Add this to the spares that you carry -- tire valves

[paulcbrowne]

I has to be over 40 years since one of these failed on me but tonight I had an OEM tire valve fail to hold air when I was filling my from tire and removed the air chuck. No tapping or probing with a small screwdriver would get it to seal. I routinely carry a small assortment of wire, tape, fuses, bungies, tire plugger, pump; but this is one part I never thought of.

 

This one almost smacks of Richard the Third's "... for lack of a nail...."

[ShovelStrokeEd]

So your gonna carry a bead breaker and a set of tire irons with you as well? Only way to get the new one in is from the back. Too low a failure rate to worry about. Worst comes to worst, you can probably over-inflate, slap the valve cap back on and limp to civilization. You do use a metal valve cap with an internal seal, right?

[Roger_R]

Why???? Every car has at least 4, 5 if you count the spare. There all over, go get one. Just make sure you don't get caught

 

Not a bad idea though, have a few rolling around in the toolbox, does'nt take up much space.

[ESokoloff]

Only way to get the new one in is from the back. ......

You do use a metal valve cap with an internal seal, right?

 

Ed, he's referring to just the core not the entire assembly.

On my wife's cage I recently found two valve cores to be defective/leaking.

IMHO the cores are the primary seal & the caps just keep things clean & slow down the leak. It was in this case.

 

 

Not a bad idea to add a spare or two cores to your tire repair kit. Make sure you also have a tool to remove/install them. Might as well throw in a few caps too.

Chances are you wont need the cores but cheep insurance to have them.

Thanks for the tip

[duckbubbles]

I had that happen to me somewhere in the Carolinas a few years back. The good news was it happened while putting air in at a gas station. I was able to borrow a valve core removal tool from the station, took the core out and cleaned the little piece of crap out of it.

I've also seen the tip of them get bent from the service station filler nozzles, especially with trying to get the filler into the wheel with big discs and many spokes. They can be removed and straightened most of the time.

90 deg. valve stems can help this. I've been warned by a tire rep not to install them. His reasoning was that something can hit the stem and break it off. That would be catastrophic. But I'll take my chances. I'm not talking about the 90 degree elbows that screw onto the existing valve stem- I mean the actual valve stem made that way. Stay away from the "adapters".

I've also seen the tire pressure monitoring valve caps leak. These are the ones you buy with a specific pressure range and screw them on. While you have a green thing visible in the clear window in "theory" you are ok.

 

Frank

[ShovelStrokeEd]

Eric,

Actually the valve stem cap IS the primary seal. It seems to be secondary while looking at the circuit but the Schraeder valve is subject to some pretty good forces, tending to open it, at high speeds and really should not be relied upon as a primary seal. This is the reason ALL racing organizations insist on metal valve caps and they really should be have a gasket.

[ESokoloff]

Actually the valve stem cap IS the primary seal.

 

My experience with Schrader valves comes primarily from 23 years in the service aspect of the HVAC industry.

In that industry the core is the primary seal, the cap is the secondary seal.

My thoughts are the same for any field that they are used, IMHO.

 

My wife's 2005 BMW 645ci dealer serviced cage is a perfect example of this belief.

The caps are the same or comparable to the ones used on current model BMW bikes yet they did not hold.

 

 

Of course you are entitled to your thoughts on this issue

[ShovelStrokeEd]

Tire application is not HVAC. They very rarely spin their piping and subject the valves to centrifugal force.

[BucksTherapy]

In high speed racing the centrifugal forces are such that they will open most Schrader valves installed at 90 degrees to the road road surface(aligned with the centrifugal force).

 

Thsi can also happen on our bikes when we get carried away. This is the advantage to the brass valve assemblies that turn the stem to be parrallel to the road surface(90 degrees away from the centrifugal force).

 

The turned stems in combination with the metall valave caps with the rubber o-rings are you best combination for maintaining air pressure in your tire.

 

One mroe option with several advantages is have the tires inflated with Nitrogen. Many tire shops now offer this for under $10 a tire. This allows the tires to run cooler, have less pressure variance due to temp changes and the larger molecules tend to result in less pressure loss over time. In addition the Nitrogen does not rust rims or oxidize tires. Finally you get those pretty green valve caps to signify they are filled with Nitrogen.

 

Many high speed racers have gone to nitrogen for more consistent preformance as tires heat up.

 

Lots of options.

[ESokoloff]

I thought Mitch had put this thing to bed

[BucksTherapy]

I didn't see anything about nitrogen so had to add my $.02

[ShovelStrokeEd]

That's why they are called legends, Eric.

 

Three statements in one post concerning Nitrogen in tires and all with no basis in fact. Sheesh!

[Jim VonBaden]

That's why they are called legends, Eric.

 

Three statements in one post concerning Nitrogen in tires and all with no basis in fact. Sheesh!

 

Or myths!

 

Jim

[Martyn]

Eric,

Actually the valve stem cap IS the primary seal. It seems to be secondary while looking at the circuit but the Schraeder valve is subject to some pretty good forces, tending to open it, at high speeds and really should not be relied upon as a primary seal. This is the reason ALL racing organizations insist on metal valve caps and they really should be have a gasket.

 

On a tour of the Avon tyre factory a few years ago, the techie. showing us around made just this point. He also made the point re a metal cap with a seal inside. As it's his job, I have ever since taken it as good advice.

[BucksTherapy]

That's why they are called legends, Eric.

 

Three statements in one post concerning Nitrogen in tires and all with no basis in fact. Sheesh!

