Tire inflation

[Top_Speed1]

Wow, a $26,000 Tire Pressure Monitoring System!! Whadda bargain!!!

Since I said with 50 other options, that makes the TPM = $520. I think my life is worth $520, maybe not $521 tho

 

[TomInPA]

So has the O.P. had to add air since this post? How much time had elapsed since it was previously checked?

We have seen guys post about low air pressure that ASSUMED the dealer or tire installer properly inflated tires. We have also seen tires lose pressure from contamination of the bead seal (label) and of course damaged tires and valves. I honestly thought this thread would end up in NEPRT almost immediately. It isn't that complicated, but without followup from the O.P. we can speculate forever.

 

[Top_Speed1]

To add to Tom's thoughts ^

If I have to have a tire (tyre) changed out in the field and a dealer does the service?... ALWAYS under-inflated (at least to my 40-42psi long life desires). They usually are low to mid 30's at least with my experience and I find a quicker wear in this range. May be why dealers do this as well? they after all are in the sell to you market.

 

[Bogus]

Just had a tire replaced by my non denominational service guy and the tire came back with 48#.

 

[jmgrif]

Not sure if I missed the time between pressure checks? I had one sudden loss of air pressure in my front tire caused by an angled valve stem of the rubber base with the bent pipe style! I found out rather dramatically that over time the centrifical force bends the valve stem and eventually the rubber weakens and tears where it is being pulled. Instant deflation at high speed, at first I thought I was being hit by a sudden strong gust of wind. I now have Ariette's! I did follow a friend who had picked up something in his back tire causing a slow leak while riding and as the tire gradually lost pressure the tire over heated and delaminated! No road side repair that time.

 

[Bill Lumberg]

Big change is normal if you live where there's a winter and summer. I check mine daily. But i ride almost daily.

 

[Pterodactyl]

Used to live in Fairbanks. Our garage was heated because we had a 300 gallon water tank in there. We had to keep it at 55 degrees or the furnace would not function. So imagine what it was like when we drove a car in or out in -45 degree weather. An instant 100 degree temperature change. We had to run nitrogen in the tires or the tire pressure system would go nuts.

 

[RichDoyle]

Used to live in Fairbanks. Our garage was heated because we had a 300 gallon water tank in there. We had to keep it at 55 degrees or the furnace would not function. So imagine what it was like when we drove a car in or out in -45 degree weather. An instant 100 degree temperature change. We had to run nitrogen in the tires or the tire pressure system would go nuts.

Even in places like Colorado. You get these cold fronts from Canada (Blame Canada...). 70F degrees at 11:00 AM, 0F by 6:00 PM and -20 the next morning.

But here's another factor nobody has mentioned: Make/model of tire. Let me 'splain:

My airplane (like most small planes) has tube type tires. The tires are Goodyear (wildly common). Tire pressures: 2.5 bar (36 psi) and 2.0 bar (29 psi) in the mains and nose wheel, respectively. The plane also came with Goodyear tubes. The compound Goodyear uses in their tubes is such that you had to add air every 2-3 weeks. I replaced these with Michelin tubes. Now it's months between needing to add air.

This is information that is not available to you when you buy tires for bikes. I don't know how one might find this out: What is the diffusion behavior of the tires you're buying?

To put some balance to all this: Your tires heat up while riding and the pressure therefore increases. AND for those who are traveling mountainous areas, there is a decrease/increase of roughly 1 psi for each 2,000 vertical feet one ascends/descends, respectively. Doesn't seem like a big deal unless you drove from Whidbey Island, WA to the top of the highway in Rocky Mountain National Park, like I did a couple of years ago. That's worth 7 psig increase in pressure. So there is some natural variation in the psig pressure (which is what your gauge really measures) all the time.

 

[RossKean]

Used to live in Fairbanks. Our garage was heated because we had a 300 gallon water tank in there. We had to keep it at 55 degrees or the furnace would not function. So imagine what it was like when we drove a car in or out in -45 degree weather. An instant 100 degree temperature change. We had to run nitrogen in the tires or the tire pressure system would go nuts.

For an ideal gas, a tire at 32 psi at 55 °F would end out at 25.8 psi at -45 °F. There is almost no difference in behavior between DRY nitrogen and DRY air. The biggest issue is that air from most compressors contains varying amounts of water vapor. At 55 °F, the water vapor may have a significant partial pressure (depends on degree of water saturation at that temperature and pressure) that contributes to the net pressure in the tire. At very low temperatures, the water will condense and freeze and will have VERY little contribution to the net pressure in the tire. Note: This is why you should use dry air when filling tires and also why you should be careful to minimize the amount of water-based tire snot getting into the tires when you mount them.

 

[Pterodactyl]

Yup. The tire pressure system functioned normally once nitrogen was used.

