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View Full Version : At what PSI do tubed tyres go !!BANG!! ?



Flyingpony
22nd January 2007, 12:17
I asked for 36psi but got given 48psi instead !! :gob:

So at what PSI do tubed tyres go !!BANG!! ?

Inflated the FXR's tyres at BP on Riccarton Road but didn't feel happy about it. It's one of those units where you press a button to set the pressure you want and then push it on the air nipple. The machine will then beep when it's ready. This machine stopped several times with error codes 1 and 2.

I then rode to the next nearest station I knew to verify the pressures. Both tyres should have been inflated to 36psi but in fact they weren't. The front had 33 and the rear a whopping great big 48! :nono:

I rarely visit that BP station but since I was in the area ... I'll never go back there again.

I like stations which have the good old fashion self pressure thingy. Press to inflate, let go to read current pressure - so simple, it works 100% of the time because it doesn't have any of that fancy electronic bullshit. Sadly these type of air filling stations are getting far and few between.

crazybigal
22nd January 2007, 12:22
you should go back and tell the fuckers! some poor sod will fuck his nice new tyres cos he thought he had the right psi

imdying
22nd January 2007, 12:23
I rarely visit that BP station but since I was in the area ... I'll never go back there again.

I like stations which have the good old fashion self pressure thingy. Press to inflate, let go to read current pressure - so simple, it works 100% of the time because it doesn't have any of that fancy electronic bullshit. Sadly these type of air filling stations are getting far and few between.Those types are just as likely to be out if not more likely... go visit the Caltex on Wairakei road for a demo.

Go buy yourself a gauge, you're nuts relying on something a thousand other people have given the bash.

Kwaka14
22nd January 2007, 12:23
I've seen tubed tyres taken to about 90psi when trying to seat the bead on the rim, I definitely wouldn't want to ride a bike at much more than the reccomended tyre pressure as the tyres footprint on the road gets very small very quickly.....

Squeak the Rat
22nd January 2007, 12:27
Those types are just as likely to be out if not more likely... go visit the Caltex on Wairakei road for a demo.

Go buy yourself a gauge, you're nuts relying on something a thousand other people have given the bash.

Good advice. Use your own gauge, it saves worrying about whether this will happen. Even if you use the same gas station all the time and think you can trust it, all it takes is for some clown to damage it and next thing you know you've got 50psi in your rubber.

idb
22nd January 2007, 12:29
Never rely on the garage gauge.
Buy a little pencil one and keep it in your jacket pocket.

Wasp
22nd January 2007, 12:47
i always use the newest available highest quality air pump at gas stations

jrandom
22nd January 2007, 12:48
I wouldn't worry too much about blowing up a motorcycle tyre by unintentional overinflation at the local service station. Tubular bicycle tyres are often run at up to 220psi, and clinchers are usually rated to 120 or thereabouts. The word is that the maximum pressure rating printed on the tyre is typically half the expected blowoff pressure.

Barring manufacturing defects, I'd imagine that your average motorcycle tube and tyre would be at least as strong, in terms of maintaining its structure under internal pressure, as an ultra-lightweight bicycle racing tyre. So long as you're under 100psi, I doubt you'd have any reason to be worried, assuming you're not working with damaged rims or worn-out tyre carcasses.

McJim
22nd January 2007, 13:29
Barring manufacturing defects, I'd imagine that your average motorcycle tube and tyre would be at least as strong, in terms of maintaining its structure under internal pressure, as an ultra-lightweight bicycle racing tyre.

Not so sure - my experience of motorcycles and cars has led me to believe that they don't really make things to the same standard of finish as bicycle components. Remember with Record and Dura Ace we are buying identical componentry to the professionals. On motorbikes and cars we don't get motoGP and F1 quality stuff.

