OTT Thai tire pressures...

[ChiangmaiRob]

It's no hassle, compressor and tools are carried in a small Ocean waterproof pack, just imagine what a nightmare it would be should you experience a puncture on a big bike, you would either have to call breakdown people and who knows how long that would take, flag down a pick-up or lorry who's occupants would probably not speak your language, ask them some how to help transport your big bike to a garage, whereas I can fix a puncture in minutes and be on my way.

Agreed, but you're talking big bikes but I'm only talking scooters. For long distance, I take the truck.

[ChiangmaiRob]

My Nuvou scooter with wire rims and tubed tire has flats every couple months or more.

My honda with alloy rims and tubeless had zero flats last year.

I've always had alloys on my scooters, for two reasons; they look better than spoked rims and on quite a few occasions I've had friends get punctures with spoked rims when they hit a pothole and the rim distorted enough to make the spoke go slack inside the rim and puncture the tube.

[jacko45k]

I don't think it affects the number of flats. I know if I over inflate the rear one , I will have a bad back soon.

[papa al]

ImageUploadedByThaivisa Connect Thailand1418107147.393133.jpg

In this bag is the air compressor, tire gauge, cloth, galvanizing solution, plugs and knife, tools are carried in my tank bag, no problem at all, why drive many Kms with a flat when you can fix a puncture in minutes.

What is galvanizing solution?

[ChiangmaiRob]

RE Post #21

Nitrogen expands when heated as do all gasses including the atmospheric mix => air (69% nitrogen).

Remember from high school chemistry Boyle's law of perfect gasses:

PV/T=k

Pressure x Volume divided by Temp (Kelvin) is constant.

Volume in the filled tire is pretty constant, so if T goes up, P goes up proportionately.

Correct but the pressure change is much less with N2 than it is with air and the N2 it's dry whereas the air is water wet, which also affects the pressure.

[Badrabbit]

ImageUploadedByThaivisa Connect Thailand1418107147.393133.jpg

In this bag is the air compressor, tire gauge, cloth, galvanizing solution, plugs and knife, tools are carried in my tank bag, no problem at all, why drive many Kms with a flat when you can fix a puncture in minutes.

What is galvanizing solution?

Sorry should read Vulcanizing cement or rubber cement, the stuff I have is called Monkey grip from the USA. Edited December 9, 2014 by Badrabbit

[ChiangmaiRob]

ImageUploadedByThaivisa Connect Thailand1418107147.393133.jpg

In this bag is the air compressor, tire gauge, cloth, galvanizing solution, plugs and knife, tools are carried in my tank bag, no problem at all, why drive many Kms with a flat when you can fix a puncture in minutes.

What is galvanizing solution?

I think he means vulcanising solution but It's basically a solvent based adhesive for bonding rubber plugs or patches to the tyre or tube.

[Badrabbit]

ImageUploadedByThaivisa Connect Thailand1418107147.393133.jpg

In this bag is the air compressor, tire gauge, cloth, galvanizing solution, plugs and knife, tools are carried in my tank bag, no problem at all, why drive many Kms with a flat when you can fix a puncture in minutes.

What is galvanizing solution?

I think he means vulcanising solution but It's basically a solvent based adhesive for bonding rubber plugs or patches to the tyre or tube.

Spot on.

[Shurup]

RE Post #21

Nitrogen expands when heated as do all gasses including the atmospheric mix => air (69% nitrogen).

Remember from high school chemistry Boyle's law of perfect gasses:

PV/T=k

Pressure x Volume divided by Temp (Kelvin) is constant.

Volume in the filled tire is pretty constant, so if T goes up, P goes up proportionately.

Correct but the pressure change is much less with N2 than it is with air and the N2 it's dry whereas the air is water wet, which also affects the pressure.

Doesn't matter which gas you use, pressure change would be the same with any gas. It's basic physics buddy so don't argue if you were skipping the physics classes in high school.

And regarding your comment about the "wet" air, there's virtually no water in that small air volume inside the tire, not enough to make any difference, and even IF there was a significant amount of water, the effect on the tire pressure would be opposite of what you think. Water volume change very little with the change in temperature so if part of the tire air volume is occupied by water, it means less pressure change with temperature change.

[how241]

I would actually drop a couple of psi on my CBR 250 before heading out on my long trips, where I'd be riding hard for 4-6 hours.

