Tyre Warning

[poloag]

Hello,

I got a warning today while driving that rear right tyre was low on pressure, but looking at it, it seems fine.
I did pump up the tyres 2 weeks back, are you meant to reset the setting in the console after checking tyres?

Thanks in advance.

[Mikeso51]

The tyre pressure monitoring system works by comparing the set value for each wheel with the current reading. The system doesn’t actually measure pressures. It works in conjunction with the ABS system, and uses the rotational speeds of the wheels. Putting it at its most basic, If the pressure changes, the wheel diameter changes, so the wheel rotational speed will change compared to the original setting for a given vehicle speed. In practice the software algorithms used are quite involved and, for example, take account of all four wheels to allow for changes due to temperature. I believe that the system is also less sensitive to slow changes than sudden drops, and there is averaging to allow for cornering effects etc. Since the system relies on wheel speed measurements, it obviously only works when the car is moving. When you reset with the car stationary, the system is instructed to take new measurements the next time the car is moving. I believe it averages over a distance of a several miles. These measurements then become the references.

So coming back to your original question, yes, it’s a good idea to reset when you pump all your tyres up to the recommended settings.

I have never seen a definitive statement from the manufacturers regarding the sensitivity of the system, but from my own experience on two VAG cars you need several pounds change in pressure in one wheel to trigger a warning. I’ve also had two occasions when I’ve hit potholes and the system has given a warning message even though there was no loss of pressure. This was presumably because there was a sudden change in wheel speed.

HTH

Mike

[poloag]

Thanks for in depth reply.

I just checked the reading at it was bang on 36psi (cold tyre), what I had put in 2 weeks back.
I reset it in the console and error is gone.

I wonder if the TPM in the tyre is on its way out?, I did read that they need to be replaced every 6yrs or so.
I thought they measured any loss of air too, as they are connected to the valve.

Thanks

[SRGTD]

Thanks for in depth reply.

I just checked the reading at it was bang on 36psi (cold tyre), what I had put in 2 weeks back.
I reset it in the console and error is gone.

I wonder if the TPM in the tyre is on its way out?, I did read that they need to be replaced every 6yrs or so.
I thought they measured any loss of air too, as they are connected to the valve.

Thanks

The Polo’s TPMS is an indirect system, so as @Mikeso51 has said, the car it’s ABS sensors to measure the rotational speed of each wheel and will trigger a low pressure warning if it senses one wheel rotating at a different speed to the others.

It’s cars with a direct TPMS that uses TPMS valves in the wheels; your car doesn’t have these so no need to buy any.

[poloag]

thank you.

[RUM4MO]

In my experience of running 2 VW Group cars with this feature, what I describe as "ghost" warnings will happen now and again, but I always stop as soon as safe to do so, to give the tyres a look and squeeze!

First and so far, only event with my wife's 2015 Polo, happened when we were on a motorway and visiting someone in hospital - every time I tried to find a quiet place to stop someone was on my tail, very annoying.
First and so far, only event with my S4, I was kind of less stressed about having experienced this with my wife's 2015 Polo, so just drove the 400 meters home and checked the tyre pressures as soon as I stopped, again no drop in pressure!
One thing that I've always considered is that if you had a partially seized brake then the hub would get hot and so increase the tyre pressure - remember this system is just looking for a difference in its stored values so an increase is just as important to it as a decrease in pressure - or circumference.

[poloag]

thank you