biacs

Ive had the car for about 6 years. I just wanted to ask or at least point this out. I live in central Illinois so we get the nasty rainy ice slushy -45 windchills, lucky us. Every year I'll get Low Tire light. I check the tires and they are all fine, so I reach under and clear the light and wait for a re-trigger.

Is this just a low battery in a sensor that the cold can trigger?

Nothing better than a blizzard and DING the Low Tire comes on, but at least the pressure was fine!

Johnhav430

I'm not convinced the system even works at least on my car. I had a flat and no trigger. I know there are no sensors in the rims, so it must work by wheel rotation. But if the indicator did turn on, I'd walk around with a gauge to check. I don't see why cold weather would trigger low tire warnings other than the pressure was already marginal and the low temps took the psi below a threshold. We're talking 1 psi for every 10 F, so conceivably 35 F to -30 F could be 6 or 7 psi.

Gronemus

My light came on during the first cold wave late last week. When I checked the pressure all of the tires were at 30 psi. Everything's shrinking in the extreme cold so I'm not going to worry about it much for now and just reset it in a couple of days when it gets warmer.

BTW, tires don't care about the wind chill. They will only get as cold as what the actual temperature reading is...

iingham

TPMS in the LS doesn't use sensors in the wheels, it compares the rate of rotation for each tire and if one is off by some amount, triggers the light. I think it uses the ABS speed sensors? Not sure.

I know it works because when I got my car, the dealer installed new tires (yay!) but didn't change the 12 year old valve stems (boo!) and one leaked the air slowly out of the tire, eventually setting off the TPMS light.

Plus they installed crappy cheap tires.

bradland

I got a drywall screw in a tire this past summer and no warning light whatsoever. It was in the front so I felt it in the steering immediately and quickly turned around only drove a few blocks...

ls430w140

As far as I know, the tire monitoring system has the be reset each time new wheels are installed or new tire pressure level is set in order for it to work effectively. Low Tire Warning light may not only detect excessively low pressure, but also internal structural tire damage affecting rotation.

Johnhav430

Ditto, I can't explain it but I had an all out flat, no indication.

Other than costing more, esp. when you use snow tires, let's face it, having an actual sensor works, instantly upon startup. But some of course is common sense too...

ls430w140

Johnhav430

Haven't got the software...but one would think my ABS would not be working if the tire pressure system were not....not sure though. I know 2 of our other cars have actual sensors, and they don't seem to trigger even at 5 lbs. difference. But on one car verified with a flat the car indicated which tire via a diagram on the dash (that is new and totally software, originally was just a warning).

Daspyda

iTrader: (1)

I get that...and I am in FL.

BigBoomer

Mine tells me that I have a Low Tire but not which one (2004 facelift).
Indirect TPMS works on differences in wheel speed.
Plenty of info here Indirect TPMS
If you are getting Low Tire messages but the pressures are good, try doing the Reset procedure and then go for a good drive (at least 30 mins) to give it some data to use.

LS430inDE.

Unless your tires were installed then inflated with nitrogen, they will ALWAYS have lower PSI in cold weather as compared to warm weather. According to this article, car tires will lose about 1 PSI for every 10deg F drop in air temperature.
Check out this article here....---- > Informative linky for air pressure during cold weather

It's like clockwork around here (mid-Atlantic area) when the temperature starts dipping below 40deg F, you can see car after car lined up at the (scarce) free air pumps, usually at the convenience stores called Wawa. I know John loves him some Wawa when he shops at our tax free Walmarts, LMAO!

When you describe the false positive during the cold weather and you say you check your tires, you're placing a gauge on them and they read about 32PSI or more?

You also need to remember that you need to have about 32PSI COLD. That doesn't mean when the weather is cold. That means that the CAR hasn't been driven for more than about 5-10 minutes. Your tire pressures will INCREASE when driving, even in cold weather. It can vary as much as 10%. Perhaps in your case, your cold pressure when you leave your driveway, is in the 20's then when you've driven it enough and pull over to measure at an air pump, they increased showing 29 or 30 or even 32PSI? etc?

To beat the horse, there aren't sensors nor batteries nor electronics on each tire/rim. The system uses wheel rotations and a computerized calculation. I would imagine if your TPMS has never been initialized PROPERLY aka by the book, you could have unreliable TPMS indications also.

Vantage007

I get false positives all the time in the winter. The car is fine in warmer months, but with the winter tire set mounted and temperatures below freezing, I consistently get the "Low Tire" warning despite all four tires sitting at 32-35psi. I use the reset button and it usually comes back within an hour or so of driving. I honestly wish there was a simple way to defeat the TPMS in this car.

ls430w140

Vantage007

This is the first winter this car has seen, and I put brand new General Altimax Arctic 12 on it. The tire light consistently comes on when temperatures dip below -5 to -7C or below, and it's fine in above-freezing temperatures. I've checked the tires numerous times with multiple tire gauges, and they're always consistent. Before I learned that our cars don't have physical TPMS sensors, I thought one might be failing. There's no sensor system for the spare in the trunk, is there? Just realized that's the only one I haven't checked the pressure of yet...