Low pressure tyre warning

[Rolfe]

I thought I'd better check my bicycle as I was struggling slightly last time I was out on it. Both tyres were down at 20 psi. Now back at 50 psi, that's better!

 

[hawleybeach]

Your Bicycle obviously doesn't have a TPMS. If it was an MG, the warning would come on at 49psi and not reset even when you pumped the tyres back to 50psi

 

[Rolfe]

To be fair, the MG4 is a lot better than my Golf. That would ping because the temperature changed but I had no way to tell which tyre it was or how soft it was. I had to get them checked every time (sometimes there actually was a slow puncture) and the garage had to reset the sensor otherwise it would never reset.

And the one time I really did have a catastrophic puncture, it didn't trigger.

 

[hawleybeach]

Now that I have a readout to check I rarely need to do the tyre pressures. These Chinese tyres seem to hold pressure very well. At this time of year rising temperatures balances any losses. In autumn I'll need to pump them up once or twice.

I guess most people in the UK won't be having problems with Tyre Pressures at the moment, because the weather is getting warmer. Here in Launceston*, the temperatures have been falling and will continue to fall for the next couple of months

*Launceston Tasmania, not Launceston Cornwall

 

[WonkoTheSaneUK]

To be fair, the MG4 is a lot better than my Golf. That would ping because the temperature changed but I had no way to tell which tyre it was or how soft it was. I had to get them checked every time (sometimes there actually was a slow puncture) and the garage had to reset the sensor otherwise it would never reset.

Before going EV, I had a 2016 VW Up! that did the same.
Luckily for me, the warning light was on the TPMS reset button. I just had to hold that down for 10s after topping up the tyres.

 

[tsedge]

To be fair, the MG4 is a lot better than my Golf. That would ping because the temperature changed but I had no way to tell which tyre it was or how soft it was. I had to get them checked every time (sometimes there actually was a slow puncture) and the garage had to reset the sensor otherwise it would never reset.

And the one time I really did have a catastrophic puncture, it didn't trigger.

Ah yes, the famous VW "something might be wrong with one of your tyres". I am pleased I no longer have that.

 

[Rolfe]

I paid a whole £25 for that as an optional extra!

 

[hawleybeach]

I set 2.8 front and 2.9 rear at 12 degrees Celsius in the afternoon. Given that it is only going to drop to about -4 degrees in the middle of Winter here, shouldn't see any warning alarms for quite a while. Feels happier on the road with a little more pressure, and ride is still not harsh

Moral of the story, put the pressures up as soon as it starts alarming, or preferably before it starts alarming

I've also worked out why the rears alarm first. Given this is a rear wheel drive car, the rear tyres are likely to be running at a higher pressure during normal driving, so alarming at a slightly higher pressure for the rear does make sense

 

[ozzz]

I set 2.8 front and 2.9 rear at 12 degrees Celsius in the afternoon. Given that it is only going to drop to about -4 degrees in the middle of Winter here, shouldn't see any warning alarms for quite a while. Feels happier on the road with a little more pressure, and ride is still not harsh

Moral of the story, put the pressures up as soon as it starts alarming, or preferably before it starts alarming

I've also worked out why the rears alarm first. Given this is a rear wheel drive car, the rear tyres are likely to be running at a higher pressure during normal driving, so alarming at a slightly higher pressure for the rear does make sense

I did the same rear a bit higher and no problem, I had a Skoda that was really bad on tyre warning .

 

[AlexC]

I'm getting occasional TPMS warnings (1-2 per month) which are invalid as all tyres at 2.4-2.6bar.
After anywhere up to 24 hours, these clear and all is well.
Clearly this is likely a software issue, as it should not trigger at 2.4bar, and wonder if there will be a fix.
Anyone else getting this? And the warning going away after a few hours?
It would be nice to also have a settings option or default for UK to show in PSI.

 

[Rolfe]

Merged into the ongoing thread about this. This happens whenever the weather gets a bit colder. Mine started on 20th August! So I pumped them up to 2.7 bar all round, and that fixed it. Lots of discussion above.

 

[fnegroni]

I'm getting occasional TPMS warnings (1-2 per month) which are invalid as all tyres at 2.4-2.6bar.
After anywhere up to 24 hours, these clear and all is well.
Clearly this is likely a software issue, as it should not trigger at 2.4bar, and wonder if there will be a fix.
Anyone else getting this? And the warning going away after a few hours?
It would be nice to also have a settings option or default for UK to show in PSI.

Why should it not trigger at 2.4 bar? Is that the minimum recommended pressure as per the manual/sticker on the door sill?

Hint: it is not. Minimum pressure is 2.5 bar or 37 psi.

