Tyre pressure sensors

[RandomGrinch]

Got a reference for that?

Not the most technical info, but one of the first links that appeared (see 'Indirect TPMS'):

How do Tyre Pressure Sensors (TPMS) work?

www.kwik-fit.com

 

[pcaouolte]

Got a reference for that?

Will this do? https://mag.toyota.co.uk/how-does-tpms-work/

Look at their description of the INDIRECT method.

"... indirect system, which uses the existing wheel speed sensors within the anti-lock braking system to ‘measure’ tyre pressure by detecting differences in the rate of wheel rotation. A tyre with less air pressure will have a smaller circumference and therefore spin at a faster rate than a wheel that has not lost air pressure."

 

[DIYspanner]

I'm not a fan of the gadgets they're putting on cars now. Regarding tyre pressures, just look at the tyre wall for a clue.

Having said that, I have an uncle who claims to have passed his advanced driving test many moons ago yet turned up at my house a few years back with a near flat tyre (5 psi) and asked me to check it with my pressure gauge to see if there was enough air in. Had trouble stopping myself from laughing. In fact not one tyre was above 17 psi (Fiesta TDCI)

Regarding the sensor issue, I've given feedback to the car's owner and awaiting a decision.

 

[Avocet]

I've found a tyre pressure gauge perfectly adequate for the past 59 years of motoring
Is this another gimmick that is obligatory if fitted to the car?

Obligatory to be fitted to new (mass-produced) cars for some years now.

 

[Avocet]

Agree.
Out of all the new gizmos in modern cars, this is the one that gives the most trouble.
I check my tyre pressure every time I get the car washed, so every month.
Very rarely I have to adjust pressure.

I used to do that - or before a long drive, perhaps, but on cars with tyre pressure monitoring, I don't bother so often these days.

 

[Avocet]

Looking at the sidewall is much less reliable on cars with low profile or runflat tyres, though.

 

[Alec_t]

... indirect system, which uses the existing wheel speed sensors within the anti-lock braking system to ‘measure’ tyre pressure by detecting differences in the rate of wheel rotation.

Hopefully all four tyres don't lose pressure equally, since then there'd be no indication!

 

[Avocet]

Hopefully all four tyres don't lose pressure equally, since then there'd be no indication!

That's a frequent criticism of indirect systems (and they're less accurate than direct systems), but in reality, it so rarely happens, that it doesn't seem to be a problem in real life.

 

[RandomGrinch]

I was glad of the (indirect) TPMS warning of this one, just before I got to the motorway!

 

[Mottie]

I was glad of the (indirect) TPMS warning of this one, just before I got to the motorway!

View attachment 290474

Did you buy that tyre secondhand? Only asking as you rarely see carbuncles on the inside edge of a tyre - the secondhand shops alway fit them that way round so that they are not seen. In any case, it’s irreparable.

 

[RandomGrinch]

Only asking as you rarely see carbuncles on the inside edge

That's the pointy end of the nail, trying to make its way through the sidewall!
This was a few years ago now - I can laugh now, but the tyre was almost new.

 

[Mottie]

That's the pointy end of the nail, trying to make its way through the sidewall!
This was a few years ago now - I can laugh now, but the tyre was almost new.

Had exactly the same thing on a two week old 245/45/20 Pirelli on my Evoque a few years ago on the last day of a Peak District holiday at the time. Had to come all the way home with the pram wheel on. I had fitted a new set on just before going on holiday. The one replacement tyre cost me £160 and that was to fit and balance myself!