 

Awful lot of folks wiht a bunch of letters after their names disagree with you.

 

http://getnitrogen.org/

 

I am not a chemicla engineer or a chemist but I tend to believe given the improvement in performance on my bike. Mileage and handling improved. I haven't taken tire temps with and without so can't comment on temp.

 

Cheers

[ShovelStrokeEd]

OK, let's get specific.

 

Nitrogen changes pressure with temperature at exactly the same rate as any other gas or all other gases for that matter. There are some minor variations to that when dealing with temperatures at the critical point, non-ideality is the term, but I doubt we will be doing much riding/driving at 77 degrees Kelvin (-321.6 deg F).

 

While it is true that Nitrogen will permeate more slowly through rubber than will air (which contains both Oxygen and Argon molecules as the main other components), however, the difference in pressure with time will not be measurable in your lifetime. The difference in the atomic radius between O2 and N2 may be inferred from the Van der Wahl radius of the two atoms. N2=1.55 angstrom, O2=1.53 angstrom. One Angstrom=1.00x10e-7 mm. Not very big, is it?

 

Tire running temperature has nothing whatever to do with the gas used to inflate the tires, only with the degree of inflation. It doesn't even have very much to do with the road temperature. Most of the heating in the tire comes from the hysteresis of the rubber during flexure and at the tread from friction with the road surface. Tires lose heat by radiating it out to the surrounding air not by transfer of heat to the wheel and, when it comes to thermal transfer, Nitrogen is no different from air.

 

I am neither a chemical engineer nor a chemist either but the scientific instruments with which I work use these principles as their basis of operation and I have spent a good deal of time and effort learning the gas laws. You might benefit from similar study.

 

To carry on with some of the stuff spouted by the non-biased site you quoted, everything they say is true. However, this stuff is a matter of degree.

 

Oxygen will cause rubber to break down but, it is ozone that does the really nasty stuff and again, it takes years. I get about 4 months out of a set of tires, not much to worry about there. They may well have sat on a dealer's shelf for that long.

 

Water vapor is a factor but, until you get to really high levels, it has minimal effect. Liquid water is another matter and can have a large effect on the tire pressure change with temperature. You would be better served paying strict attention to what bead lubricant your tire changer uses and how it is applied than worrying about what he used to inflate the tire. When it comes to compressors, yes, water vapor will be concentrated in the compressor during the compression cycle but, it condenses back out and falls to the bottom of the reserve tank when the air cools back down in the tank. Not an issue unless you use one of those little inflater tools to fill your tires and live, as I do, in Florida, where, on a good day, the RH exceeds 60% and can reach 95%.

 

Rim corrosion is not a factor on motorcycles with their alloy rims. I would take precautions with magnesium rims. Even the steel rims on my '48 HD are painted and, unless the paint, or chrome, is compromised by scratches and such, the coating will serve as all the corrosion protection you need.

 

BTW, the race teams inflate their tires with Nitrogen cause it is easily transportable in those big tanks. They also use if for their air tools for the same reason. There is a bit of a safety factor as well as they use nearly 250 PSI to get the air flow through the hose on those fast air guns and a big compressor tank at 250 PSI is not the kind of bomb you want in your pit area.

[aggieengineer]

Hey, maybe there's some money yet to be made here. I think I'll design a vacuum tank that can hold a wheel and be fillable with nitrogen after pumping down. That way, we could get rid of the 1 atmosphere of nasty old air that is always in the tire prior to inflation with nitrogen. I knew that engineering degree would make me wealthy one day!

 

PV=nRT

[BucksTherapy]

OK I'm convinced. I agree that most the improvements provided by nitrogen are real but negligible.

 

The one point I can not confirm is the effect of a small change in the size and weight of the atoms involved. Depending on the spacing of the molecules in the rubber the flow rate of the gas through the rubber could be effected by a ratio exceeding that of the ratio of the differences in the atom size. Did I say what I mean?

 

In other words the 2% difference in atom size could produce somewhat more then 2% difference in flow rate. I have no idea if this could allow for the six times as much loss with air as I have not seen any scientific testing to confirm or debunk.

 

The theory put forward for temp difference is based on moisture being present in air and working its way into the rubber. Filling the voids in the rubber with moisture would increase the mass and potentially friction during the flexing of the rubber. The theory seems logical but again it is questionable if the claims of temp differences significant enough to effect the life of tire have not been validated.

 

I agree that the conclusions of significant improvements in gas retention and heat reduction have not been proven.

 

I would like to see the results from testing over time and temp performance under controlled conditions. I am certain some university thesis will adress this as it is a relatively simple set of experiments.

 

As is the case most of the time the truth probably lies between no affect and dramatic affect. It is a matter of degrees as you have said.

 

Membranes and flow rates are not my area of expertise but this is an interesting discussion.

[Boffin]

I think that Mitch's encyclopedic post covers the subject with a scholarly depth and accuracy.

 

Andy

[ShovelStrokeEd]

Sure does and he has both the tools and the skilz to back it up.

[Joe Frickin' Friday]

Awful lot of folks wiht a bunch of letters after their names disagree with you.

 

If those letters are "MBA," and they work for a business entity (www.getnitrogen.org) whose purpose is to bolster the popularity of nitrogen among consumers, then their motivation is suspect.

 

I have letters after my name too (BS, MS, Ph.D in mechanical engineering), and after much digging I concluded that nitrogen won't make a rat's ass worth of difference for the average consumer.

 

 

EDIT: posted this before I saw page 2 of this thread; looks like my post has already been referenced.