TYRE PRESSURE

[JAB02LHS]

To what PSI do you inflate your tires?
AND
Do you nitrogen or air?

[tbird6t4]

Re: TYRE PRESSURE

To what PSI do you inflate your tires?

35 pounds all around. I do mostly highway driving with my Retro and it helps improve gas milage IMHO.

[V8 Cat]

Re: TYRE PRESSURE

32 Lbs (air) cold (at about 55 to 70 degrees in the garage).

[Ediron]

Re: TYRE PRESSURE

Cold 32 my new tires have nitrogen in them .Ford dealer used it no extra charge to me or plain old air would have been fine.I'll have to see if they hold the pressure better and longer.

[MEK04]

Re: TYRE PRESSURE

35 lbs and use air. Had nitrogen in the daily driver but got tired of waiting around for top ups at the dealer. On one occasion I picked up a nail (in the tire) the repair shop didn't want to plug it because they didn't have nitrogen and might affect the ride???????

[Chuck]

Re: TYRE PRESSURE

What's on the door sill? Never paid much attention to it, whatever Ford recommends that’s on the sticker? Oh and I use air, I have my own compressor

[Bird03]

Re: TYRE PRESSURE

My Ford dealer now sells Nitrogen.

[Lonestar]

Re: TYRE PRESSURE

When the suspension designers design the comfort aspect of a vehicle, and naturally the comfort factor for a Town Car is different than a Thunderbird, they have four primary factors to play with: springs, shocks, the seats, and tire pressure. Typically manufactures of radial tires ideally want the tires @ around 35PSI. This pressure in most size tires results in enough pressure to provide a flat foot print and provide adequate stiffness to the side walls to keep them from breaking down. To compensate for the limited travel of the shocks and springs in the Thunderbird, couple with and attempt to make the handling crisp, I suspect the suspension designers opted for 30 PSI tire pressure so as to allow the tires to absorb road shock and compensate for what otherwise might not have been a semi-soft ride.

Some Thunderbird owners have opted for 45, 40, and I think we had one member that went to a 30 series profile tire. For these tires the pressure has to be well beyond 30 PSI and the tire manufactures may recommend as much a 50 PSI. This is to keep the sidewall stiff enough to absorb what is encountered typically on any road USA and to avoid a wheel from coming into contact with the pavement or a tire bead from being damaged during an aggressive turn or hitting a pot hole. Naturally the trade off is a less comfy ride.

You always have to play with pick-up and SUV manufactures recommended tire pressures because they assume a fully loaded vehicle.

For those moving to bigger rims and lower profile tires… you will need to check the tire pressures more often for you will probably find that they swing far more then the OEM size will. The lower profile tires will build pressures quickly at speed and then drop usually below where you had them set with virtually no swings in outside temps.

[THX1138]

Re: TYRE PRESSURE

Thanks Lonestar. Great information.

[Leroy]

Re: TYRE PRESSURE

Nitrogen is an inert gas that doesn't expand or contract with temperature changes. It's used in millitary aircraft tires because of rapid changes in temperatures at different altitudes. The slight temperture changes we have driving our cars has little effect and in my opinion the use of nitrogen is a waste of money. Leroy

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[Daktari]

Re: TYRE PRESSURE

Hi there,

Honestly, I would not have thought of using nitrogen in the new tires but they said it was free because I had vouchers handed to me the last time I was in there.

"Ok", I said, "I'll try it, but does it have any effect on the pressure of the tire"?

They told me it was more stable and the tire pressure would be more constant and not vary so much between hot and cold temps. I don't know now if they meant the tire temp or the air temp. Hey, if it's free I thought I'd give it a go and they fitted nice green tipped caps also. Plus they said if I needed more just to bring it back and they would top it up. Ok as long as they don't take it up to the 47 psi that it was initially. ( 7 over the tire's recommended max pressure)!

Gordon.

[Lonestar]

Re: TYRE PRESSURE

Nitrogen is an inert gas that doesn't expand or contract with temperature changes. It's used in millitary aircraft tires because of rapid changes in temperatures at different altitudes. The slight temperture changes we have driving our cars has little effect and in my opinion the use of nitrogen is a waste of money. Leroy

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It (Nitrogen) is also used in commercial aircraft. Lots of debate here and elsewhere about. 6 or one a half dozen of another. The fact is that if your tire is aired to 30 PSI with air and the temp is 75 degrees and then the temp drops tonight to 40 degrees then your tires will no longer be at 30 PSI - they will probably be @ 27 to 28 PSI. With nitrogen they will probably remain at 30 PSI. Like wise if your tires are @ 30 PSI and you hit the interstate on a 90 degree day your PSI will increase to as much as 35 to 36 PSI, maybe higher if under load. With Nitrogen they may only reach 31 to 32 PSI.

Where I live it is a constant activity to keep the tires on my cars inflated correctly during the fall, winter, and spring months because of the temp swings. If it were free I would sure give nitrogen a go to see if this activity could be reduced.

[Ediron]

Re: TYRE PRESSURE

Temp. in S.fl. is one of the reasons I didn't mind the dealer using nitro in the tires.I'll see if they stay at a constant pressure.Before I was checking every week and getting various readings when cold.Like Gordon it was free.

[acar]

Re: TYRE PRESSURE

I was curious to read this thread as I just came out of the barn airing the tires up on the bird btw the spare was at 20# not 60# more than likely never check since new. Thanks to Dot I believe for that tip. All the tires were at 35# but the tires all say 44#. Tire Men have always told me never drop them over 10% because it will raise the tire temperture. And the lower the profile the more importain this is. So I put them at 40#. I know on my semi truck it has lowpros on the tractor and the trailer with the trailer being lower than the truck. The truck calls for 110# with trailer 120# They told me the same thing with less sidewall more pressure less flex less heat so I pretty much go on their advice. My compact farm tractor has the biggest tires of everything I got and they go 20# so go figure

[jayred1]

Re: TYRE PRESSURE

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 your 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.