Replies to post #3760 on Cars, etc. (GEARHEAD)

[Phil(Hot Rod Chevy)]

PW,

This is one of those times he is kidding you.

Good one though. LOL

Put some water in an old Windex (spray) bottle and add a little dishwashing detergent in it.

Take the cap off the valve stem and spray the Schrader valve.

Wait a little while and check it for bubbles.

If it's leaking, unless you have a special tool you will need to take it to a service station or tire store to have it tightened.

If it's not leaking, spray the whole tire with the soap solution and look for leaks. I doubt you will find any bubbles with that slow a leak if it's in the tire.

I wouldn't be too worried about a pound per month.

Declining temperatures could cause that.

To compensate, overinflate it by a few pounds when you add air and it should be OK for several months.

http://en.wikipedia.org/wiki/Schrader_valve

LOL

Phil

[OldAIMGuy]

PW, Save a step and just "bag" the compressor. Then you won't have to hook up a hose......................

Actually, many racers buy nitrogen to fill their tires on their cars. #1 it's dry, #2 it contains no oxygen.

Before spending money on a cylinder of nitrogen (unnecessary for daily driving), I'd want to know why the tire is leaking down. Could be rim or valve leakage. Unlikely but possible is sidwall or tread leakage.

The first car I had with aluminum wheels developed rim leaks where the buttheads at the factory had mounted the balance weights along the rim. After a few seasons in wintery salt brine, the aluminum wheels plus the steel weight clips and the lead of the actual weight formed a nice little "battery" and the corrosion worked its way in between the tire bead and the wheel. This caused a very slow leak. Eventually, when I bought new tires for the car I cleaned the rims and the sealing surface of the wheel and sprayed the area with clear plastic spray.

After the new tires were mounted (with new stems) I had no more leakage. We used "stick-on" weights from thereon and had no further corrosion problems.

So, if you have alloy wheels, take a look at where the wheel balance weights are mounted.

Best regards, Tom

[Bob Zumbrunnen]

LOL!

Initially I couldn't tell if you were pulling our collective leg or he was pulling yours.

It's the latter.

A pound of pressure per month is quite normal. As you said, oxygen molecules are quite small and can escape a seemingly non-porous tyre.

A lot of track folks use nitrogen to fill their tires. Doesn't leak through the molecule-sized pores as easily and has stronger thermal momentum. Hot tires stay hot longer and don't go through the hot/cold cycles as rapidly and frequently as air-filled tires.

Temperature variations (both ambient and tire temperatures) have a major impact on air pressure, as well. Depending on how aggressively you drive and how much air pressure was in the tires when cold, the difference between hot and cold pressures can be several PSI. The softer the tires when cold, the greater the increase in pressure when hot, due to the heat generated by the softer tire flexing more.

It's for this reason that it's under-inflated tires that blow out; not over-inflated ones. The huge increase in pressure from all the flexing combined with the weakening of the tire from the excess heat.