Watch your tire pressure monitor!

I traded in a Chevy Malibu to get my Prius. The Prius beats every electronic gizmo in the Chevy hands down, except for one. I could directly read the tire pressure in each tire right in the middle of the speed gauge. It was accurate too. I do miss that.

 

I've never had the TPMS warm me yet, but the manual implies it's meant to make a sound. See the last bullet point in this screenshot...

Pixel 2 ?

 

tpms is like the low oil warning, too little, too late.

 

Hmmm, I'm not so sure. Despite the warning not been noticed quicker, it sounds like it prevented tyre damage, and hence potentially a blow out or worse, in this example.

Pixel 2 ?

 

yes, but it doesn't come on until the tire is woefully under pressure, which could be a potential hazard.

 

If you connect the car to a Techstream, it can show the real time TPMS data. It shows the current pressure in each tyre, and the threshold that the warning will activate for each tyre.

When I had mine inflated to 36PSI, resetting the TPMS through the car's menu set the alarm trigger level to 30PSI. I don't know if it uses 6PSI below as the threshold, or something close to 15%.

When moving, the tyres will of course heat up. My previous car could display the tyre pressures while driving, and they used to heat up by 5PSI while traveling at 70MPH. So if the Prius is the same, I would expect a hot tyre to drop by around 11PSI before the warning fires. That gives you in the region of slightly above 20PSI (cold) remaining, which will definitely cause issues in the long term, and have a slight impact on safety, etc, but with a slow puncture that would give you plenty of time to stop safely, prevent a blow out or accident, and save the tyre.

You can also reduce the error margin by tricking the system into setting a higher trigger level. To do this, over inflate your tyres to, say, 5PSI over. Reset the TPMS. Then reduce the pressure by 5PSI. That way it will trigger at 1PSI down when cold, or maybe 6PSI under when hot. The downside of this is that you will have to reset the TPMS when the weather turns cold, as otherwise the TPMS will fire shortly after setting off.

Pixel 2 ?

 

I remember someone saying what they do is air up the tires to sidewall maximum, reset TPMS at that level, then reduce pressure to whatever they use. That way the warning light comes on after losing just a few pounds.

EDIT - similar to what The Professor just said, just a different method that works for them at their tire pressure setting.

 

iirc, there is at least one other car besides Tesla that lets you switch from one dash display to another. So one of those displays is the 4 individual tire pressures shown in their corresponding location. We keep that screen on the left side as a constant;


... while the other side we use as display for consumption. The service center always drops the tire pressures, necessitating me to Jack them up a ½-dozen lbs as soon as I get home - which makes the tread last a whole lot longer. That reminds me - our front right tire is a couple Lbs low. I hope all manufacturers follow suit to allow that kind of constant display as well as display choices.
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On the RX450h when you switch driving modes, the display changes.

Eco mode is blue, normal mode is gray and power mode is red and the hybrid system indicator switches to rpm’s. The f sport version has even more that changes, but one option in the center of the display is tire pressure monitoring and the 12.3 inch screen on the dash has many options to choose from.

 

If you're near a compressor, let some air out of the tire(s) & test it to see if it works.
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You might want to consider getting a set of these to help keep an eye on things Michelle. There are alternative models, so it's really your choice.

Edit: in case that didn't show right, they're on that big River website,
Vesafe Tire Pressure Monitoring System TPMS with 4 DIY External Cap Sensors (0-6Bar/0-87Psi), Wireless Real-time Cigarette Lighter Plug TPMS CL-203 with USB Charging Plug (Current: 2A)

 

Rather than to go this route, I decided to get a tire pressure gauge and inflator I can hook up to my pressure tank. I check my pressure every couple of weeks and I keep all of my tires pressurized to 1/10 of a PSI. I put an extra pound in each tire compared to what's recommended in the door sticker. I'm getting great milage and the tires seem to be wearing evenly. It's a bit more work but I'm sure that it is worth it. I tend to replace all of my tires when I purchase them.

 

There are economies of scale of you by for at a time in UK . I assume it's the same over there.