Tyre Low pressure warning

[Boynesider]

Does anybody know the actual pressure change needed to trigger the low pressure warning?

 

I set all my tyres at the recommended pressure for the load I usually carry. Recently I got a warning that one tyre had lost some air pressure. However, there is no indication as to which tyre was affected. A visual inspection did not show any difference so I drove to the nearest garage to check but within the limitations of the gauge at the garage there was no discernible difference. I checked the pressures back home with cold tyres and reset the system. I am still no wiser as to why this happened.

[russ1610]

I have no idea how long you have had your car but mine showed low pressure 3 times in the first two days like you I checked and then re set. I have now had the car for a further 2 months and 2500 miles no further notifications, There may be a settling in process??

[RickTT]

I have no idea how long you have had your car but mine showed low pressure 3 times in the first two days like you I checked and then re set. I have now had the car for a further 2 months and 2500 miles no further notifications, There may be a settling in process??

 

Same here - first 100 miles was a nightmare. then after maybe the 4th reset it was fine.

[Boynesider]

I have no idea how long you have had your car but mine showed low pressure 3 times in the first two days like you I checked and then re set. I have now had the car for a further 2 months and 2500 miles no further notifications, There may be a settling in process??

 

That's strange. I have 17,800 Kms on the clock and this week is the first time this problem has arisen. I still don't know what amount of pressure loss triggers the warning.

[maherto]

I don't think it's based on pressure, it uses the abs sensor to calculate the rolling circumference so if a tyre was under inflated it would rotate more over a set distance. May be check if one tyre is worn compared to the others. If you have Columbus I think it tell you which tyre with a red picture

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[Rascoe]

This happened to me the day I first drove the car. It was down to a stone getting stuck in the tyre tread and causing the pressure sensor to malfunction. Skoda garage confirmed that that was the cause.

[philsmith]

It was down to a stone getting stuck in the tyre tread and causing the pressure sensor to malfunction

 

 

As has been said they do not have pressure sensors but work on rolling circumference, you set your pressures and then set the system, it then measures how many times the wheels turn on a measured distance. This is then stored in the system, if the amount of turns varies, i.e if you have a puncture the overall circumference will reduce and the wheel will do more turns in a measured distance, a warning will be triggered.

I had to reset mine many times in the first 1000 miles but it seems fine now even after a change back to summer tyres.

 

It may be of interest that a neighbour has the same problems of false alerts on his wifes Audi A1

 

It may be that new tyres change in circumference a bit as they run in?

Edited 9 July, 2016 by philsmith

[BillyJim]

This happened to me the day I first drove the car. It was down to a stone getting stuck in the tyre tread and causing the pressure sensor to malfunction. Skoda garage confirmed that that was the cause.

As per the above, it's rotational diameter and not pressure sensing, so a stone in the tread will not cause it to activate.

I've never had the tyre sensors activate but I have one had a warning that there is an error with the sensors. It took two resets to clear it and it's never recurred since (I've switched between summer tyres to winter tyres and back again in that period).

[Rascoe]

As per the above, it's rotational diameter and not pressure sensing, so a stone in the tread will not cause it to activate.

I've never had the tyre sensors activate but I have one had a warning that there is an error with the sensors. It took two resets to clear it and it's never recurred since (I've switched between summer tyres to winter tyres and back again in that period).

Fair enough. I drove off from the dealership with my new skoda, drove around some narrow lanes full of stones, the low pressure warning went off. I phoned the dealership, said they knew what the problem would be and told me to come back. I drove back, they took it into the garage, they came out five minutes later with the car and said that as they had expected, a stone was stuck in the tread, which caused the sensor to activate. They removed the stone and reset the sensor.

[Boynesider]

Thank you everybody for your feedback

[IndrekN]

Hello everybody!

 

The problem with "tire pressure sensor" in our cars is that , its actually not a tire pressure sensor . 
I, as all of you had the same error. Got scared (in highway, 60km to the nearest gasstation) and eventually there was no drop in the tire pressure.

The thing with the so-called "tire pressure sensor" is that calculates how your wheels move. It analyses every data available (except the tire pressure itself).
Meaning , if you get the error light it doesent necessarily mean, that your tire is flat. It might mean that there is something wrong with the ABS or the brakes aswell.

So , when this happens to you, just stop the car check your tires visually, if they look good then drive to the nearest gas-station , check the pressure and restart the sensor.

Thus far (6000km) I have had 2 error lights. None of them proving to be right.

