Tire pressure and cold temperatures. How do they warm up while driving?

[Packard]

The last 10 days or so it has dropped below zero every night. Apparently, it dropped to -18 last night according to the weather guy on TV. It was minus 10 degrees (actual, not wind-chill) when I woke this morning. One of my tires dropped to 24 PSI, and the warning light came on. The other tires were all at 27 PSI.

I keep a Milwaukee portable tire pump (battery powered) in my car, so I did not have to run to the gas station. In a couple of minutes I was back up to the prescribed 30 PSI.

Question: I drove 4 miles to the local Starbucks. By the time I got there all the tires had warmed up enough to increase the tire pressure to 29 PSI. My guess is a couple more miles and they would have made it back to 30 PSI.

What is the mechanism that warms up the tires while driving? I imagine it is just the flexing of the tire walls while driving, but how would that work?

As an aside, I have a glue-up to do. My basement shop has gotten colder daily from the cold weather. What is the lowest temperature at which I can glue up using Woodworkers 3?

 

[tjbnwi]

Friction.

Back in my circle/oval track days we would adjust the air pressure on the left and right (at times front to rear depending on the track) tires to make up for the two different distances the tires had to travel going around the track. Then came nitrogen…..(not really needed on a street vechicle).

47º

Tom

 

[Packard]

Friction.

Back in my circle/oval track days we would adjust the air pressure on the left and right (at times front to rear depending on the track) tires to make up for the two different distances the tires had to travel going around the track. Then came nitrogen…..(not really needed on a street vechicle).

47º

Tom

Friction between the rubber and the asphalt?

And 47 degrees minimum. My basement is down to 62 as of last night. So I am good to go. Thanks.

 

[tjbnwi]

Friction between the rubber and the asphalt?

And 47 degrees minimum. My basement is down to 62 as of last night. So I am good to go. Thanks.

Yes, [primarily] the friction between the rubber and the asphalt causes the moisture that is in the air contained in the tire to expand.

Tom

 

[Packard]

Yes, [primarily] the friction between the rubber and the asphalt causes the moisture that is in the air contained in the tire to expand.

Tom

I was surprised how quickly the pressure changed when driving. But it is a small, enclosed chamber with nowhere for the heat to quickly vent—so thinking it through, it all makes sense.

Having lived through the era of the Ford Explorer/Firestone Tire recalls (like, 250 people were killed) and the issue of low tire pressure, I have remained hyper aware of my tire pressures. The tire pressure alert systems in my cars have only added to that.

The Milwaukee tire pump is A-1, and not too expensive if you already have the charger and batteries. I have the M12 compressor. There is now a M18, but for adding air to a tire, the M12 is sufficient. Handy and light. Nice now especially since gas stations are charging money to get air.

 

[Vtshopdog]

Ideal gas law:
Pv = nRT

P is pressure
V is volume
T is temperature
n and R are number of gas molecules and the gas (expansion) constant.
Filling a tire with Nitrogen reduces pressure fluctuations from temperature changes as Nitrogen has a lower gas constant

Ideal gas law - Wikipedia

en.wikipedia.org

 

[Vtshopdog]

FWW
I had an OEM Firestone front tire on my 94 Ford Ranger blow on the interstate going about 75 MPH. Fortunately I was on a dead straight section of I-90 near SD badlands with no other vehicles nearby and merely had to keep things aligned while coasting on a slight uphill. Had it been the outside tire on a corner, well, maybe I wouldn't be typing this right now.....