Cold weather takes air out of your tires

[pheeh.zero]

You are wasting your time if you use a $2 gauge though!

[pheeh.zero]

Rust, by definition, is iron oxide and not aluminum oxide. (PHD or not)

I would except aluminum "rust"!

[Andrew]

The law in question here is called Boyles Gas Law. It states that:

PV=nRT

where: P = pressure of the gas V = Volume of the container n = number of molecules of the gas R = the universal gas constant T = temperature

So, if temperature decreases, and all else stays the same, pressure goes down proportionally.

[Frank]

I always get Boyles and Charles mixed up but what you state is the ideal gas law which is easier to remember:

Any high school graduate should a rough idea of temperature/volume/pressure relationship of gasses. It is also good to know that temperature is in degrees Kelvin and difference between pressure in a hot and cold tire is only a few pounds.

[tnom]

Bull. What remains is thin coat of soap that helps seal the rim.

[Rick Brandt]

How exactly would you determine that? One would need extensive controlled testing comparing similar wheel/tire combinations some mounted with tire paste and some without and then periodic measuring of leakage rates. Have you done this? Has anyone?

I expect that if using paste has any anti-leak properties it is largely because the bead is not abraded during mounting, thus having a better surface mating to the rim. The act of application might also be removing some surface dirt which is also going to help the seal.

Since virtually 100% of tires that are professionally mounted will be mounted using paste and since we have people reporting bead leakage then the evidence seems to indicate that the sealant properties are pretty poor if not totally non-existent.

Now, is it possible that amongst all of the varieties of tire paste on the market that a few make claims about assisting the seal? I have no problem believing that, but that would be a special formulation that deviates from what the primary usage is for the product.

[dpb]

Rick Brandt wrote: ...

I'd certainly have expected the manufacturers, SAE, etc., to have done quite a bit in the area, yes...

The following is conjecture as opposed to actual research since I can't inspect the rims of those who have complained... :)

But, w/ the number of vehicles I both have now and have had over some

40+ years, I've only had one instance I can think of where leakage around the bead was a real problem and that is on a tractor I currently own. It is owing to a damaged rim which I finally just replaced last month after being tired of fooling w/ it any longer.

I really think most problems are due to either rims being damaged (curbs, rocks, etc., can ding up rims as well as an overly ambitious tire shop jockey) and the problems of ensuring the rim bead area is indeed clean and free of debris is an issue. Plus, there is a tendency besides the mechanical damage noted above for steel rims to rust and pit and alloy rims have their problems as well. But, w/ all that, ime it simply has never been an issue I've seen as being frequent at all. But, of course, if one counts the total number of tires, a pretty low failure rate can still add up to quite a number of instances. And, it only takes one for any individual to get the impression it's a problem. :)

I wondered that as well and did find a couple of manufacturers who did note it helped seal bead as well as lubricate. The fairly common "purple glop" was one that did mention it. It isn't, however a special formulation for the particular product, but a claimed extra advantage. The same company (as do many others) does have a separate product which is designed specifically to be a bead sealer as well as lubricant for the problem cases.

It appears the most widespread lubricants are potassium coconut soaps with ionic surfactants (wetting agents); the purple product and its ilk claim no soaps but are very ambiguous about actual ingredients...

--

[hallerb]

the yellow goop NTB used remained semi pliable I peeled some off but under it was white powder corrosion of the alunimum

[Steve Barker TB]

nope, it's not soap and it doesn't remain.

s

[clare]

Ruglyde IS a soap, and some DOES remain. However, the pressure loss in cold weather is generally temporary and the pressure comes back when the temperature goes back up UNLESS the hard tire is stressed so that it unseals from the rim - the "Ruglyde" is not a sealer.

