What does the "Set" button do?

[sambo]

Hi Sambo, Last Sunday I had a screw in my tyre and the ping went off on the dash. I stopped right away noticed a screw had gone in the tyre. Got the punture fixed 15 quid. Its as simple as that its never let me down before!! Brilliant little gadget IMO thanks Steve 

Hi Steve, sorry I didn't understand what you mean't in the previous post. What you are saying is that if you had driven around on it for much longer it would have goosed the tyre completly meaning a replacement tyre?

Do you have to cover a few miles before it goes off, or maybe just be travelling at the time? Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius. That being said I only drove a mile or 2 after to the nearest garage and pumped them back up to 31 psi. Will increase them to 35 psi once the snow has gone completely.

Sam

[Steve30]

Yes Sam . the first screw that went in I got it just in time before it went through the tyre!! I put a bit of washing up liquid over it to check if there was any air comimng out (none) It must tell you when there is a nail or screw in there? I'm on my 5th mk5GTI and its never let me down yet!! Hope ive explaned it a bit better steve30

[mac7]

Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius.

It uses the ABS sensors to detect a difference in wheels speed across each axle. If you'd kept one front tyre at 35psi and dropped the other to 26, it would have warned you.

[winrya]

they are very useful IMO.  Saved me a couple of months back on the m6.  It went off with me 20 miles from home, i presumed it was an error so reset it.  A few mins later it went off again.  As i was nearing a junction i came off, once pulled over there was a huge screw the size of a pound coin sat in my tyre with the air rushing out very quickly.  I hate to think what would have happened had i tried to get home at motorway speeds, I'd imagine a lot more hassle than a new tyre!!

[BuckieGTI]

I was told that they are sensors inside the wheels and not of the type that use the speed of each wheel to determine if the tyre is flat or not. Which is correct??

[topher]

Mine goes off with as little pressure drop as 2 or 3 psi.. bloody annoying! Must have something to do with the type of tyre.

[ub7rm]

I was told that they are sensors inside the wheels and not of the type that use the speed of each wheel to determine if the tyre is flat or not. Which is correct??

Its definately the el cheapo ABS system and not the sensor in the tyre version.

[Ed30DSG]

Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius.

It uses the ABS sensors to detect a difference in wheels speed across each axle. If you'd kept one front tyre at 35psi and dropped the other to 26, it would have warned you.

Is that really the case or was it that he had the ignition off when he let the pressure in the tyres down. I thought it might only detect a change in rolling radius whilst the system is active i.e. when the ignition is on?

I don't know the answer btw, just intersted in how it works.

[mac7]

Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius.

It uses the ABS sensors to detect a difference in wheels speed across each axle. If you'd kept one front tyre at 35psi and dropped the other to 26, it would have warned you.

Is that really the case or was it that he had the ignition off when he let the pressure in the tyres down. I thought it might only detect a change in rolling radius whilst the system is active i.e. when the ignition is on?

I don't know the answer btw, just intersted in how it works.

I'm pretty sure that if you deflate a tyre with the igntion switched off, it'll pick it up when you start rolling unless you've pressed the 'set' button. Have to admit though, I've never tried that!

[sambo]

Just to add seeingt as this thread had come up again. I let both out by hand so when I pumped them back up again one was at 26 psi the other was 23psi.

I'm pretty sure it will only detect a dropping rolling radius whilst it is being monitored (ie when the ignition is on) this is why people are saying it doesn't work very well I think. If you have a slow puncture and do many short journeys it probably doesn't register such a small drop on every trip as a fault . That seems to make sense to me anyway, looks like it can be quite a good system if you get a puncture on a long journey according to other peoples experiances, but then kind of defeats the object of having the set button in the first place?
 

Sam