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Rented or serviced motorcycles - suggestion


The Snark

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Me and my calibrated tire pressure gauge recently went on an outing. I checked the air pressure in the tires of around 15 rental places and about 10 repair fix-it shops including a Honda dealership. Pressure in the tires went from about 1 to 84 PSI. Average tire pressure, 12. Most modern motor bike tires look inflated around 5 PSI.

 

A few days back I observed an elderly local air up his tires then took off out of the station, nicely overloaded. A couple of dodges of vehicles and he lost control and went down. I helped pick him up, had a chat and he let me check the pressure in his tires. 3 and 5 PSI.

 

Do yourself a favor. Connect the dots. Try to move the survival odds into your favor wherever possible.

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I check my tire pressures once a week, and have them at 30 psi.

Scooters with metal spoked wheels seem to lose pressure faster than the ones with the carbon fibre composites.

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2 hours ago, Lacessit said:

I check my tire pressures once a week, and have them at 30 psi.

Scooters with metal spoked wheels seem to lose pressure faster than the ones with the carbon fibre composites.

I agree one should check car & bike tyre pressure regularly.  I could be wrong but I think non spoke wheels are more likely to be alloy & not carbon fibre. I stand to be corrected.

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1 hour ago, malt25 said:

I agree one should check car & bike tyre pressure regularly.  I could be wrong but I think non spoke wheels are more likely to be alloy & not carbon fibre. I stand to be corrected.

I think we're both right, alloy and carbon fibre. I'll yield on the relative percentages.

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It's not about metal vs carbon fiber, it's about tubed vs non-tubed. Tubed tires usually lose air quicker. Spoked wheels usually come with tubed tires (there are exceptions).

 

But coming back to the main point of the topic: yes, the right tire pressure is quite important for handling (safety) as well as lifetime of the tire. The vast majority of motorbikes in Thailand have very wrong tire pressures and if you go to one of the small repair shops where they fill up the air for you, they usually have a hose without any way to tell what the actual pressure is and just go by feel. Some gasoline stations have tire pressure fill up places with a gauge or a way to set the desired pressure. I bought a little air pump which comes with a gauge from http://www.pandarider.com/panda/Product_MotoPumps.htm

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From my experience if one of these small motorbike shops refills air they tend to put about 60-70 PSI in the tires. The average Thai then waits until the tire reaches 10 PSI and goes to refill it.

I also got a small electric pump, so i can put in the correct tire pressure by myself

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Very very few places in Thailand have air pressure gauges. Those that do, service stations, usually have the automated Waptool air compressor which appears to give +/- 10-15%.

 

Trivia:

Common tires and tubes loose air pressure because the material they are made from is slightly air transparent. This is the reason critical application tires such as those on airplanes are filled with nitrogen.

 

6 hours ago, Kwasaki said:

Has it been calibrate tested.

Yes. I used the bio-med equipment, mercury column, at a hospital a friend works at. ?

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26 minutes ago, The Snark said:

 

Trivia:

Common tires and tubes loose air pressure because the material they are made from is slightly air transparent. This is the reason critical application tires such as those on airplanes are filled with nitrogen.

That's wrong. The reason they use nitrogen in tires of airplanes, race cars and so on is that it reduces the risk of causing a fire. The advantage for regular car tires is marginal and was just introduced to make money (air consists of 78% nitrogen anyway)

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yes and you will be greeted with a little bit of contempt when you produce your air pressure gauge to check what they have done.

 

That is why I do the whole process myself at the local shop so no ones feelings get hurt.

 

NOT ONCE, with the exception of Kawasaki have I seen a air gauge in any shops. 

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11 hours ago, The Snark said:

Me and my calibrated tire pressure gauge recently went on an outing. I checked the air pressure in the tires of around 15 rental places and about 10 repair fix-it shops including a Honda dealership. Pressure in the tires went from about 1 to 84 PSI. Average tire pressure, 12. Most modern motor bike tires look inflated around 5 PSI.

 

A few days back I observed an elderly local air up his tires then took off out of the station, nicely overloaded. A couple of dodges of vehicles and he lost control and went down. I helped pick him up, had a chat and he let me check the pressure in his tires. 3 and 5 PSI.

 

Do yourself a favor. Connect the dots. Try to move the survival odds into your favor wherever possible.

I have to admit my approach is not very scientific but it works: Whenever I feel that the steering is not as accurate as it should be then it's time to look at the tire pressure. And there is the feeling in the bud if the rear pressure is not enough - I don't know if there is a scientific term for that.

 

I use this "system" since years in Bangkok. If I would go on a long trip then I would probably check the pressure properly before that trip (together with fluid levels, chain, etc.)

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Mentioned numbers in the OP of 3 to 5 psi are confusing me.

Typo?

 

As others wrote around 30 psi is OK.

