Tyre Pressure Monitoring Systems

[ARWadsworth]

I did have a valve fall off whilst crossing St Georges bridge in Doncaster.

Apologies to the 3000 people that were late for work that morning caused by the hold up whilst I swapped the wheel.

[fred]

How did it fail? "Fall off" sounds funny for something that's pulled through from the inside.

Previous abuse? Sabotage (ex g/f)?

Now I know why you don't have signage on your van :-)

[ARWadsworth]

The valve had literally split where it entered the wheel and the external part was missing.

I had done 25 miles that morning without problem and within a few metres of joining the bridge I thought "oh shit".

Probably just bad luck. I had not had the van long.

I was recognised. Two of the bastards that were going in the other direction phoned me up to laugh at me and offer help (you can do both).

[The Natural Philosopher]

Like the time I was hammering my spitfire round the lanes and thought 'Hmm steerings a bit stiffer than usual and hammered it home..'

It sheared the ungreased kingpin doing 7mph in front of the police station the next day...

[dennis]

The rubber ages. They are cheap. No they don't charge £1.50 where i have my tyres done.

[fred]

Nasty, you think steel core, what's going to touch that but it's not going to stop a split in the rubber and of course they do remove them by pulling them through from the outside.

"I'd love to help but you'll have it fixed by the time I get through the traffic jam"

[Dave Plowman]

I can't see the point. Tyres and rims etc in good condition keep their pressure for ages. If you have a 'slow puncture' or a tyre going down for other reasons get it fixed.

[Jules Richardson]

Maybe (assuming it is some kind of wireless setup, although I imagine it'd be the easiest and - in theory - most reliable way of doing it), but three years doesn't seem very long, and I wouldn't expect sensor battery life to otherwise be mileage-related (unless the sensors 'sleep' but are periodically awoken by the vehicle when in use, I suppose)

The wireless sensors are presumably very short range, so that when owners rotate tyres/wheels periodically the vehicle doesn't lose the plot (and I'm curious now as to whether my spare has a sensor too, or if they cut corners there :-) I don't think it's one of those 'donut' ones, but a proper wheel.

cheers

Jules

[Andy Burns]

After slicing the wider part off on the inside, surely?

[Roger Mills]

The problem with wide low-profile tyres is that you often *can't* feel when they're soft unless you're participating in high-g cornering. If you get a puncture and drive for a few miles before you realise, the tyre's a write-off. BTDTGTTS!

[John Williamson]

Not always. Most of the times I've watched them, they just screw the removal tool on and lever away.

[Andy Burns]

Must be the backstreet place I use then, they always seem to have a "knife" fashioned from a sharpened hacksaw blade with an insulation tape handle, then yank 'em out with pliers

[fred]

It's a while since I paid any attention but I thought they just pulled them out (from the outside) with a tire fitters' tool, combined high leverage pliers and hammer for tapping on weights (if not using stick ons), no cutting. Old memories are of valve being ripped out to get rapid deflation before breaking the bead. Maybe bead breakers were weedier then and needed the tyre deflated before popping the bead.

Last time my (local, small, trusted) guy left the valve in-situ and popped the bead w/o deflating. Valve was fine so we left it.

[McKevvy]

You could tell the difference between 30 and 32 lbs/in^2? you must be VERY in tune with your car.

McK

[Dave Liquorice]

I can certainly tell between 28 and 30, depends on the tyre and car of course. Mine are 255/55R18 not a thick rubber band wrapped around the rim. B-)

[Owain]

Apparently my father once had the steering wheel come off.

Owain

[The Natural Philosopher]

I used to be.

These days a couple of pounds is less then the variation from cold start to a brisk run.

[dennis]

See below.

It always has been.

You can get more variation than that between the sunny side and the other.

[Dave Liquorice]

I've never actually measured the tyre pressures immediatly after bowling down the motorway for a few hours. I think I will just for interest. Tyres probably get hotter with "spirited" driving along bendy roads though.

Anyone up to the gas laws and working out the final pressures starting at say 28psi and 30psi for the same temperature increase with constant volume and mass?

[Huge]

There's no "probably" about it. Tyres can and will melt under the appropriate stress.