I Got Screwed

I know the difference between a screw and a bolt. I've never been bolted.

 

This seems like a classic physics experiment.

PV=nRT

Temp goes down - maybe pressure follows???

Of course, tracking the volume as the tire expands, may be a bit more difficult....

 

I've read that each 10 degF change in air temps results in ~1 psi change
in tire pressure...

I wonder how fast the pressure in the tire reacts to temp changes...
mere minutes or over a few hours?

Then there are pressure changes from temps due side wall flex and
tread squirm, about which I know nothing.

Funny though, today I got "nailed." Within 50 ft of my driveway TPMS
light went on. Nail in sidewall, ~1/2" above tread. Air leaking out so
fast you could hear it. Damn. Immediate fix required. Pump it up,
back into driveway, mount spare.

New tire... ouch!

 

Get a NITROGEN fill. This should remedy the problem with TP + -

 

Does NITROGEN have a legal exemption from the gas laws?

 

Jim, you don't happen to have Toyo's on your V, do you? I've had two bad tires in 6,000 miles.

Normally, tires don't lose much air, but occasionally, when the temp drops to about 30 degrees F, a tire can lose 20 lbs. in a few hours. Or it could be fine for two weeks. I haven't figured it out yet. I think there's a bad combination with the aluminum 17" wheels and the tires Toyota chose to use.

 

humm, 'Discount Tire' fixes flats for free in my area....and you can stand there and WATCH them work on your tire.

 

Correct.

For ideal gasses in the vicinity of ambient T and typical tire pressures it's very close to 1 psi for every 10 degrees F.

 

As to the speed of ambient temps affecting tire pressure,
a simple demonstration:

(My middle school STEM students who have done this
demo/experiment recently find it to be a constant source
of wonderment...)

Place empty 2/3 liter soda/cola/"coke" bottle in freezer.
Wait ~3 minutes.
Remove bottle from freezer.
Voila! PV=nRT comes alive!
The cooling takes but minutes.
Observe bottle as it returns to ambient temp.

I suspect that for tires there is some delay due the mass of
the tires themselves also needing to cool to ambient.

 

I had a similar situation on a different car, and it wound up being the rim. Is it the same wheel in your case when it does this? In my case, it was the 3rd set of tires on the car, and rust had built up on the rims (probably due to my lack of using nitrogen). I do not know why, but it was a 'come and go' sort of thing, and it happened in winter. Buffed the rust off, no more problems. In your case, with such a new car, I doubt it would be rust, but it might be worth looking into seeing if the rim is out of round. Have you hit a pothole hard or anything? (If it's more than one wheel, forget everything I said...).

Good luck
~T

 

... and what would Mr. Boyle have to say?
:amen:

 

Same tire/wheel every time. Not hit anything hard and its had random losses since nearly new.

 

The issue might be a not fully tightened nut on the TPMS valve stem.

 

"I got screwed" - ha - YOU got screwed? I got screwed more than you!

Stopped at a rail crossing, people in the next lane pointed out nearly-flat rear tyre (obUStranslation: tire).

Pulled over, called wife to come down and rescue the kids (of course it was 10 minutes into a 50 mile trip, and they were performing in a play and time was of the essence) while I rescued the car.

Small screw in the tyre.

Pull out the inflation kit (this is an iTech, doesn't come with a space saver spare in Australia) and figure out the instructions.

Inflate the tyre full of goop, run it home.

Call around the tyre shops the next day, gooped tyres can't be repaired, nobody has any Bridgestone Ecopia B250 in the right size. Bingo! One Bridgestone shop has one, but its the V-rated not H-rated. Fine, I'll take it. $240. Ouch.

Call Toyota to get a replacement bottle of goop. "How much?" "It comes as a kit, the sealant plus the opening key and a hose." "Yes, I know that, how much?" "$165."

"OK, how much for a space-saver spare?" "We don't sell them as a spare, only the rim and tyre separately." "OK, how much?" "$225 for the rim, $195 for the tyre."

So! $405 every time I pick up a nail or screw. Or $420 for the bright yellow option with a rubber band stretched around the outside.

You tell me who just got screwed.