[dstev2000]

Mine's done this once over 10,000 miles, last week in fact. Nothing abnormal when I pulled over and had a look at the tyres. 

 

I wonder if the difference in tyre wear across the front and rear axles will trigger it over time? My rear tyres have much more meat than the fronts - as they would do. 

 

It might be a good idea to reset the system after a routine check of your tyre pressures.

[FelisBengalensis]

This thread is a jinx!! Not had any issues with mine until the day after I read this thread - then the next morning 'Bong' Left rear tyre warning. Stop. Check. Nothing wrong with it!

[IndrekN]

dstev2000, I am quite sure that tire wear will trigger it eventually. But I am not so sure, that any of the cars that we drive (all relatively new) have gone so much mileage for that to become a fact.

My routine after these errors is very simple. I pretty much visit gas station every week. So I always check the tire pressure and reset the system and set it. At the moment 4 months and counting , nothing wrong.

And FYI , winter tire change triggered it aswell. 

Skoda should just explain how the system works, I imagine they get a lot of calls , because ppl are scared that something really happened.

But a bad example aswell. The same system and a brand-new VW. 6 errors in the first week. Nothing wrong. Seventh error at the start of the next week, owner does not trust the system anymore, does not check. Two of the four tires , actually belowe bar and two tires broken.

So, whenever the error light comes up, check the car. Two minutes costs less than two brand new tires .

[Rainmaker]

Don't talk to me about the bloody TPMS... A couple of days after handover, I'm driving at 40mph on a local dual carriageway... *bong*. Mildly alarmed, I manage to leave the carriageway (from lane 3) and get onto the back roads. I get out, inspect the tyres and see nothing amiss. Decide to crawl to the nearest garage, and all the pressures are perfect. Reset the system. The day after, *bong*. Slightly irritated, but now carrying a pressure gauge - all pressures fine. Reset the system again.

 

That weekend, I'm picking up my step-son and inlaws from the airport at 2.30am. We're deep into the motorway network, unlit, and making good progress as the road is for all intents and purposes empty. *bong*  "Stupid bloody system", says I. Just to be safe (because of the speed and location), I ease off the gas and relax my grip on the wheel. No noises, and no adverse effects on the steering. Back on the gas and weaving slightly in the lane. Steering responds perfectly, nothing untoward. Stupid bloody TPMS... Until I got home and spotted the ruddy great big nail hanging out of the shoulder of the indicated tyre. Oops. 

 

So in summary: The TPMS is a pain in the backside at times and does like to cry wolf, but don't get used to ignoring it!

[Kev Hamilton]

I had a warning when towing the caravan a few weeks back.  Checked the pressure (I carry a gauge when towing) and it was at roughly the right pressure but I could not tell if it had lost pressure since I couldn't remember what I'd set it at.  Also, pressures increase with heat and when towing, the rear tyres heat up a fair bit.

When we got to the caravan site, my wee boy noticed a big screw in the tyre so the system did actually work.

[Breezy_Pete]

As per the above, it's rotational diameter and not pressure sensing, so a stone in the tread will not cause it to activate.

I've never had the tyre sensors activate but I have one had a warning that there is an error with the sensors. It took two resets to clear it and it's never recurred since (I've switched between summer tyres to winter tyres and back again in that period).

 

I don't follow your reasoning there, unless you meant will rather than will not?  A (large enough) stone in the tread will change the diameter, won't it, at least once per revolution.

[IanJD]

It's not just Skoda, all the so-called TPMS like this that use ABS sensors suffer from the "boy that cried wolf" syndrome. The BMW 520 I used to have went off every few weeks and it got to the point where I just ignored it. Until I was driving back from Wales with the car stuffed to the roof and it went off, and for once I decided to check just before I joined the motorway. Nearside rear was flat and practically steaming...

 

Unpacked everything, got out the spacesaver from under the boot floor, swapped it for the flat. Now I've got a massive filthy wheel which won't go back into the hole...

 

After a lot of swearing I managed to get enough gear in the spaces under the boot floor and behind the side panels to get the spare in, but I wasn't a happy bunny.

[Montegue]

 

Unpacked everything, got out the spacesaver from under the boot floor, swapped it for the flat. Now I've got a massive filthy wheel which won't go back into the hole...

 

After a lot of swearing I managed to get enough gear in the spaces under the boot floor and behind the side panels to get the spare in, but I wasn't a happy bunny.

