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FzerozeroT
9th July 2004, 07:00
We all 'know' that they're crap and innacurate, here's the proof. The gauge at Caltex on the way out of hami towards raglan reads low by 2psi, i.e. you put too much air in. Resulting in a front wheel side if you have to stop in a hurry :eek5: .

Does anyone know of an accurate gas station in hami, I don't think i can rock around to Quasi's twice a week just to check tyre pressures.

Motu
9th July 2004, 07:08
Go to Repco and buy an Acugauge - be in control of your own tyre presures.

Quasievil
9th July 2004, 07:35
We all 'know' that they're crap and innacurate, here's the proof. The gauge at Caltex on the way out of hami towards raglan reads low by 2psi, i.e. you put too much air in. Resulting in a front wheel side if you have to stop in a hurry :eek5: .

Does anyone know of an accurate gas station in hami, I don't think i can rock around to Quasi's twice a week just to check tyre pressures.

Yeah ya can, and then we go for a ride. I can tell the wife we are off to test our trye pressures :rolleyes:

Firefight
9th July 2004, 08:14
We all 'know' that they're crap and innacurate, here's the proof. The gauge at Caltex on the way out of hami towards raglan reads low by 2psi, i.e. you put too much air in. Resulting in a front wheel side if you have to stop in a hurry :eek5: .

Does anyone know of an accurate gas station in hami, I don't think i can rock around to Quasi's twice a week just to check tyre pressures.



Why don't you do what others do, and buy your own gauge ?


hardly rocket science

F/F

NordieBoy
9th July 2004, 08:53
Push bike track pump and dick smith digital gauge.

Although I think the track pump may be overkill.
I don't really need a pump that will put 200psi in there.

:rolleyes:

Cajun
9th July 2004, 09:40
I always carry my digital tire gage on me, never know when i will need it

When i live at home i also have a nice air compressor there,.

FROSTY
9th July 2004, 09:46
they aint accurate--ohh my god no :bash: :doh:
actually seriously i thought those digital ones were accurate ish
What I used to do was after a ride -like 500 odd yards from home -over inflate my tyres by 10psi
at home before the next ride i'd lower the pressure to what seemed right for the day

Paul in NZ
9th July 2004, 10:53
On the road

On a road bike

Are you SERIOUSLY telling me that a air guage that is 2 psi out will contribute to an accident?

:lol:

What pressure do you use? The one in the handbook??

Kickaha
9th July 2004, 11:11
they aint accurate--ohh my god no :bash: :doh:
actually seriously i thought those digital ones were accurate ish
What I used to do was after a ride -like 500 odd yards from home -over inflate my tyres by 10psi
at home before the next ride i'd lower the pressure to what seemed right for the day


Everyone seems to think that because they are digital that the guages are more accurate,my question is why?

The guage is only as accurate as the guy who calibrated it when it was built and if had a hard night on the piss it might not be any better than one thats been hanging off the service staion wall for the last ten years.

Everyone I know that races or is serious about stuff like pressures uses a quality dial guage and a good one isn't cheap.

FROSTY
9th July 2004, 11:38
my logic is that the digital ones A are newer- ie havent been around for 15 years and B because of the desighn -the gauge is static there is no way they can get abused and smacked around -the bane of any measuring equipment.

Motu
9th July 2004, 12:11
The Acugauge is one of the most acurate,American quality at a bloody cheap price at Repco,many styles to choose from - I have high and low pressure gauges.

Cajun
9th July 2004, 12:17
I know the dial gages(the flasher ones are alot better than digital), but i wouldn't want to be carrying on of those around in an accident might heard more than a little bit of plastic.

also digital take up less room over all, and nice quick and easy, yes they might not be very accutiure, but if you use all the time you know what pressures to use even it reads wrong, i found on my old gsxr1100 a few psi down it would handle a whole lot worse, so was handy when not at home to use the digital to get it to a pressure i knew i like riding it with

Coldkiwi
9th July 2004, 16:34
digital schmidgital... its all about how the spring coils under pressure or how the strain guage moves underthe pressure... both are mechanical items that rely on consistent manufacture of the spring or plate/electronics. I'm sure either version gives reliable answers if its a quality item.

