Tyre pressures and the cold

[chris-s]

Such a nice morning I decided to ride to work, retreived the bike from the garage (~3 degrees C) and the tyre pressures were down around 60-70 psi so pumped them up to 120 as normal. The bike is now sat in the office and I suddenly thought 'are the tyres going to go bang' now it's in a warmer environment?

Chris

 

[CanucksTraveller]

Shouldn't have thought it would cause any significant problems... physics is a distant memory but I don't think there is a huge pressure differential between the temperatures we're talking about. It will differ, but not nearly enough to blow your tyre off.

 

[SquareDaff]

Physics is a long distant memory for me too....but isn't pressure/volume/temerature calculated on the Kelvin scale?!?! There's little difference between 275K (2C) and 295K (22C) in terms of ratios - you should be fine.

 

[zoxed]

My quick Google gave me: http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=73 which states, as a rule of thumb, 1 PSI per 10 deg F, so an 80 degree change would be 8 PSI. Possibly noticeable, but I think would not account for your loss of pressure, nor would it (probably !!) cause an explosion.

 

[CanucksTraveller]

An average change of about 7 or 8 PSI then, assuming a moderately warm room (22 Celcius) versus a cold outside road (1-2 celcius).

I'm not even sure I'd notice that on a road bike.

 

[Norm]

An average change of about 7 or 8 PSI then, assuming a moderately warm room (22 Celcius) versus a cold outside road (1-2 celcius).

If the figures zoxed posted are correct, then moderately warm (and I'd call 22 celsius pretty bloody hot!) to cold is only a change of 35°F or about 3.5psi.

To make the pressure change by 8psi needs a temperature change of 45° celsius, which is quite a lot.

 

[CanucksTraveller]

You sure? 20 degrees C is 68 degrees F.

(Either way, no rubber is going bang here I feel).

 

[Norm]

You sure? 20 degrees C is 68 degrees F.

Very sure.

A temperature of 20°C is the same as a temperature of 68°F.

However, that's not the same as saying a temperature change of 20°C is the same as a temperature change of 68°F.

0°C is 32°F.

 

[CanucksTraveller]

Oh yeah. Back to school for me.

 

[potsy]

If the figures zoxed posted are correct, then moderately warm (and I'd call 22 celsius pretty bloody hot!) to cold is only a change of 35°F or about 3.5psi.

To make the pressure change by 8psi needs a temperature change of 45° celsius, which is quite a lot.

Very sure.

A temperature of 20°C is the same as a temperature of 68°F.

However, that's not the same as saying a temperature change of 20°C is the same as a temperature change of 68°F.

0°C is 32°F.

You are Mumbo Jimbo and I claim my £5

 

[Norm]

Rumbled.

 

[Dan B]

I did once have a tyre go bang when left outside in the warm, but I think that was the effect of direct sunlight on it not just ambient temperature

100psi is about 7 or 8 atmospheres, iirc. Any changes in atmospheric pressure that are going to affect your tyres, I reckon they're going to affect your lungs first ...

 

[youngoldbloke]

- maybe not park it next to a radiator ........ ?

 

[andrew_s]

SquareDaff is correct.
The pressure after warming up in the office would have been (approx) 120*295/275 = 129psi

 

[buggi]

aren't you supposed to measure tyre pressure when it's cold anyway? i know you do for cars.