You will not have this problem with the Superb as the boot recess easily takes a full size 18" wheel and tyre. Another good reason for not buying BMW!

[BillyJim]

I don't follow your reasoning there, unless you meant will rather than will not?  A (large enough) stone in the tread will change the diameter, won't it, at least once per revolution.

It all comes down to how the sensors actually work. Rotational diameter is a bit of a misnomer used to simplify how it works. It doesn't physically measure the size of the tyres but monitors mainly slippage and rolling resistance which will both change when the diameter changes - and that change in diameter is determined by how much of the tyre is "flattened" when in contact with the road.

Rolling resistance is self-explanatory, it's the friction between tyre rubber and asphalt.

Slippage is the variation in angle between the direction of travel of the wheel and the direction of travel of that part of the tyre that is in contact with the road. Slippage occurs naturally when the tyre is forced to travel in any direction other than straight ahead.

 

A loss of inflation results in more rubber coming into contact with the road surface, thus increasing rolling resistance.

Likewise it makes the tyre less rigid, allowing for a greater slippage angle.

 

So as far as the TPMS is concerned... persistent increase in rolling resistance + persistent increase in slippage = deflating tyre!

 

Rolling resistance and slippage decrease as the air in the tyre heats and expands, increasing tyre pressure. That's why you should ideally only check tyre pressures and/or reset the TPMS with cold tyres.

 

A stone picked up in the tread is either going to be thrown out or ground down very quickly (that clack-clack-clack you hear when you pick one up) before it effects slippage or rolling resistance.

In five years of having this type of TPMS (and seven years before that with TPMS valve sensors) I've had my fair share of stones jammed into my tyres and, whilst annoying and often a bugger to get out, they've never caused a TPMS activation.

The one time it did activate (on my S2) it was a slow puncture caused by a nail so small it could only be found when the tyre was removed from the wheel.

 

I'm not an auto-engineer, but had to learn this stuff as a collision investigator.

[Breezy_Pete]

All the ABS sensor knows about is the speed its wheel is rotating though, which is going to be affected by a local increase in radius caused by a protruberance.

[IanJD]

All the ABS sensor knows about is the speed its wheel is rotating though, which is going to be affected by a local increase in radius caused by a protruberance.

Not unless it's the size of an egg. Think about it, with a small stone in the tread maybe 5mm across, the other 240mm (or whatever) isn't affected, so neither is the slip and effective rolling radius. When the bit of the tyre with the stone in hits the road, the small bit of tyre around the stone is pressed in by a few mm, but the other >90% stays gripping the road as if the stone wasn't there.

 

If the tyres were rigid instead of flexible then you might be right; also your fillings would fall out every time you ran over a pebble...

Edited 8 August, 2016 by IanJD

[IanJD]

 

Unpacked everything, got out the spacesaver from under the boot floor, swapped it for the flat. Now I've got a massive filthy wheel which won't go back into the hole...

 

After a lot of swearing I managed to get enough gear in the spaces under the boot floor and behind the side panels to get the spare in, but I wasn't a happy bunny.

You will not have this problem with the Superb as the boot recess easily takes a full size 18" wheel and tyre. Another good reason for not buying BMW!

And I'm hoping mine comes with one (220TSI L&K estate, spare wheel option, no variable floor) because Skoda are really confused about whether it's full size or a space-saver...

[Breezy_Pete]

Not unless it's the size of an egg. Think about it, with a small stone in the tread maybe 5mm across, the other 240mm (or whatever) isn't affected, so neither is the slip and effective rolling radius. When the bit of the tyre with the stone in hits the road, the small bit of tyre around the stone is pressed in by a few mm, but the other >90% stays gripping the road as if the stone wasn't there.

If the tyres were rigid instead of flexible then you might be right; also your fillings would fall out every time you ran over a pebble...

You might well be right about radius, but it's gonna affect grip/slip, or it wouldn't grind away.

[BillyJim]

Unless TPMS is akin to the princess and the pea (which I know it isn't) a stone capable of being gripped and held by the tread pattern is just not going to make any noticeable difference to tyre performance, for that you'd need an awful lot of stones all jammed in at the same time, an unlikely scenarios.

Even if you took just the ABS rotational sensor as your guide, it would need to exceed the allowance for opposing differential, also extremely unlikely.

You asked for my reasoning and I gave it. I'll just have to agree to disagree that a single stone in the tread is sufficient to trigger the TPMS.