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Dum&*%@ flat tires

My new 2014 Toyota Avalon Hybrid has 17 inch wheels. I find that when the temperature dropped from hot to brisk, as fall arrived, the AM cold tire pressure dropped from 33 psi to 27 psi (yes, yes, all 4 tires, in the shade, before driven, blah blah blah). I attribute this to the silly pancake tires we are forced into buying. Thank the gods I didn’t have to get 18 inch.
This is a new problem, which I expected, but it’s worse than I expected. Add this on to the harsh ride and the increased probability of tire separation from rim. I CAN’T BELIEVE the public got itself suckered in by a few corporate schills into buying these things, and some people even try to get bigger wheels. No, wait, I can believe it. I feel like going out and spending some money to get 15 in wheels and all new tires. Anybody know if that is even possible? While I’m at it, could I get away with eliminating the tire pressure sensors?

You could eliminate the tire sensors, but why. The light would be on all the time.

Besides your problem is that you didn’t go and get your “air flush and cold weather air installed”.
That summer blend will set off those sensors off all the time. I have the “Arctic Blend” in mine because it has Musk Ox snot blended in to keep the sensors from freezing. But don’t get that stuff on your hands…it just doesn’t wash off.

Granted it’s a pain at times having them, but unless one is bad I wouldn’t eliminate it.


When attempting to change to smaller rims…especially on a hybrid…test fit before you buy anything for the clearence of the brake calipers.
My 06 Escape hybrid can NOT accomodate the 15" rims available for that year non-hybrid.

You can , if you wish , choose to not use the tpms sensors. You’ll either live with the light or maybe pull the fuse and just use the good ol’ tire guage once in a while.

I don’t see how low profile tires would cause extra pressure loss when it cools off. What size are they, exactly? 50 series?

edit - tire rack says they’re 215/55-17. These days, that’s a pretty normal size. Both mine have 50 series, I haven’t noticed any major pressure loss with colder weather.

They do sell 215/60-16 winter tire sets for your car, but it wouldn’t be worth it to me just to go from 55 to 60 aspect ratio.

I also don’t see how the aspect ratio of your tires is a factor here.

Unless your morning temperature dropped by 60 degrees, I’d say your tire gauge is inaccurate, you have leaks, or your memory of being at 33 PSI is incorrect.

I was having a hard time getting consistent tire pressure readings from my 2013 Equinox with 225/65R17 tires. Setting the cold tire pressure at night finally gave me consistent readings. Sunlight alone caused a 2 psi difference between the sunny and shady sides of the Equinox.

Ed B.

I get tired of people repeating things I already eliminated. OK OK:
Same tire gauge used both times.
2 tire gauges used as a double check.
I do not have Alzheimers.
No, there was no incident sunlight.
The most sensible thing said so far concerns the Musk Ox snot.
Well, and Ken Green’s post on the brakes. Any way to find that out short of trying it?

The tires (55 series) have less volume of air than the big ones. So, the pressure drop more normally reflects the Cv than the Cp (for those used to thermo). The walls have less “give” and so when it gets cold, the tire does not shrink as much. If it did shrink, as in bigger tires, this would help keep the pressure up.

I have never seen the low pressure warning icon, so I have no idea how annoying that would be.

This car really annoys me. Today when I wanted to drift it back to bring the valves to the top,
it wouldn’t let me do it with the door ajar. Hadda be latched shut.

You lose 1 psi for every 10 degree drop in temperature. So when it goes from 90 to 30, you lose 6 pounds, which is what happened to you. It happened to you on your old car’s wheels too, but you just didn’t notice because you didn’t check your tire pressures like you should have. The TPMS is now doing that for you. Why is this a problem again?

I should probably check my tire pressure more often than I do.

I don’t worry if it’s within 2# one way or the other as long as the tires have been sitting for an hour.
Time of day, weather it’s sunny out, if it’s an even day or an odd day, if I’m wearing boxers or briefs…I don’t take any of that into consideration.

If parked in the sun was that critical, I’d have to only drive down the shady side of the street.
I’ve visited the shady side of a few streets and it ain’t a pretty sight.


I’m just anticipating a problem on the tire sensors. When the batteries go dead and I have to have all 4 tires dismounted remounted and rebalanced. For a feature I don’t need, because I do have a tire gauge. That has nothing to do with the pressure problem except that it’s another feature designed for idiots that is going to cost me money.

Now back on the tiresome replies to the obvious posts.
The am cold temp went from 75 to 45.
The car had been sitting for 10 hours in the shade.
Both times.

Gas law: P = (nR) T/V
with the old type tires, when T dropped V did too so the pressure didn’t drop so much.
now, with the stiff little tire, V stays the same, so P drops more.
n and R are constants here.

Sidewalls affect ride, they don’t support the car in that range of pressures. Unless maybe if you have run flats - do you?

Why not just maintain a few extra PSI in your tires so you don’t get low in the cold?

Hop on the highway and drive 10 minutes. Theyll probably return back to the 33 psi. Who gives a sandwhich?

Your brake calipers will not accept 15" rims.

You should thank your deity of preference that this is the biggest problem you have. And, in truth, it isn’t a problem at all. just bring the tires up to pressure at the nearest service station and move on with life.

When the batteries go dead and I have to have all 4 tires dismounted remounted and rebalanced.

I get about 50,000 miles out of a set of tires, and I go through them long before the batteries in the sensors die. Just have the batteries changed when you need new tires.

For a feature I don't need, because I do have a tire gauge

Except that apparently you do, because your tires were sitting at 27 psi instead of being inflated to proper levels.

I get tired of people repeating things I already eliminated. OK OK:
The most sensible thing said so far concerns the Musk Ox snot.
Now back on the tiresome replies to the obvious posts.

Is there a reason you’re being a hostile little jerk, or is it just your standard operating procedure?

Some people just aren’t happy unless they’re miserable…
Anybody that can exaggerate such a nonproblem into such a rotten day MUST be one o those people.

Tire pressure drops about one pound every ten degrees. So you have 50 degree swings ? @jasmed1 just suggest a few extra pounds for those anticipated 50 degree drops…or buy a real HUMVEE and change the pressure as you drive. Why did you ever buy the car to begin with ? Should have just bought an old VW with really high profile tires. They rode so much better.

Unless the laws of physics have been repealed where the OP lives, the pressure in his tires would not have dropped by 6 lbs as a result of a 30 degree temperature drop, no matter what type of tires he has.

A drop of 3 lbs?
Six lbs?

Something is wrong, and based on his follow-up responses, I won’t even attempt to suggest what might be wrong.

No run flat tires.
They are now at 35, in order to compensate for further drops.
As those familiar with this car will know, the ride will now be rock hard.
At least it’s safer than too low pressure.

Sounds like Buyers Remorse and off his meds.