My 2c

dnos
22nd January 2007, 13:48
You should absolutely buy a pressure gauge. I got one from repco for twenty bucks and its pretty good, and bloody handy, just keep it in your pocket.
Some of those service station gauges are shocking, and its a lottery as to which ones are correct and which ones are wrong.

As for how much pressure your bike tyre will take - I sure as hell don't want to find out for you.

Flyingpony
22nd January 2007, 14:22
I've read about people getting killed when truck tyres explode. Whilst I doubt a bike or maybe a cage tyre could do that, they'll definitely cause some damage to your hearing, and probably make you jump 10 foot in the sky with fright.

One thing for sure, the bike did feel different to ride with an over inflated rear tyre. The front felt perfectly fine, after all, before hand it was in the low 20's and felt heavy. So discovering 33psi is acceptable IMHO, but the 48, was a shock.

Kickaha
22nd January 2007, 14:37
I've read about people getting killed when truck tyres explode.

Thats a fairly rare occurence and is normally caused by sloppy workmanship


Whilst I doubt a bike or maybe a cage tyre could do that, they'll definitely cause some damage to your hearing, and probably make you jump 10 foot in the sky with fright.

Even if they don't kill you (and they could) they can still cause serious injury

any guage you use is only as accurate as it's last calibration, we do ours yearly

jrandom
22nd January 2007, 15:38
Not so sure - my experience of motorcycles and cars has led me to believe that they don't really make things to the same standard of finish as bicycle components. Remember with Record and Dura Ace we are buying identical componentry to the professionals. On motorbikes and cars we don't get motoGP and F1 quality stuff.

I concur - I suspect that the production tolerances in a Dura-Ace groupset are far tighter than the drivetrain of your average Japanese motorcycle in the showroom.

(I won't bring Campag into this discussion - we're only talking about quality engineering, here.)

With regard to the ability of tyres to withstand internal pressure, though, I don't think that modern road/track tyres are likely to be crappier in terms of quality control or flimsier in design than race tyres; after all, there's probably only a 20-40kph difference in top speed between a brand new litrebike and a MotoGP machine going down the back straight of a given track.

I doubt that the symmetry and strength of rims, beads and carcasses vary significantly between a typical MotoGP race setup and high-end trackday/road wheels. In fact, given the bleeding-edge state of GP tyre development and the undoubted focus on weight reduction, I wouldn't be surprised if commercial sprotbike tyres were more likely to withstand internal overpressure.

McJim
22nd January 2007, 15:50
Fish - less of the campag abuse okay? :rofl:

We're discussing an FXR150 rear tyre here so I personally wouldn't compare that to a top end litre sprotbike tyre. (nothing against FXR150s mind - fitness for purpose after all)

I think the advice of getting his own pressure guage is sound.

jrandom
22nd January 2007, 16:24
We're discussing an FXR150 rear tyre here so I personally wouldn't compare that to a top end litre sprotbike tyre...

Plenty of FXR150 riders use the likes of MT75s, TT900s or BT39SSs, all of which stack up quite nicely against Diablos or BT014s in the quality department.

Tyres are the absolute last thing I'd ever skimp on, regardless of bike size, and tyre manufacturers do offer a range of expensive, high-quality tyres in smaller widths, so I personally would compare an FXR150 rear tyre to a top end litre sprotbike tyre.

(Campag sucks)

Flyingpony
23rd January 2007, 07:51
Tyres are the absolute last thing I'd ever skimp on, regardless of bike size, and tyre manufacturers do offer a range of expensive, high-quality tyres in smaller widths, so I personally would compare an FXR150 rear tyre to a top end litre sprotbike tyre.
I agree ... I view my FXR 150 as being a learning ground in how to ride & maintain a large capacity motorcycle, but at a much cheaper rate. Once Mr Wallet is okay, I'll make the jump and know how to do stuff properly (at least I hope so). Also, if I make a simple mistake with the FXR now i.e. not maintaining chain properly, it's doesn't cost as much i.e. $63 o-ring chain.