All season tyres ??

[kurienp]

Same here

from a safety standpoint, the active TPMS picks up even small loss in pressure. A few months ago, started the journey with 44 PSI from a hot south England, to a much cooler north pennines. Parked overnight in a layby and the tyres cooled and pressures in all 4 dropped to about 38. as soon as I started rolling in the morning got an immediate warning for all 4 that the pressure was low. If it was the standard system, it would have considered all 4 wheels rolling at the same speed and not thrown up an error and I may have continued on my journey with low pressure and possibly damaged a tyre or two in the process.

 

[Hawthorn37]

from a safety standpoint, the active TPMS picks up even small loss in pressure. A few months ago, started the journey with 44 PSI from a hot south England, to a much cooler north pennines. Parked overnight in a layby and the tyres cooled and pressures in all 4 dropped to about 38. as soon as I started rolling in the morning got an immediate warning for all 4 that the pressure was low. If it was the standard system, it would have considered all 4 wheels rolling at the same speed and not thrown up an error and I may have continued on my journey with low pressure and possibly damaged a tyre or two in the process.

I’ve got TPMS on my Volvo, and the differential can still be quite high before getting a warning in my experience. Also had it on an X3 and an A6. The result was that replacement tyre costs were ‘inflated’ (poor pun), so I’m happy to have only a basic system for real emergencies. I tend to check the tyre pressures before every long trip rather than trusting automation, and eyeball the tyres for defects and wear.

 

[B J G]

from a safety standpoint, the active TPMS picks up even small loss in pressure. A few months ago, started the journey with 44 PSI from a hot south England, to a much cooler north pennines. Parked overnight in a layby and the tyres cooled and pressures in all 4 dropped to about 38. as soon as I started rolling in the morning got an immediate warning for all 4 that the pressure was low. If it was the standard system, it would have considered all 4 wheels rolling at the same speed and not thrown up an error and I may have continued on my journey with low pressure and possibly damaged a tyre or two in the process.

Tyre pressure goes up by 4 to 6 psi after a few miles and varies with barometric pressure and altitude.
Having a lowish cold pressure on start up wouldn't lead to tyre failure, assuming within a few psi of cold setting figures.

 

[kurienp]

Tyre pressure goes up by 4 to 6 psi after a few miles and varies with barometric pressure and altitude.
Having a lowish cold pressure on start up wouldn't lead to tyre failure, assuming within a few psi of cold setting figures.

True, it would have warmed up, but with the difference in temp, it would not have gone back up to the required pressure.

Low pressures can cause many miseries, tyre failure being one of them, of course depending on many other variables. Had to do a stretch of forest road that day, which could have. Normal roads, less so.

 

[andyinluton]

[

from a safety standpoint, the active TPMS picks up even small loss in pressure. A few months ago, started the journey with 44 PSI from a hot south England, to a much cooler north pennines. Parked overnight in a layby and the tyres cooled and pressures in all 4 dropped to about 38. as soon as I started rolling in the morning got an immediate warning for all 4 that the pressure was low. If it was the standard system, it would have considered all 4 wheels rolling at the same speed and not thrown up an error and I may have continued on my journey with low pressure and possibly damaged a tyre or two in the process.

If thats the case, you hadn't set the pressures correctly. If they had been set at the correct pressure when cold in the South, they would have been at the correct pressure when it was cool in the North. The pressure would have increased as the tyres got hot but will drop back to the original settings as they cool down.

 

[B J G]

True, it would have warmed up, but with the difference in temp, it would not have gone back up to the required pressure.

Low pressures can cause many miseries, tyre failure being one of them, of course depending on many other variables. Had to do a stretch of forest road that day, which could have. Normal roads, less so.

I've got Tyrepal system which gives a constant pressure display. Cold pressure varies day by day and I found that a reading of 38 can be 42 a few days later or vice versa. Running pressure seems to be more relevant.