When I bought new Michelin's to go on, I brought my own tire gauge and, sure enough, they had over inflated the recommended pressures clearly stamped on the side walls. I don't think they even know there is a recommended pressure stamped on the tire walls, and just pump in the air till it "feels right".

Most just go by how it 'feels'.

[ttakata]

Higher pressure on a bike increases fuel economy but reduces the size of the contact patch so less grip and more chance of losing grip.

I put about 5psi more than the bike recommends since I don't ride aggressively on a scooter.

After 1 month, my tubeless end up 3psi lower than the recommended psi.

[MrY]

On the subject, my tyres deflate slowly over three weeks down to about 15 psi. Happens on all six wheels of my three bikes.

Have I somehow picked up a batch of bad valves or is this normal?

Mine every 2 weeks....

I already had countless punctures due to deflated tyres. Never happened to me in my country.

I guess it happens because of the poor inner tubes quality..... they are really cheap, aren't they?

Poor quality inner tubes, poor quality tires and poor quality mechanics who wack in as much air as humanly possible! Saying that I have had very few flat tires but do get the air loss over a week maybe, it's very easy to let the air out after the mechanic has had a rush of blood to his head and tried to put hundreds of psi in!

In my experience most local tire guys will inflate the new tires to near 60 psi. Over-inflating the tires will cause air to find paths through the inner tube and will ruin it permanently (I suspect some of these 'mechanics' are fully aware of this, but hey, fixing flats is what they make money out of). After a few days (?) lowering the pressure to recommended values will not help, the tube will always leak. The high pressure helps them seat the tire bead on the rim, but should be let out immediately. I carry a pop-out style tire pressure gauge [that I've checked for accuracy] and always immediately check the pressure right after they are inflated by anyone without a pressure gauge (that is to say, anyone).

Using 35 psi for the front and 40 psi for the rear on my scooter, if I'm gone 3-4 months away from my bike there's still enough pressure left to drive slowly to the fill station. In 22 years I have never had a puncture I could not find an external reason for. Any inner tube that leaks gets replaced immediately and any tire that has been driven flat never gets re-used.

Hope this helps.

[papa al]

RE Post #21

Nitrogen expands when heated as do all gasses including the atmospheric mix => air (69% nitrogen).

Remember from high school chemistry Boyle's law of perfect gasses:

PV/T=k

Pressure x Volume divided by Temp (Kelvin) is constant.

Volume in the filled tire is pretty constant, so if T goes up, P goes up proportionately.

Correct but the pressure change is much less with N2 than it is with air and the N2 it's dry whereas the air is water wet, which also affects the pressure.

No.

N2, O2, H2, CO2, H2O, NH3, CH4, CCl4, argon, helium,... all gasses change the same.

Please consult some basic chemistry resource to verify this.

Edited December 9, 2014 by papa al

[canuckamuck]

They delivered me a new quad last week. Took it for a spin on the blacktop and was shocked that it shook and shimmied down the road. I took a look at the tire pressure and they had them at 32 PSI although the tires were rated for 5. That fixed some of the shaking. I got the rest sorted when I realized they hadn't tightened the lug nuts on the right rear. I am quite pleased with it now.

I told the lady at the shop about the correct air pressure today, she looked at me like I was discussing the weather and changed the subject.

It is no wonder they have trouble selling these things here.

[MrY]

RE Post #21

Nitrogen expands when heated as do all gasses including the atmospheric mix => air (69% nitrogen).

Remember from high school chemistry Boyle's law of perfect gasses:

PV/T=k

Pressure x Volume divided by Temp (Kelvin) is constant.

Volume in the filled tire is pretty constant, so if T goes up, P goes up proportionately.

Correct but the pressure change is much less with N2 than it is with air and the N2 it's dry whereas the air is water wet, which also affects the pressure.

No.

N2, O2, H2, CO2, H2O, NH3, CH4, CCl4, argon, helium,... all gasses change the same.

Please consult some basic chemistry resource to verify this.

...or physics.

The first thing you learn about the Ideal Gas Law is that it is not actually true and correct for all temperatures and pressures, but it does represent the properties of gases we deal with quite closely.

Nitrogen has it's minute advantages, mostly for aviation and racing. It is also quite cheap per bottle, thus quite profitable to sell as a miracle fix for your tires. There is no practical or cost efficient advantage for using it. Buy an air pressure gauge for the money.