I bought a $45 dial from Mt eden because I knew the gas stations were dodgy but didn't realise just how bad some of them were till I started double checking with my dial. some up to 10psi out!

as for 2psi making a difference, it can sure root a tyre out in a hurry if its being pushed hard on a warm roads and it will definitely make it hotter and possibly encourage it to slide if the tyre is already fairly highyl pressurised.

good point about the manufacturers settings. I think the suzuki sticker typist was smoking some serious herbs when he put 36psi front and rear on my gsxr 'recommended pressures' sticker!

Two Smoker
9th July 2004, 16:42
2 PSI makes a huge difference too my bike, at 30 psi it feels very skiterish and im just waiting for it to lowside :wacko: but 28 PSI feels mint and i can push it as hard as i want and not worry about the tyre......

Paul in NZ
9th July 2004, 17:23
Not the point I was really making...

EVERY bike will work best with certain tyres at a certain pressure which will vary greatly depending upon how hot the day is and how hard you are riding, there is also a HOT pressure and a cold pressure. Measure your tyre pressure tonight and then go for a hard flog, it will go up as the tyres warm.

With high profile tyres like on '70's bikes used to run lower pressures. It allows the tyre to deform more under load increasing the contact patch area when leaned over.

My gut feeling is that 32 front and 35 rear is about right as long for an old munter like my LM2 as the road temperature is not extreme and/or protracted high speed flogging is not being done with a 2 to 4 psi increase in both for load or temperature.

Higher recommended pressures may have more to do with trying to allay owners fears if they talk to mates with more modern machines than the real needs of the older tyres, you can imagine the conversation.

" 'Ere, Boris, wot pressure you run in your back tyre?" Asks Colin of the Mk 2 lemon.

" 'Bout, firty-ate," replies Boris who owns a YZF 750. " Like wot it sez in da book."

" Reckon I'll try that." sez Colin who blows his hoops up to 38 psi cold, rattles off and falls off on the first bend.

I'm quite happy to be told I'm a complete twat who hasn't a clue what he's squalking about but my reasoning seems logical and my experience seems to indicate that this is the way things work.

NOW! There can often be a difference between what the tyre manufacturer recomends to make the tyre last ages and what the bike maker recommends to make his bike seem nice (oh alas alack, what to do)

Well I tried this and it works... (for me but then I'm a fat idiot on a munted old dunga)

Reading Guzziology during a wet day, I happened to read the section on tyres. It didn't all stick in my mind, but there was some advice about setting the tyre pressures by trial and fang and measure.

It went something like this:

Think of a number between 25 and 50. Put that in your tyres cold and go for a (short) fang.

Measure the pressure with the tyres hot.

If it HASE NOT risen by 10% (I think, check the book) then drop the pressure by 10% and go for another fang.

If it has risen by MORE than 10% then increase the pressure by 10% and go for another fang.

Repeat until busted for fanging around the shopping centre carpark or tyre pressure changes by 10%.

It made sense at the time...

What you are aiming for is an increase in hot pressure of 10% from cold. That means your tyre is heating up about right! Unless its a special race tyre sold with a free set of knee sliders to demon racer types.

Paul in NZ

ps. Make ALL the measurement on the same gauge. Who cares what the pressure REALLY is, as long as you always use the same gauge?

PPS. For gods sake. I'm a fat old twat that knows shit all about anything. Don't for gawds sake take this as gospel and go kill yourself. Gentle experimentation is what works.

Paul in NZ
9th July 2004, 17:24
Appologies to the AIGOR site where I nick some of the text from

FzerozeroT
9th July 2004, 18:34
Paul, you sound like you are on the right track, but that will vary across tyres as you also say, and yes, i do have super sticky race tyres, (I should go and find out who has my sliders) so as I have a carcass which is softer when the tyres warm up will the rubber stretch more easily and make the pressure the same?

I could go and buy a pressure gauge but by the same token they need to be calibrated accurately every 12 months if you want true accuracy.Then i would put aforementioned tyre presure gauge, as well as some chain lube, visor cleaner, raincoat, foot pump, tyre levers, patches, spare chain links into my pockets, no, wait, i have leathers without pockets, i'll put them into my belt bag with camera and wallet, nope sorry, i have to wear a backpack, nope, don't like the feel and speed hump won't allow it. you get the idea.