 

[Velma's Dad]

If thats the case, you hadn't set the pressures correctly. If they had been set at the correct pressure when cold in the South, they would have been at the correct pressure when it was cool in the North. The pressure would have increased as the tyres got hot but will drop back to the original settings as they cool down.

Absolutely. From other threads on this forum there seems to be a lack of understanding that tyres change pressure substantially with temperature (both ambient and due to friction with speed), up to 10psi, and that the recommended cold pressures are aimed at achieving a balance between grip, wear and fuel economy, at typical vehicle load levels but all those things will vary a lot in the real world from day to day.

In any case, "cold" temperatures will obviously be different on a hot summer afternoon and a cold winter morning. But it's not worth worrying about unless you're trying to set lap times.

Modern tyres can cope with a wide range of pressures and temperatures and only a grossly under inflated tyre poses any serious risk, ie of either blowing out or of rolling off the rim while cornering.

Unfortunately a lot of drivers don't seem to be able to detect the change in vehicle handling from a punctured tyre, or to be capable of doing basic cold pressure checks with a gauge or even of just looking at the tyres before they set off in the morning (and admittedly it's harder to see how much modern low-profiles have in them, versus old full profiles), hence the need for all this TPMS stuff.

 

[Wesel]

from a safety standpoint, the active TPMS picks up even small loss in pressure. A few months ago, started the journey with 44 PSI from a hot south England, to a much cooler north pennines. Parked overnight in a layby and the tyres cooled and pressures in all 4 dropped to about 38. as soon as I started rolling in the morning got an immediate warning for all 4 that the pressure was low. If it was the standard system, it would have considered all 4 wheels rolling at the same speed and not thrown up an error and I may have continued on my journey with low pressure and possibly damaged a tyre or two in the process.

There is no reason for all 4 tires to lose air at the same time. Either they weren't inflated enough before, or the TPMS is the problem.

 

[kurienp]

[
If thats the case, you hadn't set the pressures correctly. If they had been set at the correct pressure when cold in the South, they would have been at the correct pressure when it was cool in the North. The pressure would have increased as the tyres got hot but will drop back to the original settings as they cool down.

Disagree with the fact that the tyre pressures were not set correctly. There was a significant difference in what you'd call cold in the south and cool in the north. It was much colder up north and that can cause further pressure drop. Remember, it is the temperature in this case that is making all the difference.

 

[kurienp]

There is no reason for all 4 tires to lose air at the same time. Either they weren't inflated enough before, or the TPMS is the problem.

It is not a case of loosing air. The temperature differential at the two locations was large enough to report lower pressures.

 

[kurienp]

... and before this thread further veers off into - how some people understand tyre pressures better than others and etc etc. ...

1. The passive TPMS works on differential. If one wheel is rotating faster than the others, due to lower circumference, due to lower tyre pressures, the ABS sensor detects this and reports a low pressure
2. The active TPMS, monitors each tyre pressure against a reference value.

In my case, as the pressure in all 4 tyres dropped (due to the temperature differential in the cold temp), the active TPMS picked it up instantly. A passive TPMS would not have, as all tyres were rolling the same at a lower pressure.

The advantage of an active TPMS.

 

[WelshGas]

How did we manage in the old days without TPMS, active or otherwise.

 

[kurienp]

How did we manage in the old days without TPMS, active or otherwise.

WG, that's a different discussion altogether. There are people on here who can take the van apart and put it back together and others who will ask where the black rubber bung fell out from and others who can take the mechanical part and put it back without batting an eyelid, but will ask on the electrical side of things and vice versa. Everyone is different and that is what makes this forum so helpful with all the varied inputs that come in based on people's experience and areas of strength.

 

[Velma's Dad]

In my case, as the pressure in all 4 tyres dropped (due to the temperature differential in the cold temp), the active TPMS picked it up instantly. A passive TPMS would not have, as all tyres were rolling the same at a lower pressure.

