These tyre pressure gauge tests are always laughable. There is no âcorrectâ pressure for the MX5; there is an acceptable range, but the required value depends on driver habits, load, environmental conditions, tyre brand and model etc. More important to be consistent. None of these tests use multiple examples of the same gauge to check batch consistency, nor carry out what I would consider to be a rigorous set of repeat readings. Assuming the cheap, Chinese made Halfords gauge is even remotely accurate (if it is, AP Valves, Longacre might as well give up now), the garage gauge is giving a 3.45% variance. Not bad for what is probably a non-calibrated piece of kit. All of the national tyre chains will offer a free tyre pressure check. Main dealers will have their measurement equipment calibrated on a 6 monthly basis, a condition of their franchise. The national tyre places have various contracts with the fleets, and the same requirements will be probably be required of them. Pick a gauge based on known consistency, not on the absolute number. In practice, a battery operated gauge can never be consistency accurate. Then calibrate it against a known certified source (your local Mazda garage for instance). Trading Standards will also carry out free accuracy checks for you.
Sooner trust a calibrated garage gauge than some cheap mass produced tat; they do have a role, but never as an indicator of absolute pressure, more as a tool to warn you about loss of pressure from a tyre.
As itâs displaying 0.0, Iâm going to assume that it displays in half or full PSI. Â So even if it was calibrated to read the correct figure, it would need to round it to the nearest half PSI. Â That makes it +/- 0.25 PSI. Â Thatâs a 1.9% error at 26 PSI and 16% at 32. Â Every gauge Iâve bought or looked at quotes a +/- 1 PSI accuracy anyway.
To me, all that matters is that my tyres are at the same pressure. Â I usually inflate them to 1-2 PSI higher than I want and use the gauge to bleed them down to the indicated pressure that I require.
The pressure gauge says its accurate to within 0.5 psi so if you have tyre that mazda suggest is inflated to 29psi you can be sure the final pressure is going to be between 29.5 and 28.5, better than i was getting at the garage and much more accurate that the plug it tyre inflater I have at home.
It is pretty small and does the job perfectly for me. It doesnât hold the pressure or does any other fancy things and its rather small, but I like its simplicity. Probably it is not perfectly calibrated (and I totally agree with saz9961 about having a correctly calibrated gauges and absolute pressure), but it allows me to set the same pressure in all four tires (and I can do it more accurately than with a âcheapâ digital one). And in the end I donât care if the absolute pressure is 30psi, 31psi, 28psi, etc., as long as I know the indicated pressure that make the car feel good for the given conditions.
I think Sazâs comment is a bit harsh esp as this was a prezzie!
Offhand Iâd say a digital electronic gauge will almost always be better than the local filling stationâs. (which is where most drivers check anyway!) I have a Michelin gauge (similar to the Halfords one) which reads to 0.1psi, stated accuracy IIRC, also about 0.5psi.
On a practical level, a better way of consistently checking pressures and if you do it regularly youâll get good results, esp for tyre wear & general handling (Iâm NOT talking trackday checking here, just everyday normal use!)
So enjoy, use regularly & your tyres will thank you!
I have to be honest and say thereâs no way I can tell a difference in 1psi per tyre on the road; probably not even a few psi. But thatâs probably me, Iâm sure that others can (probably!).
I use the garage one weekly when I top up, but it looks a nice gimmick. However, there is no way that I am going to buy one a few days after Christmas, having had SWMBO saying for weeks âfor goodness sake there must be something you wantââŚMe = âno, nothingâ.
I keep telling myself that tyre pressures are important, but then I look at the many many people I know who never, and I mean NEVER EVER check their tyre pressures.
Trading Standards will also carry out free accuracy checks for you. Â Â I rather think this is no longer true Saz 9961. Â I used to have my gauges calibrated regularly by Trading Standards, not now, certainly where I live.
After scraping the bottom on my Mk2 on speed humps, I check her tyre pressures and instead of 26psi all around, they were only 20psi. A mechanic working on our other car suggested 32psi all around and to my surprise the car goes really well at this figure.
32psi will give lower rolling resistance and possibly greater cornering speed in the dry, but the tyres will wear more in the middle and wet grip will be compromised.
Yes, that was pretty obvious but after a short spell at 32psi I canât stand the harshness so am going to lower them to 28psi. I could feel every piece of grit and every matchstick I drove over when at 32psi.
I donât have much problem in the summer but, during the cold weather when the rubber on the wheels are at their hardest, I find that driving the car for about a mile and then inflating the tyres to 29psi on my mk3 works best. (This is stated in the cars manual â if read criticallyâ)
Of course a good accurate pressure gauge is required. Mine is a Halfords digital gauge which is accurate to 0.5 psi but there are much more accurate ones about which would help.