 

[wabill]

I had a valve core failure this week. No loss of air, but it was incredibly hard to pump air into the tire, rear. Core outer body had separated from the thread body. Just had a significant birthday and I thought old age had struck with a vengeance until I found I could still add air easily to the front tire with my hand pump.

 

[SouthBayDon]

Some interesting ideas, but I think I'm going to go with carrying a tire gauge. I've probably got a few lying around.

 

[wheatonFJR]

The air at gas stations...dry?

 

[ionbeam]

The air at gas stations...dry?

Yes. If -- the pump is tankless and it's January.

 

[RadioHowie]

The air at gas stations...dry?

VERY rare....

I spent a lot of times in my teens working as a pump-jockey. Besides cleaning windshields, checking oil, pumping 'tane and sweeping up, I was often tasked to "empty" the shop's compressor tanks. It was amazing how much water would build up inside those things in a week's time. If one waited more than 9-10 day, water would come spitting out the station's air hoses, it was so bad.

I imagine nowadays, in this day and age of self-serves, tanks probably never get emptied.

 

[Bogus]

Used to own a C-Store and would NOT use that air. We used a small pancake compressor since the brand we were affiliated with required us to supply free air to customers. Compressor was inside the store sucking up the more humid air inside. The hose ran out the wall outside, and many times in the winter, we would have freeze ups in the hose.

Side story: My pet peeve at the store was customers never hanging the hose back up when finished airing up. The end of the hose would be lying in the dirt, snow, and ice, and had to be replaced often. Finally made up a sign that said "AIR--$1.00 IF YOU HANG THE HOSE BACK UP WHEN FINISHED--FREE. You would not believe the difference it made on people hanging the hose back up, and the number of little old ladies coming in the store to pay the $1.00!!

 

[cota95]

I used a TPMS called Smarttire for years, which saved me once. They no longer sell a cycle system so I went with a Doran system. Around $200 if I'm remembering correctly and new sensors, which last a couple of years, can be had for $25. Can check pressure on the move at any time Wouldn't ride long distance without one.

 

[TomInPA]

The air at gas stations...dry?

VERY rare....

I spent a lot of times in my teens working as a pump-jockey. Besides cleaning windshields, checking oil, pumping 'tane and sweeping up, I was often tasked to "empty" the shop's compressor tanks. It was amazing how much water would build up inside those things in a week's time. If one waited more than 9-10 day, water would come spitting out the station's air hoses, it was so bad.

I imagine nowadays, in this day and age of self-serves, tanks probably never get emptied.

Hey old-timer! Today, (nowadays) you drop some coins into a little box, push a button, and a small compressor runs and might inflate your tire, before time runs out. Moisture control is not part of the equation, and neither is a tank. I too remember when service stations had tools, mechanics, lifts and service. LOL.

 

[HotRodZilla]

Any of you guys that don't run air dryers in your compressor's exit line are pushing humid air into your tires anyway. Stop being so anal and pretending that only special air will do in your tires. Fill the dammed things up and ride...

 

[RaYzerman19]

Used to live in Fairbanks. Our garage was heated because we had a 300 gallon water tank in there. We had to keep it at 55 degrees or the furnace would not function. So imagine what it was like when we drove a car in or out in -45 degree weather. An instant 100 degree temperature change. We had to run nitrogen in the tires or the tire pressure system would go nuts.

Even in places like Colorado. You get these cold fronts from Canada (Blame Canada...). 70F degrees at 11:00 AM, 0F by 6:00 PM and -20 the next morning.

But here's another factor nobody has mentioned: Make/model of tire. Let me 'splain:

My airplane (like most small planes) has tube type tires. The tires are Goodyear (wildly common). Tire pressures: 2.5 bar (36 psi) and 2.0 bar (29 psi) in the mains and nose wheel, respectively. The plane also came with Goodyear tubes. The compound Goodyear uses in their tubes is such that you had to add air every 2-3 weeks. I replaced these with Michelin tubes. Now it's months between needing to add air.

This is information that is not available to you when you buy tires for bikes. I don't know how one might find this out: What is the diffusion behavior of the tires you're buying?

To put some balance to all this: Your tires heat up while riding and the pressure therefore increases. AND for those who are traveling mountainous areas, there is a decrease/increase of roughly 1 psi for each 2,000 vertical feet one ascends/descends, respectively. Doesn't seem like a big deal unless you drove from Whidbey Island, WA to the top of the highway in Rocky Mountain National Park, like I did a couple of years ago. That's worth 7 psig increase in pressure. So there is some natural variation in the psig pressure (which is what your gauge really measures) all the time.

There is truth to this.... all my years in OEM automotive.... Goodyear said their tires lose 1 psi per month on a car. I suspect all manufacturers differ in their tire "porosity" but it is not unusual for one to lose a pound or two in a bike tire in a week or so. They don't hold nearly the air that car tires do and thus any small loss is seen as a larger PSI drop........ bottom line, check your tire pressures at least weekly. I use a TPMS (Doran) where you can easily check tire pressures without tools.