There is a slight allowance and rounding performed which means it won’t always trigger at 2.4 bar, and the lower limits for front and rear tyres are not the same

 

[AlexC]

Why should it not trigger at 2.4 bar? Is that the minimum recommended pressure as per the manual/sticker on the door sill?

Hint: it is not. Minimum pressure is 2.5 bar or 37 psi.

There is a slight allowance and rounding performed which means it won’t always trigger at 2.4 bar, and the lower limits for front and rear tyres are not the same

It has only been the rears that have triggered, so maybe they are just under 2.4, rounded up, or need to be closer to 2.5. But the warning has always cleared sometime afterwards, hence my thinking it's over sensitive. I have not added any air since/during the 3 times this has happened. Will see if the warning clears.

 

[fnegroni]

It has only been the rears that have triggered, so maybe they are just under 2.4, rounded up, or need to be closer to 2.5. But the warning has always cleared sometime afterwards, hence my thinking it's over sensitive. I have not added any air since/during the 3 times this has happened. Will see if the warning clears.

Because the ambient temperature and the heat generated through driving have a big impact on tyre pressure.

Ideally, in fact, tyre pressure should be adjusted when the tyres are warmed up and at operating temperature , not ‘cold’.

But for convenience and safety we set the pressure when cold.

 

[AlexC]

Indeed, so outside temp could be factored into the tolerance and adjust accordingly, e.g: not triggering semi-false warnings when cold.

 

[fnegroni]

Indeed, so outside temp could be factored into the tolerance and adjust accordingly, e.g: not triggering semi-false warnings when cold.

I’m not sure what you mean by false warning.

If the temperature is lower and the pressure is lower, you should inflate the tyre.

I don’t think you understand what the recommended pressure is.

When tyres are cold, they need a minimum pressure so that they don’t roll off the rim and the tyre contact patch gives safe driving in all conditions: rain or shine, town, motorway and anything in between.

That minimum pressure has to be met for safety reasons as it is impossible (right now) for the car to predict how fast you are going to drive and what kind of surfaces and if the temperature will rise or fall further.

It is indeed a ‘warning’. It isn’t a fault, it won’t stop you driving. If you know that the tyres will not be abused when cold, and they will warm up enough to get to 2.5 bar or above once at temperature, great. The warning will disappear.
It will come back when the pressure once again falls below the minimum.

For the record, in GT racing it is perfectly normal to drive a couple laps with the pressure warning on all tyres.

Dare I say many cars drive around with overinflated tyres, but I don’t think there’s a warning for that. Anything above 3 bar though I would be wary of.

 

[AlexC]

Fair points. The reason I thought this was a false reading was that I got two warnings also on 2.5 bar about 6 weeks ago on the rears. It’s now consistently warning on 2.4, resetting for a while, then warning. So I’ll accept its now on the edge for recommended pressure and I should add 2-3 psi.

 

[fnegroni]

Fair points. The reason I thought this was a false reading was that I got two warnings also on 2.5 bar about 6 weeks ago on the rears. It’s now consistently warning on 2.4, resetting for a while, then warning. So I’ll accept its now on the edge for recommended pressure and I should add 2-3 psi.

Ok theres something you need to know about how the TPMS works. It’s described in the maintenance manual I think, I need to dig that out though.
I’ll come back to you once I had the correct reference, but goes something like this: theTPMS doesn’t just monitor the tyres when they are rotating but also when stationary. And there are thresholds triggered not by absolute values but by the rapidity by which those values change. That’s so they can detect punctures before the pressure drops below safe levels.
In which case puncture warnings are not going to trigger at the same time as low pressure warnings.
A repentine change in temperature could potentially cause a false alarm in the system.
I’ll double check again as it was a while ago when I looked but that’s the general idea.

 

[blue232]

I am having the same issues, which only started after the car was in for service in May. I get rear warnings daily, every drive and they are at 2.4-2.5bar when I get the warnings. The fronts are the same pressure and no warnings.

If I still get the warnings when I get the car back from the garage I’ll stick them all at 2.6bar and see how I go.

Was interesting to me that I get a warning when the pressure is correct but only on the rears. I got the odd warning before service when it was cold, but since May I’d say there been maybe 4-5 days I haven’t had the warning. And it’s a daily drive to work car, not just a weekender.

 

[fnegroni]

I am having the same issues, which only started after the car was in for service in May. I get rear warnings daily, every drive and they are at 2.4-2.5bar when I get the warnings. The fronts are the same pressure and no warnings.

If I still get the warnings when I get the car back from the garage I’ll stick them all at 2.6bar and see how I go.

Was interesting to me that I get a warning when the pressure is correct but only on the rears. I got the odd warning before service when it was cold, but since May I’d say there been maybe 4-5 days I haven’t had the warning. And it’s a daily drive to work car, not just a weekender.

I think this also might relate to the monitoring while stationary.
After you took that screenshot, did the warning disappear?