[ktm jeff]

Nitrogen molecules are larger than air molecules , (and less hydroscopic) , so its more difficult for them to leak out . This maintains the correct pressure for longer. The main advantage.

[MrY]

...and air, as mentioned before, is already 80% nitrogen. What advantage there is in changing the less than 20% oxygen content to a slightly less leak prone gas is minute indeed. The quality of the tire [and possibly inner tube] and how it is installed (bead seal) plays a much bigger role. Some shops have advertised free nitrogen fill with tire purchase, but you'd have no way of knowing what goes into your tire unless you fill it from your own bottle. I have a nitrogen bottle at home but I use it for my wines, not my tires...

[CarlTyson]

My stock Honda SH150 tires leak very little. About 1Lb of pressure per month.

Very pleased.

[biplanebluey]

High pressure is great if you are hauling 3 or 4 people.

Or even 2 really big ones.

And for increased fuel economy.

For 5 baht you can get 30psi, or 60psi.

No brainer!!

Tyres are designed by people in the manufacturing industry----that know what they are doing------ to run at a certain pressure to give you max wear.You don't pump them up (TO60PSI !!!!} just cos you have a fat idiot in the car----- NO BRAINER

[biplanebluey]

My Nuvou scooter with wire rims and tubed tire has flats every couple months or more.

My honda with alloy rims and tubeless had zero flats last year.

I've always had alloys on my scooters, for two reasons; they look better than spoked rims and on quite a few occasions I've had friends get punctures with spoked rims when they hit a pothole and the rim distorted enough to make the spoke go slack inside the rim and puncture the tube.

Are you joking?????--------- Have you ever seen the "blunt" end of a spoke that's inside the rim ???

[yankee99]

High pressure is great if you are hauling 3 or 4 people.

Or even 2 really big ones.

And for increased fuel economy.

For 5 baht you can get 30psi, or 60psi.

No brainer!!

Tyres are designed by people in the manufacturing industry----that know what they are doing------ to run at a certain pressure to give you max wear.You don't pump them up (TO60PSI !!!!} just cos you have a fat idiot in the car----- NO BRAINER

Never looked on bike tire but my car/truck tires had a load (weight) rating on them. Didn't mention changing air pressure with different loads.

[yankee99]

My Nuvou scooter with wire rims and tubed tire has flats every couple months or more.

My honda with alloy rims and tubeless had zero flats last year.

I've always had alloys on my scooters, for two reasons; they look better than spoked rims and on quite a few occasions I've had friends get punctures with spoked rims when they hit a pothole and the rim distorted enough to make the spoke go slack inside the rim and puncture the tube.

Are you joking?????--------- Have you ever seen the "blunt" end of a spoke that's inside the rim ???

Same issue flat and bent rim with the spokes loosening... 6000 baht for mags problem solved.

[CarlTyson]

High pressure is great if you are hauling 3 or 4 people.

Or even 2 really big ones.

And for increased fuel economy.

For 5 baht you can get 30psi, or 60psi.

No brainer!!

Tyres are designed by people in the manufacturing industry----that know what they are doing------ to run at a certain pressure to give you max wear.You don't pump them up (TO60PSI !!!!} just cos you have a fat idiot in the car----- NO BRAINER

Never looked on bike tire but my car/truck tires had a load (weight) rating on them. Didn't mention changing air pressure with different loads.

I would add 10% to the rear tire if I had a pillion.

[WitawatWatawit]

On a previous thread I was told you could not fit tubeles tyres to a Scoopyi. I did try to talk to the shop I bought the bike from about changing the rims, but because I wasn't immediately splashing cash around, they gave me the brush off (hate that). I'll try again with another shop as I'm sick of the punctures - but before I do, does anyone have any pointers?

BTW, had to put a new tyre and tube on the rear the other day (700 baht), then got home and checked the air pressure. It was 60psi as against 33 recommended on the tyre. Why is there such a reluctance to use a pressure gauge?

Also, I was wondering about the frequent separation of the valve from the tube. Could it be because the outside holding nut is not done up tight enough? Since I made a point of checking this and tightening the nut, I've had fewer problems.

Edit for typos.

