Can tires pop in hot car?

I cycle in the morning and most days my bike ends up inside my car all day baking in the Texas sun. I would assume that the temp in the car would go over 140 degrees on most summer days. I mentioned this to a freind of mine and he told me that he had heard of people having their tires pop because of the heat in the car. He thought I should bring my bike into my work place during the day, or at the very least let some air out of the tires.

Is this a real problem?

I have a Carbon bike as well, are there other issues with me leaving it inside the car through out the day?

Don't know about your frame - but I've heard people's tire popping up on their roof racks on hot days at races - so yeah I would think in the car the tires could pop easily.

I lost three sew-ups as a result of the tires overheating while they sat in the back of a parked SUV -- windows open ... dappled shade ... but there was apparently enough sun to superheat the rims due to lack of circulating air.

The solution: deflate the tires ...

Yes.

I have had at least two bike tires explode in the car.

I think a lot of those that explode were weakened tubes that would have given out after a few miles anyway, the heat just increased their pressure a little sooner to the breaking point, so I don't think it's a big problem



I doubt it's hot enough to be a problem with your frame.

Epoxy gets nice and soft with temperature... I probably wouldn't leave a carbon frame at those temperatures. If in doubt, contact the manufacturer.

John Swanson
www.bikephysics.com

Isn't carbon fibre a cross linked polymer and not a thermoplastic, hence no softening at elevated temp. ? tires... another issue...

Frames that use pre- preg carbon fiber are placed in an mold, it cost about $20k, before they are put in a high temperature oven. Framsets built this way, run about $4k to $5k. Anyway, I would be more concerned about my wheel bearing and free hub lubricant, at that temperature laying horizontal. But if you don't have oil on your trunk, it ain't leaking out,yet.

Nope. Carbon fiber is layers of woven nylon fabric (carbon fiber fabric) in a plastic/epoxy matrix.

John Swanson
www.bikephysics.com

I ride in the Palm Springs, Ca. desert. At a 130 degrees, the asphalt starts to melt in places. Since your rolling tire gets to road temperature, it's PSI has climbed way above what it was inflated to the night before or that morning. Any tire's maximum PSI, means just that. It doe's not mean inflation PSI.

I've heard that a extreme heat will deaden carbon fibre tennis racquets, so I would expect the same thing for a carbon bike frame. I would'nt take the risk.

This is only true to some resins. Thermoplastic resins soften when heates and harden when cooled. Thermoset resins have a much higher resistance to heat before they 'melt'. Most frames are built using thermoset, but if you are not sure, it would be better to stick on the safe side.

About popping tyres. Fully possible. If a bike is left, say, standing at a cafe on a really hot day, the tyres can pop if they are pumped enough. This occurred to a friend as he was drinking his coffee. He heard a *pop* hisssssssssss and looked around to see his bike riding an inch lower at the back. The answer to the problem is deflate them by 10-20 psi as they will 'refill' as they heat. Leave them very low if you are in a car.

Scuba cylinders can explode if left in a car boot,Taking into account the cylinder is pressurised enough that the extra expansion caused by the heat of the car pushes it passed tollerance.Charles's lawV1/T1=V2/T2
Same as a byicycle tube if it is pumped to the max your expansion tollerance is minimul,so if you expect hot days deflate those tyres.

CF tubing is a polymer/substrate matrix, but a thermoset, not a thermoplastic. Thermosets, once formed and cured, cannot be reformed into another shape by heat.
All the other goo is liable to melt and run.

__________________
BCaple oldguy
Trek 5200 + Ultegra
Santan Noventa (1988)
Vitus (1985)
Cannondale touring (1984)
Trek 720 (1982)

I live in Dallas and lost my almost new front tube between 1:30 and 4:30 in the back of my Explorer. Last week. I went to get the bike out of the car after my nap and DOH!

I don't think that law is the one you want, since you'll assume that the volume is constant. Better to use P1/T1=P2/T2 and rearrange to P1/P2=T1/T2 to see how the see the relationship between the temperature and pressure changes. Don't forget you have to change temperature units to absolute units, so, fer example if the temp in the car goes from 80 deg. F to 130 deg F, in terms of absolute temp (I'll use kelvin), that's a change from 300K to 328K, a change of only roughly 9%. The pressure will also change by 9%. Of course, the volume isn't really constant since the tires are getting hot and expanding some, and there are other complicating factors.