I hate waiting and queuing to use the air machine at the garage and sometimes you even have to queue again to get a token.
Well, I have one of those tyre inflators/compressors that plugs into your cigarette lighter and reads your tyre pressure, it’s called “Airman” from Aldi £8. I also have just a plain simple digital pressure reader from Home Bargains, but it’s an ex-Woolworths brand.
The problem is that there seems to be quite a difference in readings between the three different methods! I don’t take tyre pressures when the tyres are hot. In fact the tyre pressure seemingly went up from taking a reading at home where it seemed I needed some air, then driving to the garage, where to my susprise I hardly needed any air, and two were just slightly over.
For example: My Airman can show 30psi on the dial, the cheap digital reader can show 24psi and the garage machine can show about 26psi. My tyres should be 26psi.
We keep getting told how important tyre pressure is but what do we believe? I am thinking about getting a new digital compressor
I guess you know that when warm, tyres will be at a higher pressure than when they are cold due to expansion of the warm air in the tyre. I imagine that guages have to be calibrated against a standard. There will be some margin of error allowed for but a difference of 6 psi sound quite high.
Ask at your local tyre shop. They should have a good reference gauge to check your tyres with. You would then know what offset to set your home gauge to, assuming the error is linear…
I use a Michelin digital pump that I plug into my cigarrette lighter socket. I have checked it against a seperate digital guage that I have and both read the same. I also set my tyres to 26psi all round.
I’d be wary of trusting your local free air dispenser, (say at the supermarket). They are likely to get heavy treatment and may not be reliable.
I bought one of those Michelin pumps when I was last at Halfords a few weeks back - it was on offer. When I got home (and after I’d then ripped it open and destroyed the packaging) I remembered there’s one in the puncture repair kit supplied with the Mk3 in lieu of a spare tyre! Doh.
From what I can tell (ie checking the pressures at a good quality digital pump at a garage and then checking on the Michelin) the Michelin is pretty accurate.
I’ve been in the market for a guage for a while, and most quote an accuracy of 1PSI.
Pressures can fluctuate by as much as 10PSI over a journey, so its important to be consistent with tyre temps when checking, thats why I find garage pumps a bit pointless really as the tyres will be warm and hence you would probably underinflate them…
Remember just because it is digital it does not make the gauge any more accurate, it just means it is easier to read. I saw this all the times when I was a calibration technican.
I have a mini digital guage, and then one on the air pump I can plug into the cigarette lighter. Comparing the two readings can give a useful clue to which is the most accurate. I also have a couple of bike pumps with guages for some further comparison.
I do find the mini-digital gauages quite accurate though - pity the batteries don’t last though …
Nope-when temp goes up, tyre pressure does the same, which is why for consistency you should check the tyre pressures when cold (its the “cold” pressure that you see in the handbook).
In the winter you’ll probably find yourself putting a couple more pounds in (cos Winter “cold” is colder than Summer “cold” if you see what I mean). Then when the weather warms up you’ll find yourself bleeding off some air!
All jolly good fun really!
In terms of gauges, it used to be that the pencil-type gauges where said to be the most accurate, but these days I use a little Digital gauge from Halfords. This reads the same as the gauge on my Michelin foot pump and also the Mazda electric pump. If you do high mileages and use the same gauge consistently, you can find out if they are accurate by looking at the tyre wear to see if they are too soft/too hard. I had a gauge for years that I “calibrated” in this way as over-reading by a couple of pounds. Sadly I’ve lost it.
I do have a moblie jump starter,with a tyre pump and gauge etc,which works great,but i dont trust the gauge on it, plus it is only used as a pump in emergencies, i also have used the compressor if feeling really lazy,but i use the gauge like the one from the bay of e to check, but to be truthful … man up ben and get a foot pump,like i do.
Checked against a couple of other gauges (one pen-type and one digital) and all agree within 1-2 psi, but more importantly it makes you look like you know what you’re doing when you use it.
Check your tyres regularly and you should never need to put in more than a couple of pounds, and it’s good for the thighs. I’ll confess to using a 12V compressor though; overinflate a little and then adjust with a reliable gauge.
I’ve had several and they have all suffered the same fate. Now I use a “track pump” technically for bikes but aside from a pants guage, its super quick and easy to use, powerful too. Was only about a tenner from Halfords. I have a keyring type digital guage and it reads to 0.5PSI and seems accurate enough.
I prefer a quality analogue guage, but I’ve lost 2 in 12 months so sticking to cheapies now.
Only ever check tyre pressures when the tyres are at abient temperature, before the car is driven.
I have a Halfords digital tyre guage which has a protective case, gives a nice orange back-lit display (handy at night) it displays the pressure in PSI to 0.5psi and I have had it for nearly 10 years and it still works on the original batteries even though we run 3 cars and the pressures are all checked weekly.
It has also been used in motorsport for the whole duration of its life and whenever I am at a race meeting I usually calibrate it by comparison to the Michelin or Dunlop, Khumo etc. tyre fitters guages and it has always maintained its accuracy to within 0.5 psi whenever checked.
It cost around £16 in 2002, goes to show you get what you pay for…
Nah, think of it like this. Warm air has more “energy” so the molecules are wizzing around that much faster trying to get out. Only the tyre wont let them out, (unless there is a leak of course) so the pressure that the molecules exert on the tyre wall goes up. Same as in a steam boiler. Heat the water/steam and the pressure in the boiler goes up until you let the steam out.
Michelin digital pump works a treat. I paid about £20 for it 2-3 years ago
Indeed. The friction between the rubber and the road creates heat which warms up the tyres thus increasing the pressure.
All the cigarette lighter type pumps I’ve used before take forever to get going, is the Michellin any different? Always found it quicker with a footpump myself. Would snap up a decent electric pump if its any good though at £20 ish.
) so the pressure that the molecules exert on the tyre wall goes up. Same as in a steam boiler. Heat the water/steam and the pressure in the boiler goes up until you let the steam out.