Tyre Pressure Gauges - Accuracy and Recommendations

[RobM77]

It's a dull rainy day here, so out of curiosity I've just gathered together five pressure gauges that we have lying around and measured the same rear tyre of my BMW with each one to compare the results, which are below. Very little air escaped when applying each gauge, and to ensure that this was the case I went back to the 1st one after the 5th one to check the result was still the same, which it was. There's not been any sun all day and I haven't driven the car since Friday evening; besides the tests only took about a minute to complete.

My results:

Gauge	Pressure (psi)	Comment
1	37.0	A tube and gauge type that I used to use on my racing car - it was about £30 IIRC
2	36.5	A cheap electronic one that my wife's had for years
3	33	The gauge on a cheap and cheerful £5.99 Halfords foot pump
4	34	A new mini electronic one I've just bought to carry with me when out cycling
5	35	The in-built gauge on a portable 12V pump

There's quite a difference between them all. From experiments in the past I know that a 4psi difference like that is enough to experience less mpg and poorer handling if I'm setting my pressures incorrectly. Does anyone have any insight into what gauges are the most accurate, or would care to comment on the above?

[vikingaero]

Get one of these along with the cycle inflator:

http://www.bestrestproducts.com/p-44-ez-air-gauge....

Cycle inflator is a misnomer and can be used on cars/trucks.

[BritishRacinGrin]

I don't even bother looking at gauges built in to footpumps or 12v compressors . I use analogue dial gauges- a longacre 0-30 PSI for racing and a 0-60 PSI draper gauge for road cars. The draper was only a tenner but it seems accurate enough, certainly more so than integral gauges etc.

[kambites]

I've generally found that most gauges are fairly accurate when new, but that even a small impact (by that I mean tapping it against your hand, not dropping it out of a first floor window) can knock them out quite significantly.

I've currently got two that read within about half a PSI of each other; if they start to diverge, I'll buy another two and see what matches what.

[PlayersNo6]

I've got a brass, analogue ITC one that I've used for years. Just googled it and the reviews are pretty average now :

http://www.autoexpress.co.uk/accessories-tyres/419...

You can also upgrade it with an extension hose and a protective rubber dial cover.

However, unless you're going to get any consumer level gauge professionally calibrated on a regular basis - how can you really trust any of them?

[Ozzie Osmond]

RobM77 said:

There's quite a difference between them all.

Try this. Park your car overnight where the sun will shine on one side of it in the morning. Then check the tyre pressures at,

• 8.00 a.m.
• 11.00 a.m.
• 2.00 p.m.

Make sure you check both sides of the car and write down the readings.

I don't think you'll be worrying too much more about pressure gauges.

[HertsBiker]

Ozzie Osmond said:

RobM77 said:

There's quite a difference between them all.

Try this. Park your car overnight where the sun will shine on one side of it in the morning. Then check the tyre pressures at,

• 8.00 a.m.
• 11.00 a.m.
• 2.00 p.m.

Make sure you check both sides of the car and write down the readings.

I don't think you'll be worrying too much more about pressure gauges.

I notice this a lot, good post.

[RobM77]

HertsBiker said:

Ozzie Osmond said:

RobM77 said:

There's quite a difference between them all.

Try this. Park your car overnight where the sun will shine on one side of it in the morning. Then check the tyre pressures at,

• 8.00 a.m.
• 11.00 a.m.
• 2.00 p.m.

Make sure you check both sides of the car and write down the readings.

I don't think you'll be worrying too much more about pressure gauges.

I notice this a lot, good post.

That'll make a huge difference, yes. Howeve, once you're moving and presenting different sides of the car to the sun it no longer has an impact. I've tested pressures hundreds of times during testing and you can never tell which side was in the sun when the car was stationary. This is why it's so crucial to set pressures in the shade, you need a baseline at ambient air temperature.

[Fleckers]

Guy across road seems to check his with a kick of a steel toe boot

[BritishRacinGrin]

Fleckers said:

Guy across road seems to check his with a kick of a steel toe boot

You should ask him when it was last calibrated.