As far as I remember the Honda dealer where I got my 110 ccm Wave told me 28 psi.

I check pressure with some 75 Baht mechanical "stylus" on car and motorbike.

Comparing pressure at filling stations shows that the deviation is below 2 psi.

It took me a while to get used to this non metric unit in mostly metric Thailand.

 

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Always check pressures when the tyres are cold. A trick I use after my sunday rides is to over fill the tyres on the way home at a filling station. Then after the bike and tyres have cooled down at home, I then check presures and release air.

 

Motorcycle tyre pressures, as a quick rule of thumb will rise 4-5 psi when at working temp. I've run pressures of 28 psi to 38 psi in my front tyres depending on the type of road riding I do and the tyres used. I like about 36-40 on the rear depending on conditions and tyre side wall stiffness.

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For myself, this air pressure thing is personal. Cruising up Angeles Crest highway on my tricked out Norton 850. Snugging into a curve hard and I felt that weird lateral shift of balance. As I reasoned later, the rear tire had picked up a nail or something, partly folded sideways, the fold grabbed much harder than the even curve of the tire would have, then traction broke. Luckily I had a high berm to slide into and didn't go over the edge. If I had been on one of those high CoG 4 banger monster bikes it would have been a couple hundred feet trip down into Switzer canyon. The tire still had enough air to get me back down into town. Didn't take much air loss to change the entire way the bike handled.

 

With the new style motorcycle tires, massive curved tread area and minimal sidewall they appear to be much more tolerant of incorrect tire pressure. Completely uninflated tires still stand up somewhat instead of looking like a squashed plum.

 

11 hours ago, OneMoreFarang said:

I have to admit my approach is not very scientific but it works: Whenever I feel that the steering is not as accurate as it should be then it's time to look at the tire pressure. And there is the feeling in the bud if the rear pressure is not enough - I don't know if there is a scientific term for that.

Seat of your pants steering? Pro race riders can tell if a tire is just a few pounds off.

 

12 hours ago, NCC1701A said:

yes and you will be greeted with a little bit of contempt when you produce your air pressure gauge to check what they have done.

That is why I do the whole process myself at the local shop so no ones feelings get hurt.

NOT ONCE, with the exception of Kawasaki have I seen a air gauge in any shops.

Happens every time I pull out my gauge. Weird farang.

 

12 hours ago, jackdd said:

That's wrong. The reason they use nitrogen in tires of airplanes, race cars and so on is that it reduces the risk of causing a fire. The advantage for regular car tires is marginal and was just introduced to make money (air consists of 78% nitrogen anyway)

I stand partially corrected, and my info came from a pro changing a tire on a B-17 doing an air show tour. Components in the air do leak through normal tires. But more importantly, Nitrogen doesn't expand and contract as readily as air, and the investigation of an aircraft crash determined the oxygen in the tires combined with chemical compounds that created a flammable gas and caused the tire to explode.

 

Be all that as it may, minimizing all possible hazards on the deadly roads of Thailand is always in order. Assume those bikes around you are unsafe and more than happy to take you down with them when they crash. And, for craps sake, don't become complacent and drive like the locals. Maintain that safety zone around you. We aren't in Kansas anymore, Toto.

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9 hours ago, Farangwithaplan said:

Motorcycle tyre pressures, as a quick rule of thumb will rise 4-5 psi when at working temp.

Back in my racing days we went with the 10 percent rule. Hot pressure 110 percent of cold pressure. Those that rode harder, and heated tires up more, started with a lower pressure.

Of course nowadays with radials and the huge leap in Tech, manufacturers numbers rule. They even visit race tracks now, give advice on pressure for individuals.

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13 hours ago, KhunBENQ said:

Mentioned numbers in the OP of 3 to 5 psi are confusing me.

Typo?

 

As others wrote around 30 psi is OK.

As far as I remember the Honda dealer where I got my 110 ccm Wave told me 28 psi.

I check pressure with some 75 Baht mechanical "stylus" on car and motorbike.

Comparing pressure at filling stations shows that the deviation is below 2 psi.

It took me a while to get used to this non metric unit in mostly metric Thailand.

 

I guess you mean "bar" which I don't like not enough room for adjustment ? I mean my motorcycle tyres are 22 psi which is 1.5168466015999806 bar. ?

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17 hours ago, jackdd said:

That's wrong. The reason they use nitrogen in tires of airplanes, race cars and so on is that it reduces the risk of causing a fire. The advantage for regular car tires is marginal and was just introduced to make money (air consists of 78% nitrogen anyway)

OP is not exactly wrong there are several reasonable compelling reasons for enthusiasts to use pure nitrogen and you state one indirectly yourself in what's left the 20 % oxygen & water vapour plus other gases in the tyre.

Another is that nitrogen escapes through tyre rubber much slower than oxygen. 

Also another motoring forum topic done to death with pro et contra. ?

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