I want to be able to ride to a gas station fill up and check tyre pressures and go. BP tristram street seems ok,

TS - i know what you mean, 32 in the front and the front wheel slides under braking, 28 and it doesn't stand up again out of a lean.

If anyone can find out more of pauls idea i would love to hear it, even if anyone knows of an optimum tyre temperature chart for different tyres?

Racey Rider
9th July 2004, 19:15
TS - i know what you mean, 32 in the front and the front wheel slides under braking, 28 and it doesn't stand up again out of a lean.


Have been told, the top racers (ie. well known names who ride the big bikes.), all had a go at SS 150 racing when it first started. And they reckon the go was 26psi in both front and back hoops.

I have (In the limited track days I've had), been trying a range of pressures. Have been as low as 24psi in the front, to try and get the tyre to heat up to a sticky level. Maybe I'm not pushing it as hard as some in the corners, but I never noticed the 150 not ready to stand up.

Dave ( :not: ) once said the tyre should increase by 6psi from cold to hot. If it doesn't, ether ride harder, or lower the pressure.

FROSTY
9th July 2004, 19:17
I think tyre pressure is one of the great black arts of motorcycling.
a different tyre on the same bike same rider seems to need different pressure.
same tyre same bike different rider-again different pressure.
For bucket racing we ran rediculously low pressures in winter to get the tyres to work--like 20psi
It sounds like Paul is onto something here with his 10% idea except maybee it would vary according to the load on the bike etc.

Two Smoker
9th July 2004, 19:21
Have been told, the top racers (ie. well known names who ride the big bikes.), all had a go at SS 150 racing when it first started. And they reckon the go was 26psi in both front and back hoops.

I have (In the limited track days I've had), been trying a range of pressures. Have been as low as 24psi in the front, to try and get the tyre to heat up to a sticky level. Maybe I'm not pushing it as hard as some in the corners, but I never noticed the 150 not ready to stand up.
Yep good old Nicko still has his beast of an RG150 lol, i have played a bit and i like 28 psi, any lower and my tyre wear would be insane :wacko: dont mind having 30psi in the rear though.....

Paul in NZ
9th July 2004, 19:40
I think it would also vary according to the size of the tyre.

A big tyre would have a LOT of surface area to shed heat? Dunno??

I know what works on the Guzzi and what to add when Vicki piles on the back with a little day pack (it would outfit the Foreign Legion for 6 months in the Artic)

The point is, not just blindly adding air but trying to achieve a result based on the important item. Getting your tyre to the correct temperature so it works without getting it too hot and wrecking it.

Remember an early post from me where I went for a ride with 3 fat tyred members of this list and they were slithering about on lichen covered roads when the skinny tyred LM2 tracked true and straight?

I dunno... We will all be checking our tyres every 5 minutes now!

Paul N

Sun well over the yardarm lads... :rolleyes:

Paul in NZ
9th July 2004, 19:42
Paul, you sound like you are on the right track, but that will vary across tyres as you also say, and yes, i do have super sticky race tyres, (I should go and find out who has my sliders) so as I have a carcass which is softer when the tyres warm up will the rubber stretch more easily and make the pressure the same?

If anyone can find out more of pauls idea i would love to hear it, even if anyone knows of an optimum tyre temperature chart for different tyres?

Check the manufacturers web sites. They are usually really VERY good and I would have no problem asking them.

Cheers

Kickaha
9th July 2004, 20:13
Remember an early post from me where I went for a ride with 3 fat tyred members of this list and they were slithering about on lichen covered roads when the skinny tyred LM2 tracked true and straight?



Same reason a narrow tyre can be better in the rain or on a shingle road,more ground pressure per cm,cuts through rather than skating about on top..

Motu
9th July 2004, 21:38
I always run low pressures,everyone freaks out at my 25psi rear 20psi front,but it suits my bikes,like that's 34 yrs of bikes,and my tyres.Like Paul says,it allows the older cross sections to deform on the road surface and for a knob the side knobs actualy fold over.Anything over 28 and it feels like I'm riding on oil.On the dirt track pressure directly affects traction - low pressures give traction....want less hook up out of the turn,increase the pressure.I'm gunna talk to the OWL tomorrow - he can write a book on the difference 1/2 psi makes on a dirt track.