The advantage of an active TPMS.

Why is that an advantage? The TPMS just told you (in effect) that the tyres that had been warmer, were now cooler, and that the pressures had thereby changed, utterly predictably. Seems to me to be absolutely useless information, as common sense would have told you the same thing, and no corrective action was needed.

 

[andyinluton]

The only time the TPMS is really useful is when you are trying to get home & have a puncture & no spare. Pump the tyre up & drive carefully & you can see when the pressure has dropped enough that you need to get pumping again.

 

[kurienp]

Why is that an advantage? The TPMS just told you (in effect) that the tyres that had been cooler, were now warmer, and that the pressures had thereby changed, utterly predictably. Seems to me to be absolutely useless information, as common sense would have told you the same thing, and no corrective action was needed.

VD, on information supplied, useful for some, useless for others.

However on the advantage - When waking up early morning in a layby in the middle of nowhere, there are other pressures that come to mind first before tyre pressures. A timely ping from the system has possibly avoided issues further down the line. That's it.

I would not classify it as a lack of common sense, but a ping to help focus on a priority that may have missed being noticed. The active TPMS helped with that and hence the advantage.

 

[Velma's Dad]

How did we manage in the old days without TPMS, active or otherwise.

Actually it reminds me of the old Soviet era military trucks that had cab-controlled tyre inflation/deflation kit so they could adjust the pressures before going onto soft ground. (Although you'd think they would have just pushed a couple of conscripts under the wheels whenever they got stuck.)

I think the US Humvee may still have such a system also.

 

[B J G]

... and before this thread further veers off into - how some people understand tyre pressures better than others and etc etc. ...

1. The passive TPMS works on differential. If one wheel is rotating faster than the others, due to lower circumference, due to lower tyre pressures, the ABS sensor detects this and reports a low pressure
2. The active TPMS, monitors each tyre pressure against a reference value.

In my case, as the pressure in all 4 tyres dropped (due to the temperature differential in the cold temp), the active TPMS picked it up instantly. A passive TPMS would not have, as all tyres were rolling the same at a lower pressure.

The advantage of an active TPMS.

Slight aside

What is the life of a VW TPMS sensor?

I ask as I had the Tyrepal valve outer type which have a replaceable battery. The internal type as per VW had a 3 year battery life which was not replaceable, ie new set of sensors needed.

 

[kurienp]

Slight aside

What is the life of a VW TPMS sensor?

I ask as I had the Tyrepal valve outer type which have a replaceable battery. The internal type as per VW had a 3 year battery life which was not replaceable, ie new set of sensors needed.

The first set that I have on right now, were sold as used on eBay. Mentioned as used for 1 year (mileage not mentioned). I have had it for another year now, so 2 years in all and still working good. Yes, it may be 3 years and you are right, it does not have a replaceable battery. Each sensor is about £35. So yes, on the expensive side versus a button cell that needs to be replaced on a Tyrepal.

Once any one of them wears out, I will try a repair as it may just involve changing the battery within a sealed unit ... and as always, there are videos on YT on how to do it

 

[B J G]

The first set that I have on right now, were sold as used on eBay. Mentioned as used for 1 year (mileage not mentioned). I have had it for another year now, so 2 years in all and still working good. Yes, it may be 3 years and you are right, it does not have a replaceable battery. Each sensor is about £35. So yes, on the expensive side versus a button cell that needs to be replaced on a Tyrepal.

Once any one of them wears out, I will try a repair as it may just involve changing the battery within a sealed unit ... and as always, there are videos on YT on how to do it

Needing tyre removal/refit and balance was another factor adding to cost.

Had a look at the You Tube Kamakazee DIY methods and definitely wouldn't go down that route.

Bit of delving and found life quoted as 5 years approx. for sensors.

No doubt there will a suggestion to have new sensors fitted when tyres are replaced.

 

[Californication69]

Same here

Same thrice