Tyre Pressure Sensors ? How does it work?

[rich146]

I want to change my alloys on my new Leon but something that struck me was the tyre pressure sensing. I have heard of sensors in the wheel but this was an aftermarket system on ebay. will I be able to change the alloys as normal? How does the tyre pressure system work? Cheers

 

[coggie]

The ABS sensors detect the speed at which the wheels turn, knowing therefore if they have stopped/locked up

Knowing the speed they can detect if one wheel is spinning faster than another, say if the tyre is deflated the overall circumference will be smaller - meaning that it will have to spin faster to keep up with the other wheels.

By pressing and holding the button by the handbrake you reset the system, should be good enough for changing wheels.


It's worth noting the system can't detech small changes in psi, it's more of a warning to people who never check tyre pressures.

 

[xmichaelx]

My tyre pressure sensor didnt alert me to a flat and when i questioned the dealer on this I was told that you have to drive a fair distance(a few miles) for it to kick in. Luckily I only drove a few minutes before realising but I was annoyed that the sensor didnt pick it up.

 

[predo]

My tyre pressure sensor didnt alert me to a flat and when i questioned the dealer on this I was told that you have to drive a fair distance(a few miles) for it to kick in. Luckily I only drove a few minutes before realising but I was annoyed that the sensor didnt pick it up.

thats quite on contrary to what I experienced. Picked up screw in tyre on Friday last week and got a ding almost immediately after it happened, I only managed to drive short distance away from home so it must have been somewhere between home and where I got ding from the car Pressure went down to 5psi and as it turned out tyre is unrepairable.. £120 notes went away... I didn't realise how expensive Bridgestone Potenza's are...

 

[coggie]

My tyre pressure sensor didnt alert me to a flat and when i questioned the dealer on this I was told that you have to drive a fair distance(a few miles) for it to kick in. Luckily I only drove a few minutes before realising but I was annoyed that the sensor didnt pick it up.

Aside from the fact you didn't get a warning, dealers arn't always the best for info.

I could and hope that I'm wrong but it sounds like there 'may' be a fault and the dealer was fobbing you off??? Like I say, I hope that not to be the case.

 

[calum001]

i've always wondered how these work/are fitted as i've seen a couple that have a screen that shows the exact psi of each tyre

 

[Fl@pper]

The ABS sensors detect the speed at which the wheels turn, knowing therefore if they have stopped/locked up

Knowing the speed they can detect if one wheel is spinning faster than another, say if the tyre is deflated the overall circumference will be smaller - meaning that it will have to spin faster to keep up with the other wheels.

what happens when you get wheelspin or go round corners ?

surely they will be using wireless wheel pressure sensors inside the tyre ? i know a lot of other latest VAG systems do.

Renault have been using em for years and i'm sure VAG are also using the french Beru designed ones too but a later version, they were always trouble in teh past so i hope they have nailed it now

 

[coggie]

It's all over a given time as far as I know, there was a post regarding people having the light come on when going round a long curve/bend in the road - can't find the thread now though.

It's not a sensor fitted on the wheel, or there would be lots of unhappy people with fault lights on after changing their wheels. Besides, if the car knew the actual psi, it would tell you like the renaults do.

 

[/dev/null]

what happens when you get wheelspin or go round corners ?

surely they will be using wireless wheel pressure sensors inside the tyre ? i know a lot of other latest VAG systems do.

Renault have been using em for years and i'm sure VAG are also using the french Beru designed ones too but a later version, they were always trouble in teh past so i hope they have nailed it now

It doesn't do it over such a short reference period. There is a difference between wheel spinning for a couple of seconds or going around a corner for a few more seconds than driving for 10 minutes with a flat!

They don't use wireless sensors, it's purely based on the ABS system and associated things.

[edit] - someone beat me to it!

 

[coggie]

Found the thread I was on about

http://www.seatcupra.net/forums/showthread.php?t=142223

 

[xmichaelx]

Aside from the fact you didn't get a warning, dealers arn't always the best for info.

I could and hope that I'm wrong but it sounds like there 'may' be a fault and the dealer was fobbing you off??? Like I say, I hope that not to be the case.

He had said he'd spoken to the 'head mechanic' as he wasn't 100% on how they worked. He gave what sounded a reasonable technical explaination however, i should have been suspicious when the sensor hadnt gone off when id put the temporary tyre on. The smaller width would surely affect the total distance travelled over 15 miles?

Any thoughts on how i could safely see if there is a problem without taking to the dealer? Ta

 

[Fl@pper]

so more a puncture detection system then a tyre pressure monitor then i guess

 

[Maximus2000uk]

I hit a pot-hole a few weeks ago which totally deflated the tyre - it was empty within about 15 seconds. Oddly, the in-car system didnt pick up the puncture, despite the fact that the car couldnt move over 5mph.

That said, in November, while driving from London to Leeds on a daily basis for 4 days, I picked up three nails in the tyre which created a slow puncture. The in-car system picked up that there was an issue with the tyre, alerted me, and when the tyre was removed I was grateful that I had it!

 

[Leigh15]

I hit a pot-hole a few weeks ago which totally deflated the tyre - it was empty within about 15 seconds. Oddly, the in-car system didnt pick up the puncture, despite the fact that the car couldnt move over 5mph.

That said, in November, while driving from London to Leeds on a daily basis for 4 days, I picked up three nails in the tyre which created a slow puncture. The in-car system picked up that there was an issue with the tyre, alerted me, and when the tyre was removed I was grateful that I had it!

The fact that the car couldn't move would be the reason that the system didn't pick up on the fault - it relies on a certain amount of running on a straight road before it'll realise there's a problem.

The system is intended more for slow puncture situations really

 

[Maximus2000uk]

The fact that the car couldn't move would be the reason that the system didn't pick up on the fault - it relies on a certain amount of running on a straight road before it'll realise there's a problem.

The system is intended more for slow puncture situations really

Fair enough.

 

[/dev/null]

One would imagine that if your car couldn't move above 5mph then you would realise there was a problem without having to see a light on the dashboard...

 

[techie]

what happens when you get wheelspin or go round corners ?

surely they will be usig wireless wheel pressure sensors inside the tyre ? i know a lot of other latest VAG systems do.

Renault have been using em for years and i'm sure VAG are also using the french Beru designed ones too but a later version, they were always trouble in teh past so i hope they have nailed it now

Only Touraeg and Phaeton use sensors and a pick up in the wheel arch.

it know its going around a corner because it can see it via the steering angle sensor which inputs into the ABS system.

Its by no means fool proof but as its just a bit of programming using sensors etc that are all ready there then its a feature they can add at very little cost

And the width of a space saver would have nothing to do with it as the rolling radius is the same.

 

[Fl@pper]

was a toerag sensor that was smashed up recently at work thanks to a friendly local tyre fitter and when i saw the new one it looked similar to Renault ones seen in the past so i wondered how they had all got the technology filtering down so fast

must be quite a fine line of detection to predict an air loss, but as said above isn't it more of a puncture detector ?

i can see a few added little gimmicks being capable with tapping into a system setup with those kind of parameters - interesting

 

[rllmuk]

I recently got two near side side wall punctures due to a pothole and the tyre pressure sensor didn't go off at all.

After having them replaced, the sensor went off about 10 miles later - presumably as I hadn't reset it. I'm impressed.

 

[Pedmondson]

The seat tyre pressure system is poor at best. It tries to identify the parameter of the tyres but it doesn't work with all brands and if you fit wheels larger then standard it never works. The system designed by schrader electronics is far superior. http://www.schraderelectronics.com