Posh Tourer :P
10th July 2004, 11:09
I think tyre pressure is one of the great black arts of motorcycling.
a different tyre on the same bike same rider seems to need different pressure.
same tyre same bike different rider-again different pressure.
For bucket racing we ran rediculously low pressures in winter to get the tyres to work--like 20psi
It sounds like Paul is onto something here with his 10% idea except maybee it would vary according to the load on the bike etc.

I think you've hit a reason why pressures vary and there is no one perfect pressure even for each tyre. Rider weight could be very important, and thus you just have to experiment and find out what works for you.

As for garages, f00t, settle on a garage, borrow a gauge and find out how out it is and use that one all the time. Alternatively, you could just add a gauge to your toolkit under the seat... or make it the beginning of a toolkit...

What?
10th July 2004, 19:27
I could go and buy a pressure gauge but by the same token they need to be calibrated accurately every 12 months if you want true accuracy.

I want to be able to ride to a gas station fill up and check tyre pressures and go. BP tristram street seems ok,
Recalibration every year seems a bit OTT. A good quality guage, in normal use, should hold it's calibration for much longer.
If you ride before checking your tyre pressure, you may as well have an inaccurate gauge. How you ride, road and weather conditions will all influence your pressures when you get to the servo. For my two pennies, buy a good gauge (accugauge at ~$45 is good and generally very accurate out of the box) and go to the Whorehouse & pick up one of those $20 12volt compressors. They aren't particularly fast, but do work. My first one survived something like 15 years of frequent use, so $20 isn't a bad investment...

RiderInBlack
10th July 2004, 20:01
I haven't trusted petrol station pressure gauges ever since putting in what the garage gauge said was 42PSI and checking it with mine and finding it said 50PSI:eek5: :2guns:

Your better carrying your own gauge. Then even if it is not accurate at least it is consistant (like it will be the same when you are in Whangarei as when you are in Bluff:stupid: ).

wkid_one
10th July 2004, 21:05
I have said this before - ideally you want to know you optimum HOT TYRE pressure.

Measuring your cold pressure is great - however so many variables affect what the working tyre temp will be when they get up to heat - road surface, road temp, ambient temp, riding type, riding style.

You could ride on 3 diff days - each with the same cold tyre pressure and end up with 3 completely different HOT tyre temps.

Pro-Teams have absolutely no interest in what their cold pressures are - only in what their hot/working pressures are - as at the end of the day, cold pressures mean fuck all as a tyre is never cold when it is working.

Next time you go for a ride and the bike feels good - take a pressure reading - then you will know what is the best working temp for the tyres.

Do you change your tyre pressures winter to summer? Why not - I can guarantee without changing - you are riding with significantly less pressure working working in your tyres in winter - no argument - yet you may have the same cold pressures.

Re the gauge calibration - just take it in to a bike shop and compare to their units which are usually calibrated - you will then know how much you will need to adjust your reading on your gauge when filling up.

Kickaha
10th July 2004, 21:32
I have said this before - ideally you want to know you optimum HOT TYRE pressure.




Well if you want to be really picky I would say ideally you want to know your optimum HOT TYRE temperature,don't bother with a pressure guage rush out and spend several hundred dollars on a pyro :bleh:

FzerozeroT
12th July 2004, 18:06
i got a gauge today, stuffed if i was running 26/30 and after wearing out half my sliders and pressures were 27/30!? tyres were still coldish, so i must be slow :P and it was feeling wallowy, i'll stick with 30/32, may not be 'optimum' temp but it's predictable and feels good and thats what counts

AMPS
13th July 2004, 09:56
Accu-Gages are around $36 for the basic unit or $69 for the model with pressure lock and short hose.
Lou

RiderInBlack
13th July 2004, 17:24
THinks yet again for you advise WKid_One. Am test the Heavy Hamster's hot Tyre pressures. Felt good at 36psi & 42psi Hot after 40Km open back road (cold was 32 & 38psi but it was a cold day:niceone: ) on my gauge (Whangarei Petrol station with digital was with in 1psi of my gauge).