Petrol Station air pumps

[BazMV6]

I always assumed that the forecourt based "professional" level air pumps would be more accurate than my portable Halfords one - and also that they would be re-calibrated at regular intervals.

This doesn't necessarily seem to be the case. I checked my tyres at my local BP garage a week ago, and was surprised that they were all down by 5-6 PSI. Nonetheless I topped them all up according to the meter. But sure enough when I checked them myself yesterday they were all now over by that amount. I went back to a different garage this afternoon - and the pump duly took out about 5-6 PSI per corner...

I've complained to the original garage. But what are your experiences? Would you expect forecourt pumps to be more accurate? To be so far out seems potentially dangerous?

Baz.

[Magic919]

I've never expected them to be accurate and check with my own gauge.

[na]

Baz are you joking(?)

they've always been inaccurate and rarely calibrated after initial installation (and I was told this in the late '70s)

using two different forecourt gauges on warm tyres (from use) will give all sorts of discrepancies as there are a lot of permutations of possible errors in doing this

if you stick to one gauge then the inaccuracies should at least be about even over your four tyres (and don’t forget the spare if you carry one)

best is to buy yourself a good manual foot pump and in addition a reliable accurate tyre pressure gauge (or Xmas is coming up) – the gauge on the foot pumps wont be that accurate either

check your tyres when not warm from use and remember the ambient air temperature and pressure will have an effect, say you check on a very hot day but the next day is very cold

did you see your photos of your car on SBDR?

[BazMV6]

It's funny how long-held beliefs can be shot down so quickly..! I'll stick to my own gauge in future.

Yes thanks Nigel - I saw the photos.

[na]

I used had two exactly same made pencil type gauges one always read 2 psi above the other