TYRE PRESSURE

[007Cruiser]

Re: TYRE PRESSURE

Glad this is finally settled.

[Daktari]

Re: TYRE PRESSURE

Hi there,

Thanks for the in-depth technical info Jay. I will certainly be checking my pressures on a fairly regular basis just like I did with all air in the tires.

However, after all the technical jargon, surely the proof is in the pudding as they say. If, having all nitrogen in the tires does in fact keep the pressure more constant, then surely it is worth doing, especially if it is a free service.

Just my humble yet common sense opinion.

Gordon.

[Bill Brown]

Re: TYRE PRESSURE

Jay are you staying at a Holiday Inn Express? Excellent answer to all the confusion.

[rmarshal]

Re: TYRE PRESSURE

A mixture of 78% nitrogen with addition of various exotic gases (such as oxygen) works best.

[HKS]

Re: TYRE PRESSURE

Jay,

Great explanation and reasoning. Fun to read.

HKS

Let’s put some science (and logic?) to this …
1. Air is 78% nitrogen & 21% oxygen (1% other gases) … you already have mostly nitrogen in your tire if you use air for inflation..
2. Upon installation when the tire is seated on the wheel, the volume in the tire is 100% air at atmospheric pressure. Most installers won’t draw a vacuum and evacuate the existing air, nor will they fill & bleed the tire multiple times to purge the existing air.
3. Tires are inflated to a little more than twice atmospheric pressure which is 14.7 psi @ sea-level and 12.2 psi @ 5000 ft. … so you put 2 – 2.5 times the amount of gas into the tire.
4. Taking #2 & #3 into consideration with pure nitrogen added, you’ve only reduced the existing oxygen in the tire to 8-10% (from 21%).
5. (OK, this gets a little more technical) At the pressures we’re talking about, both gases are acting in an ideal gas state. This means the Ideal Gas Law applies to both: pV=nRT Also, assuming the volume is constant in a properly inflated tire, Gay-Lussac’s Law says that pressure is proportional to absolute temperature for all ideal gases (both nitrogen and air). Both will vary the same with temperature. Now some will say that truck tires and aircraft tires have proven otherwise; however, these tires are at much higher pressures than ours (less like an ideal gas state).
6. What we haven’t discussed, but is really the bigger issue, is the water vapor present in most compressed air stations. This water vapor is also the concern at very high altitudes (aircraft tires). For us, if you’re in a high humidity environment, the pressure variation with temperature is slightly greater in (wet?) air compared to (dry) nitrogen. But again, consider #2 above … you’ve still got almost half-“air” in your tire.
Bottom line? If it’s free, go for it ... you might gain some very small theoretical improvements. BUT, you will lose just as much pressure with time as you do with air since small bead and valve leaks cause much greater loss than through the rubber molecules (which nitrogen promoters advertise). So don’t think you’re tire is fine because it has nitrogen. And if you have limited locations/opportunities for nitrogen refill (due to small bead or valve leaks which leak both gases) you may be more likely to drive longer on under-inflated tires.
Best recommendation? Check your tire pressure frequently regardless of what gas you use in your tires.

[AZTB]

Re: TYRE PRESSURE

32 lbs cold and use helium...makes for a lighter ride!

[rmarshal]

Re: TYRE PRESSURE

Use krypton--it's inert (noble gas) and keeps Superman from ripping off your 'Bird.

[Peterfurlan]

Re: TYRE PRESSURE

Thank You Jay just another scam. How would you purge the air from a tire before
filling with nitrogen. Two valve stems?

[FEsTbird]

Re: TYRE PRESSURE

Regardless of whether it is nitrogen or air, I use about 10% more pressure when on a trip than driving around town. Usually 30psi around town and 32-33psi on the highway. This is the Michelin recommendation and I have found about 10% better mileage on trips. Using 30psi softens the bumps and potholes that we are getting increasingly as California slips toward being a "third-world" state.

[mwhit]

Re: TYRE PRESSURE

When I need to rotate the tires on my cars, I reduce the air pressure to 5 pounds before removing from the wheel studs. This reduction allows me to move the tire and wheel to the new location easier because it is 30 pounds lighter. After I have it reinstalled in the new location on the car, I air it back up to 35 pounds. Never pulled any muscles doing in this fashion.

[Daktari]

Re: TYRE PRESSURE

That's when the helium option might have been good, ha,ha...

[007Cruiser]

Re: TYRE PRESSURE

For all those using nitrogen, remember that now is the time to replace your winter nitrogen with summer nitrogen.

[DaiUyTed]

Re: TYRE PRESSURE

When I need to rotate the tires on my cars, I reduce the air pressure to 5 pounds before removing from the wheel studs. This reduction allows me to move the tire and wheel to the new location easier because it is 30 pounds lighter. After I have it reinstalled in the new location on the car, I air it back up to 35 pounds. Never pulled any muscles doing in this fashion.

I'm gonna run this one past my Middle School remedial science class...

[Ediron]

Re: TYRE PRESSURE

Gene I remember that signature about the doughtnut from the Mayfair Doughtnut shop in New Rochelle N.Y. cir. 1960's .They had a picture of two guys looking at doughtnuts trying to figure them.

[My T]

Re: TYRE PRESSURE

Hey Ted - -

Welcome. Please send me your e-mail address, so that I can put you on the list to receive information about our Central Florida T Bird event coming up in the Fall.

Tom Aglio - - - tjaglio@earthlink.net