Why does my tire pressure read low

The ambient 31F has caused the air pressure to drop below the low alarm point. This happens to me every winter. I just bump up the pressure to 36 psi so when the air in the tires is cold the tire pressures are all still above the alarm point. Alternatively you could replace the air in your tires with nitrogen. Nitrogen isn’t affected by colder temps so tire pressures stay more steady.

 

I've noticed the gauge for tire pressure on my dash always reads 1 lb. higher than my digital gauge....so the truck's gauge is pretty accurate.

 

Like all gasses, Nitrogen will be affected by colder temperatures: Depending on the initial pressure, a tire filled with nitrogen can drop anywhere from about 0.6 psi (@32 psi) to around 1.0 psi (@100 psi) per 10 deg F change in temperature.

Don't forget that everyone on the planet is running tires with at least 78% nitrogen already ;-)

 

^This right here, I have noticed the same thing on my truck.

 

Shhhhh.... The tire shops and dealers need to upcharge for N2!

 

Each individual sensor has its own threshold for low pressure based on its pressure during the last reset. There is also a limit to the low threshold which I think is about 25 psig.

In the winter I bump up pressures a touch and reset the system with COLD (not recently driven & low ambient temperature) pressures.

TPMS is a wonderful system with many benefits.

 

The sticker in my truck says 30 psi all around. I left them at 34psi of my cross country trip figuring it might help MPG a little. Around town I will drop them back to 30 psi. Once I get my beach sticker I will be adjusting the tire pressures probably weekly when I get off the sand. For sand use I’ll drop them to 10-13 psi, which should piss off the sensors.

 

I run 35psi year round no issues

 

I think that TPMS is good for certain people. Hopefully, those of us here, check the tire pressure somewhat frequently.
But the TPMS is good for ... Everyone's mother-in-law who never check anything. For them, it's a good 'Hey ... You got a problem.. Pay attention to me' thing. On the other hand, if things go a bit wonky, they can be a bit of a pain.
On another note ... Just for your own sake/good ... One of the few things you shouldn't skimp on is a good tire pressure gauge.
The $2.99 thing they sell on the counter at an auto parts store with the sliding Popsicle stick thing ain't it. That's only good for the glove box. If you can afford hundreds of $$ for accessories, you can afford $30-40.00 for a good accurate gauge.

 

I been trying to keep mine at 32 but the day I took the truck home they were all at 36psi. I think the door sticker said 30 I have to double check that.
I use a 12v compressor and verify with an analog gauge. Tire pressure should be checked at some regular intervals, some more often than others.

I dislike TPMS for the extra cost, complexity and maintenance costs it add to vehicles and it's one more thing you need a shop to fix for most drivers so there is the time taking it in for a TPMS issue alone which cars I learned to drive in and drove for years never had.
The good is it does give you a notice if say you pick up a nail or something and start to loose pressure while driving so you can safely pull off the road to check it out and take action.
My old Liberty used to even monitor the spare and I had a issue with the valve stem on the spare one time. Had it not been for the vehicle TPMS System I may have not noticed till the tires were rotated and what if I needed the spare then and did know it went flat? I kinda wish the Toyota system would include the spare for that reason. I know few people are actually checking it.

 

I don’t like them either, but unfortunately TPMS is good for everyone. That mother-in-law that isn’t checking her tires or maintaining anything..... she’s the one that’s going to have a failure on the road and get into an accident. Us maintaining our vehicles on point isn’t going to do any good when someone smashes into you with their shitty underfilled tires.

What bothers me about the TPMS the most is the difference between manufactures and some requiring special tools to learn and resets. I swap our winter/summer tires over each season and VW has the best “indirect” system where the vehicle uses sensors in the ABS system to track the wheel speed of the tires. Swap over new rims/tires, you don’t have to mess with TPMS sensors or get them recalibrated, unlike on our Subaru where I just stared at the warning light all winter vs buying another set of TMPS and having to take them in for calibration each season.

For those itching to use the 110 bed outlet should have one of these on hand, works great: https://www.lowes.com/pd/Kobalt-DC-...Inflator-Power-Source-Car-Electric/1000092575

 

I agree on the 'cost' thing of it. My son has a 2018 Forester and he just had some new 'HP' Toyo tires put on it. Like $250.00 each tires. Of course they (tire shop) had to 'reset' the TPMS's and that was an additional $100. I'd of thought that when you're spending a GRAND on new This-Is-The-Best-They-Make tires, you'd think they'd at least toss you a bone and include that as a freebie. I'm not sure, but I think they also told him that 'Hey, as long as we have everything apart, and have to reset the TPMS sensors, might as well throw a new set of batteries in them..' At what I'm sure was a 400% markup. The ass-hattery never ends.
I can/could easy live without the TPMS's also. Have for decades.
I remember back in high school and taking Driver's Ed, (1972) they beat you over the head about doing a 'walk-around' before going anywhere. Look at the tires and look to see if anything was leaking. They even said that when parking in a driveway (Like in front of a garage) that you should park backwards, so you could look behind you and see if your brake lights were working, by seeing if the both lit up on the garage door. These things are long gone.

 

A full set of sensors from Toyota for my buddy’s Highlander was $175, and the batteries are good for about 10 years. The sensors need a $8 each “rebuild kit” when the tires are changed to replace the rubber seals, but I’ve never owned anything that needed a $100 reset done.

 

How do you do the re-set?

 

I don't know what the Toyota system is going to be like. I do have experience with the 2006 Jeep Liberty. Those has non replaceable batteries. They all had to be replaced between 2012 and 2014. I got them from Rock Auto for about $25 each so $125 for all 5. Don't remember what they changed me to install them. Could not have been a lot. The tire shop I used was reasonable.
that one it needed programed to add sensors but moving the wheels there was no action needed. If the TPMS light was on after changing or rotating tires it would figure it out after driving a few miles.

I know the Tacoma has the button on the bottom of the dash to reset it.

 

Agree ^ ^

I drive a diesel burner pick-up truck and often have to pull into truck stops for fuel. I see some of the trucker guys with their TPMS...a good size axe handle or other similar persuader stick, whacking on the tires for air pressure... Good to go...

.

 

Just buy the highest quality pencil gauge and be done with it.

 

Turn key to on, hold reset button until the indicator light flashes 3 times, do some driving.

Button is bottom of the dash on the driver's side.

 

I've use them in the past...not as accurate as the digital tire gauge i use now.

 

I remember back in the day .. Not sure if they do it anymore ... We'd stop at a 'Truck Stop' for gas, cuz there was usually a good place to eat there and the truckers used to thump their tires with like a 'mini' baseball bat. They were pretty good at knowing within about 5 lbs what the tire pressures were just by whacking the tires.. LOL!