Why aren't tyre gauges certified and tested?

[Albino]

I normally use my own gauge as like most sane bikers I know that petrol station gauges are usually innacurate. Unfortunately though I was going for a fang in the weekend and had the need to rely on a petrol station gauge. I called off my ride because it didn't feel right and I didn't trust the handling. Not happy.

If i had crashed it would have been my fault. But I know better than people like my mother who puts air in her car tyres blindly accepting that the gauge is accurate even though it might be 10psi out.

As we all know the correct tyre pressure is important for the handling of a motor vehicle.

So why aren't these gauges certified and tested? Any one?

And does anyone know if the SCU checks tyre pressures after serious crashes? And if so, what is the percantage of crashes where incorrect pressure was a factor?



Cheer.

[hellnback]

Yeah the SCU do check tyre pressures after a serious crash. Not sure what the percentages would be of that being the main cause of a crash, but after watching the programme on tv most of them were from driver error.
As for the cert and testing of a pump, fuck knows? Obviously no-one thinks it's important enough to warrant it... or that it's the owners responsibility not the garage?

[slowpoke]

So why aren't these gauges certified and tested? Any one?

Because no-one is prepared to pay for it, least of all 99.9% of patrons.
What would be the point anyway, how many times do you see people just drop the gauge etc on the forecourt concrete?

[bert_is_evil]

How do you test if your own guage is accurate? I got a michellin one from Motorad a while back thinking "hey, it's a tyre brand so it must be ok" but now the indicator needle only goes down as far as 10psi (I carry it under my seat, perhaps that's why?) - don't know whether to just add 10psi onto the reading or bin it and get another one.

[Paul in NZ]

Are you telling me you didn't ride because you thought the servo guage could have been 10% out??????

Jesus christ - no wonder I'm happy with my old piles of shit, if it's within a few pounds it's fine. I'd never ride any place if i had to be that accurate about it....

[dasser]

Albino, Who said all petrol station gauges are not accurate ?
Who said the brand new gauge you buy from some shop are any better ?
The only way to know for sure is to have your gauge calibrated by
a IANZ laboratory. You might get some change out of a hundred maybe.
but you will have a nice calibration report of you gauge.
Petrol stations would pass this cost on and it would no longer be free air.
I think most petrol service station gauges are of the 1 % type gauges.
and I would guess the newer digital gauges better than that. 0.1 %

How many motorcycle owner's use the manufacture specs when pumping up their tyre's or is it just abit of a guess?? 30 psi she's right.

Like hellnback said most crash's from wrong air pressure in tyres would be very small if any.

To find a IANZ lab goto www.ianz.govt.nz
If you get stuck PM me and I'll help find a IANZ lab close to you.

[janno]

Gauges are extremely delicate. If you've ever bought your own diving gear or gas bottle gear you soon learn to treat them like glass.

So the servo ones getting happily dropped and knocked about day in day out - it's a wonder any of them read within cooee at all.

[vifferman]

Even though I've got an accurate gauge at home, I carry a pen-type gauge in my jacket pocket anyway. I don't generally use the servo tyre pumps because I can't fit the stiupid fitting on either tyre without severely bending the valve stem to one side. I have yet to find a service station tyre thingo that fits any bike I've owned.

[Albino]

Are you telling me you didn't ride because you thought the servo guage could have been 10% out??????

Ha - yeah, was recovering from the flu and was going for a fang to clear the cobwebs. Bike didn't feel right so i decided to not push it.

Dasser - good points. I know one of the stations gauges was out because i went 20m down the road and tried another one which gave a 12psi difference. Maybe they were both only 6psi out :shrug:

I just thought that with all this going on about road safety that there might be some emphasis on something other than enforcement and speed reduction. Wait - man, am i that dumb?

[Blackbird]

From personal experience, the Accugage brand are accurate to within 1psi or so - have had my 2 checked on our calibration bench at work. Anything with bourdon tube construction (like a barometer) is likely to be pretty accurate. However, because of the construction, they're also more expensive.

With respect to Paul's commenta about tyre pressures, I didn't care too much when I had lighter bikes (err... my old Triumph or GB 400 for example), but the Blackbird is quite sensitive. 42 psi F/R are the recommended cold pressures, and I can feel the handling change if it's around 38 psi for normal road riding.

[vifferman]

From personal experience, the Accugage brand are accurate to within 1psi or so - have had my 2 checked on our calibration bench at work. Anything with bourdon tube construction (like a barometer) is likely to be pretty accurate. However, because of the construction, they're also more expensive.

Mine was about $32, IIRC.

With respect to Paul's commenta about tyre pressures, I didn't care too much when I had lighter bikes (err... my old Triumph or GB 400 for example), but the Blackbird is quite sensitive. 42 psi F/R are the recommended cold pressures, and I can feel the handling change if it's around 38 psi for normal road riding.

Yeah, I can notice if the front tyre (with its cracked'n'leaky valvestem) drops 1 PSI, as it starts to wander, and the bike flops into corners if it gets to about 35.

[Cajun]

i have a small air compressor at home, and check my pressures at home while tires are still cold

I also use a digital gauge, to double check them (since i know my supercheap air pump gauge is out by about 3-4psi compared to digital)

But you can pick up a small compressor kit for wee over $100 i would think, should look at picking one up and doing it yaself from home

[NordieBoy]

A digital gauge goes with me on the bike.
My Mitre10 tyre filler attachment thingy for my compressor is about 1psi out from my digital.
On the DR there's not a lot of difference in handling from 20psi to 36psi.
36 for road and 20 for dirt.

There is a big difference in tyre wear though.

[slowpoke]

You could start a whole thread on tyre pressures.
Personally I reckon you shouldn't be too anal about it....I mean do people adjust tyre pressures depending on the prevailing weather conditions? A tyre at 38psi is going to react quite differently in 5deg C conditons as opposed to 30deg C, not to mention whether you are trundling through traffic or whoopin' through the twisties.
As per the Robert Taylor suspension thread ambient temperature also has a major effect on suspension performance, yet how many people adjust suspension depending on ambient temperature?
Given that suspension does wear, how many people go through a process of optimising suspension on a regular basis?
Lets be realistic about this, a couple of psi either way is hardly going to be noticeable for general road riding given the variables involved.

[MSTRS:Me]

Lets be realistic about this, a couple of psi either way is hardly going to be noticeable for general road riding given the variables involved.

No it's not. However 10/15psi will. And that may not be not uncommon from servo gauges.
Advice is to carry one you trust at (whatever the reading you settle on) and use that to set your tyres when using servo airpumps. Your own gauge may also be wildly inaccurate, but as long as it gives the same reading at the same pressure each time and you are comfortable with that pressure, so what...