www.jec.org.uk

Had the F type for a week now. Just getting used to it all. TPMS says tyres are all at 38psi cold. Should be 37. Thing is, 37 is what I set them to, cold, on the local filling stn new digital air line, which I believe is checked regularly by weights and measures for accuracy. Which is likely to be right? Can you rely on what TPMS says? Any comments please? Regards. Ian.

I can't imagine that it can be that accurate. The difference between the 2 is less than 3%which I would have thought a reasonable margin of error.
I thought these TPMS systems were more designed to monitor for an unexpected drop in pressure than absolute values?

Sounds reasonable, Brian, slightly worrying that it's reading higher than the actual. However, I'll assume you are right and leave the pressures as they are. Thanks for the input. Regards, Ian.

Sorry David, no idea why I called you Brian! Ian.

Ian,
You could use a tyre pressure gauge !

I suppose, yes, but then I thought the digital air line would be more accurate than a £2.50 gauge!! I always use it as a rough guide only. To be honest, I'd rather the car did not have the TPMS valves at all. Heard too many tales of problems with rogue readings etc, hence my original post. Always managed fine in the past without them! Think I'll just ignore the TPMS and carry on as I have in the past,checking pressures manually, weekly! Regards. Ian.

Yes, I'm with you

Ian,

Part of the difficulty may be that unless your tyres are filled with nitrogen, even driving a short distance to your local filling station will have caused a slight temperature rise in your tyres and a slight true pressure difference to cold.

I would suggest buying a decent pressure gauge (which are pretty cheap these days) and always checking your tyre pressures from cold at home for the most accurate and consistent readings.

Cheers

Paul