Tyre Pressure?

[Rob3rt]

Pump them up higher than the minimum and as close to the max as suits your comfort level. If you arent attached to the fillings in your teeth, go for full pressure.

 

[HLaB]

If you arent attached to the fillings in your teeth, go for full pressure.

Have you seen their avatar

 

[Svendo]

Bear in mind some rims have pressure limits too, e.g american classic clinchers are limited to 120 psi: http://www.amclassic.com/documents/help/2009_edited/Rim_Tape_Strip_Tire_Pressure.pdf

 

[ClichéGuevara]

No.

The tyre’s volume is fixed and there are a fixed number of air molecules inside it, so according to the ideal gas equation the pressure won’t change (unless the temperature changes). Loading up a bike or car tyre does not change its volume to any measurable degree, so the pressure doesn’t change much either.

I'm sure you'll be right, I'm just struggling a bit with the thinking. I know that the air pressure holds the tire wall out and it's the wall that supports the weight, but I can't see how extra weight won't increase the pressure? If I keep adding weight, won't the tyre eventually burst? If so, what causes it to burst?

 

[gb155]

140 rear
120 front

I'm 16 1/2 stone though.

Ride road and footpath.

Bloody hell - I go 115 rear and 110 front these days and thought I was OTT, time to put some more in

 

[snailracer]

..the air pressure holds the tire wall out and it's the wall that supports the weight...

Not true for bike tyres which usually have very soft walls. Only slightly true for car tyres. Almost all the weight is supported by the air pressure acting through the contact patch, whose shape is constrained by the wheel rim. The bit of rim near the bottom flares out and applies more total force against that part of the tyre, and the increased reaction force at that part of the rim supports the weight (in simplified terms).

...If I keep adding weight, won't the tyre eventually burst? If so, what causes it to burst?

With enough weight, the rim pinching the tube/tyre against the ground causes the tyre to burst ("rim" or "snakebite" puncture) . Note that even "bottomed out", the rest of the tyre away from the contact patch is not deformed, therefore the volume of the tyre is not significantly changed.

I'm sure you'll be right, I'm just struggling a bit with the thinking...

Me too - every few years I get the pressure gauge out and measure the psi with me on and off the bike, just to check my sanity .