Edited December 10, 2014 by WitawatWatawit

[Badrabbit]

On a previous thread I was told you could not fit tubeles tyres to a Scoopyi. I did try to talk to the shop I bought the bike from about changing the rims, but because I wasn't immediately splashing cash around, they gave me the brush off (hate that). I'll try again with another shop as I'm sick of the punctures - but before I do, does anyone have any pointers?

BTW, had to put a new tyre and tube on the rear the other day (700 baht), then got home and checked the air pressure. It was 60psi as against 33 recommended on the tyre. Why is there such a reluctance to use a pressure gauge?

Also, I was wondering about the frequent separation of the valve from the tube. Could it be because the outside holding nut is not done up tight enough? Since I made a point of checking this and tightening the nut, I've had fewer problems.

Edit for typos.

Scoopyi come in two forms, one has tubed tires the other has tubeless tires, my gf has the Scoopyi with tubeless tires, I see no reason why you would not be able to buy new wheels with tubeless tires, as for the tube separating at the valve it's poor quality tubes and massive over inflation! it's far easier for these mechanics to wack in loads of pressure then hit the tire with a spanner, if it bounces off with a twang it is perfect for them! If a new tube gets 60psi it's probably been weakened, best to make it clear to the mechanic before he gets the chance to wack in loads of pressure that you only want 33psi rear and 30psi front! Edited December 10, 2014 by Badrabbit

[papa al]

High pressure is great if you are hauling 3 or 4 people.

Or even 2 really big ones.

And for increased fuel economy.

For 5 baht you can get 30psi, or 60psi.

No brainer!!

Tyres are designed by people in the manufacturing industry----that know what they are doing------ to run at a certain pressure to give you max wear.You don't pump them up (TO60PSI !!!!} just cos you have a fat idiot in the car----- NO BRAINER

Subtle humor evades many.

[papa al]

On a previous thread I was told you could not fit tubeles tyres to a Scoopyi. I did try to talk to the shop I bought the bike from about changing the rims, but because I wasn't immediately splashing cash around, they gave me the brush off (hate that). I'll try again with another shop as I'm sick of the punctures - but before I do, does anyone have any pointers?

BTW, had to put a new tyre and tube on the rear the other day (700 baht), then got home and checked the air pressure. It was 60psi as against 33 recommended on the tyre. Why is there such a reluctance to use a pressure gauge?

Also, I was wondering about the frequent separation of the valve from the tube. Could it be because the outside holding nut is not done up tight enough? Since I made a point of checking this and tightening the nut, I've had fewer problems.

Edit for typos.

Scoopyi come in two forms, one has tubed tires the other has tubeless tires, my gf has the Scoopyi with tubeless tires, I see no reason why you would not be able to buy new wheels with tubeless tires, as for the tube separating at the valve it's poor quality tubes and massive over inflation! it's far easier for these mechanics to wack in loads of pressure then hit the tire with a spanner, if it bounces off with a twang it is perfect for them! If a new tube gets 60psi it's probably been weakened, best to make it clear to the mechanic before he gets the chance to wack in loads of pressure that you only want 33psi rear and 30psi front!

Wabbit no wike wack in'.

Edited December 10, 2014 by papa al

[yankee99]

On a previous thread I was told you could not fit tubeles tyres to a Scoopyi. I did try to talk to the shop I bought the bike from about changing the rims, but because I wasn't immediately splashing cash around, they gave me the brush off (hate that). I'll try again with another shop as I'm sick of the punctures - but before I do, does anyone have any pointers?

BTW, had to put a new tyre and tube on the rear the other day (700 baht), then got home and checked the air pressure. It was 60psi as against 33 recommended on the tyre. Why is there such a reluctance to use a pressure gauge?

Also, I was wondering about the frequent separation of the valve from the tube. Could it be because the outside holding nut is not done up tight enough? Since I made a point of checking this and tightening the nut, I've had fewer problems.

Edit for typos.

I think what they might be saying is if you change your oem spoked rims to mags the oem tires are not rated for tubeless thus you need new tires, The scoopy unlike the nouvo has a wide selection of aftermarket mags at a reasonable price....

[MartinL]

RE Post #21

Nitrogen expands when heated as do all gasses including the atmospheric mix => air (69% nitrogen).

Remember from high school chemistry Boyle's law of perfect gasses:

PV/T=k

Pressure x Volume divided by Temp (Kelvin) is constant.