Ruglyde is made by "American Grease Stick" (AKA AGS ) and the MSDS says it is a mixture of potassium vegetable oil soap and ethylene glycol

AGS Company RuGlyde MATERIAL SAFETY DATA SHEET SECTION 1 - CHEMICAL PRODUCT AND COMPANY IDENTIFICATION Product: RG-18, RG-18BK, RG-18CT, RG-18MY Trade Name: RuGlyde Rubber Lubricant RG-20, RG-20BK, RG-20MY, RG-55, RG-55BK RGC-18, RGC-20 Manufacturer: AGS Company Common Name: Tire Mounting Lubricant Street Address: 2651 Hoyt St City/State/Zip Muskegon Hts., MI 49444 Phone: [phone] Phone: [phone] FAX: [phone] Original Issue Date: 11/8/1985 Transportation Emergency: CHEM-TEL Revision No. 9 Date 1/31/2007 Phone: [phone] SECTION 2 - COMPOSITION/ INFORMATION ON INGREDIENTS ITEM CAS NUMBER WT/WT %

1 Potassium Vegetable Oil Soap N.E. 7-13 2 Ethylene Glycol 107-21-1 1-5 ACGIH OSHA ITEM TLV-TWA TLV-STEL PEL-TWA PEL-CEILING 1 N.E. N.E. N.E. N.E. 2 N.E. 100 mg/m3* 50 ppm N.E. (See Section 16 for abbreviation legend) * Ceiling Limit SECTION 3 - HAZARDS IDENTIFICATION

[clare]

Rubber hardens with age, aluminum alloy corrodes from roas salt, and steel rims rust.

All contribute to rim leakage - which is a common problem in the "rust belt" where NaCl is heavuily used as a road de-icer in the winter. However, this is NOTa strictly cold weather pressure loss phenominon.

Cold weather pressure loss is adiabatic? - having to do with expansion and contraction of a gas with temoerature. PERMANENT cold weather pressure loss is due to hardening of the bead rubber in cold conditions and is GENERALLY worse if the tire pressure is already low, allowing the sidewall flex to force the bead to move against the rim. Being hard from the cold it does not readily re-conform to the rim, particularly rims roughened by corrosion.

The yellow "goop" used as a tire sealer by many tire shops is nothing more or less than trim adhesive and is virtually useless, particularly on corroded alloy rims. Best solution there is a good wire brushing, a quick application of an etchant like phosphoric acid (metalPrep) and a good coat of an appropriate primer/paint. This keeps the "white powder" from growing in the bead area, releasing the air from the tire.

[Dan]

on 1/31/09 7:25 AM Ed Pawlowski said the following:

try to check tire pressure at room temperature. if you check at 0 F and fill to pressure on the label by door frame, the air will be more dense and then when the tires heat up from driving the tires may be "over-inflated". But make sure to use the label on the door frame (not the label on the tire).

[Steve Barker TB]

OK, that's one brand. What if it's not ruglyde that we're talking about?

s

[tnom]

It is soap. Where are you getting the idea that it isn't?

[Stormin Mormon]

I've heard that the chemicals needed for making electric car batteries are worse than what's used for a normal car. The expen$e and chemicals used for electric cars are far worse than the usual cars. No, I don't remember where I heard this.

[clare]

The VAST majority of tire mounting fluids are the same, and in my experience most tire shops were using Ruglyde.

[TimR]

Do you think the weight of the car has anything to do with the inflation pressure?

Many years ago I watched a mechanic check the pressure on my tires while the car was up on a lift, the wheels hanging loose.

I asked him if he was sure the pressure would be correct once the car was on the ground and the weight of the car was on them. There was a reason for this - I was a high school kid, working a summer job. I'd loaded a trailer too full at work and blown a tire, and got my butt chewed good by the foreman.

The mechanic when he got done laughing called me a moron and told me of course the pressure would be the same in the air or on the ground. Okay, but I wanted him to recheck once the car was down. He got the same reading and laughed some more at this dumb high school kid. Still not sure he was right, though.

[Phisherman]

Well, the tire will have a higher PSI on the ground than when the vehicle is suspended in the air, but not much. A regular tire pressure gauge may not be sensitive enough to show the pressure differences.