit it when it came off 😎

Had a tyre go bang (crack, actually) on a road bike that I had leant against a radiator.

Boyle’s law has got nothing to do with it.

… an experimental gas law which describes how the pressure of a gas tends to decrease as the volume of a gas increases. A modern statement of Boyle’s law is:

The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged within a closed system.

How about some real world findings:

ttp://www.tirerack.com/tires/tiretech/techpage.jsp?techid=73

We put some of these theories to the test at the Tire Rack. First, we mounted two tires on wheels. We let them sit overnight to equalize and stabilize their temperatures and pressures. The following morning we set them both to 35 psi. One tire and wheel was placed in the shade while the other was placed directly in the sun. We then monitored the ambient temperatures, tire temperatures and tire pressures through the day. As the day’s temperatures went from 67° to 85° Fahrenheit, the tire that was kept in the shade went from our starting pressure of 35 psi to a high of 36.5 psi. The tire that was placed in the sun and subject to the increase in ambient temperature plus the sun’s radiant heat went from our starting pressure of 35 psi to a high of 40 psi.

Cooling or heating air can considerably alter it’s pressure. Again, from my practical experience, pumping up a packraft with ambient temperature air so it is firm, will lead to it going soft in 10 or 20 minutes in water, due to the water being considerably cooler and sucking all the heat out. This means that a packraft needs ‘tempered’ by splashing it with water and adding more air before use.

Was it a Schwalbe tyre ?

Yes, I’ve had a couple just inexplicably pop off the rim, bead is broken after too. I know of others who have experienced this. No relation to heat though.