Volume in the filled tire is pretty constant, so if T goes up, P goes up proportionately.

Correct but the pressure change is much less with N2 than it is with air and the N2 it's dry whereas the air is water wet, which also affects the pressure.

No.

N2, O2, H2, CO2, H2O, NH3, CH4, CCl4, argon, helium,... all gasses change the same.

Please consult some basic chemistry resource to verify this.

...or physics.

The first thing you learn about the Ideal Gas Law is that it is not actually true and correct for all temperatures and pressures, but it does represent the properties of gases we deal with quite closely.

Nitrogen has it's minute advantages, mostly for aviation and racing. It is also quite cheap per bottle, thus quite profitable to sell as a miracle fix for your tires. There is no practical or cost efficient advantage for using it. Buy an air pressure gauge for the money.

I like physics/thermodynamics so I'm going to continue this subject even if it bores the pants off others.

But whatever we say, the reality is far more complex than there's space for discussion here. For example, pumping the same mass of two different gases into two identical tyres under the same conditions will result in different pressures.

PV/T = constant© is true but only for a specific gas and, more specifically, a homogeneous (100% pure gas, including "pure" air) so wet air doesn't obey this "Law" at all.

If that is transposed & expressed as PV = cT, then that "c" is made-up the mass of gas m, the Universal Gas Constant Ro (the same for all gases) and the Molar Mass, M (different for all gases) so that the equation becomes PV = m*(Ro/M)*T.

For a tyre, we can say that V is constant, mass m is constant, Ro is constant and, for a warmed-up tyre, T is constant.

Therefore the pressure in the tyre is inversely proportional to the Molar Mass, M. For any particular condition, a high Molar Mass ---> low tyre pressure.

M for nitrogen is 28. For air it's accepted to be about 29.

Therefore if you run two tyres under exactly the same conditions, one filled with air & the other with nitrogen, the one filled with air will have a lower pressure than the one with nitrogen, but it's marginal and probably not noticeable. If the air-filled tyre is at 100%, the nitrogen-filled tyre would be about 103.5% or 32psi v 33psi.

I have no explanation for the use of nitrogen to inflate tyres on roadgoing vehicles - except maybe as a moneyspinner as mentioned above or because larger molecules ---> lower leakage rates - but I'm pretty sure it makes not a bit of difference to road riders. Anyway, if my tyre loses pressure on a run, it's far easier to find an air pump/compressor than a bottle of compressed nitrogen.

Yaaaaaawwwwwnnnnn!!

OK, boredom session over. Wake up, readers.

[12DrinkMore]

I like physics/thermodynamics so I'm going to continue this subject even if it bores the pants off others.

But whatever we say, the reality is far more complex than there's space for discussion here. For example, pumping the same mass of two different gases into two identical tyres under the same conditions will result in different pressures.

PV/T = constant© is true but only for a specific gas and, more specifically, a homogeneous (100% pure gas, including "pure" air) so wet air doesn't obey this "Law" at all.

If that is transposed & expressed as PV = cT, then that "c" is made-up the mass of gas m, the Universal Gas Constant Ro (the same for all gases) and the Molar Mass, M (different for all gases) so that the equation becomes PV = m*(Ro/M)*T.

For a tyre, we can say that V is constant, mass m is constant, Ro is constant and, for a warmed-up tyre, T is constant.

Therefore the pressure in the tyre is inversely proportional to the Molar Mass, M. For any particular condition, a high Molar Mass ---> low tyre pressure.

M for nitrogen is 28. For air it's accepted to be about 29.

Therefore if you run two tyres under exactly the same conditions, one filled with air & the other with nitrogen, the one filled with air will have a lower pressure than the one with nitrogen, but it's marginal and probably not noticeable. If the air-filled tyre is at 100%, the nitrogen-filled tyre would be about 103.5% or 32psi v 33psi.

Jeeze, this is going back a few decades.

PV = nRT

n = mass in grams/Molar mass = number of moles which is a constant for a constant volume of gas.

I believe that you are looking at the Specific Gas Constant (Rs) which does change with the gas, although for most purposes the Universal Gas Constant ( R ) can be used.

I believe Rs = R / M.

So although the conclusion is true, the argument is not correct.

(However I could be wrong, this is pulling in stuff from a few decades ago....)

Wotcha fink?

Edited December 10, 2014 by 12DrinkMore