So my 2011 LX570 was driving a little rough and I noticed that the tires were over inflated. According to the gauge on the cluster, my tires were ~40 PSI. Per the label in the door jam, they are to be inflated to 33 PSI COLD. I let some air out of the tires and checked each one (minus the spare) with a manual gauge and they all read 33 PSI COLD. I turned the car on and watched the gauge as it said 'checking' during the reset. They all came up as ~36 PSI. After several days, they are now all over the board, some say 36, some are 38. Is there something wrong with the electronic gauge on the dash, is there a reset function I need to perform, what? Any advice would be helpful. Thanks.

 

Mine does it too. Start at 33 goes anywhere from 34-38, depending on weather/driving/speed etc. They usually settle down to within 1 psi after driving for 20 minutes.

 

Even when the tires are cold, they are now all over the board too, i.e. right when I start the car, they no longer even register 36 PSI, they are totally random.

 

When I use my good tire gauge the readings are different from the vehicle. My gauge reads 32 psi and the car is 33. I don't know which one is more accurate but don't really care about 1 psi. Inflate or reduce psi till the car is happy or use a gauge to initially set the psi for each tire. Do a tpms reset and montior.

If you use a gauge at least you should get a consistent pressure reading as opposed to using four different sensors to set up the pressures...if that makes any sense.

There is a possibility that the TPMS units are going south.

 

Yes, my manual tire pressure gauge shows ALL TIRES at 33 PSI. It is the TPMS that is showing 36 PSI or some other random PSI outside of the manual gauge. Is there a way to reset the TPMS to see if that fixes the problem?

 

I have a very accurate Longacre gauge that I use for motor racing and also use to set the tire pressure in my 2017 LX. I always set pressures before the vehicle has been driven and before the sun may have had an impact on heating the tire and changing pressure. I have been impressed with the accuracy of the TPMS in my 2017, it is spot on. All of my older cars with TPMS have generally read 3 - 5 psi higher than my gauge.

I would do a reset of your TPMS system. Drive around until the pressures reappears and then check pressures again the next morning and equalize tire pressures. If your tire gauge is off, it will be consistently off (unless it is visibly damaged) but the tire pressure reading in your dash should also remain consistent. If you have variable dash readouts after driving for 20 mins or so, then one or more of your TPMS sensors is inaccurate.

Stating the obvious but your tire pressure will change with ambient temperature changes, sun exposure and driving. I find that after a run on the freeway tire pressures increase about 4 psi overall. The fronts are often 1 psi lower, I assume as they are exposed to fresh air cooling the tire vs the back tires being in dirty air. If you are not confident in your pressure gauge accuracy, either try another or start to calculate your MPG. A couple of PSI off will lower your fuel economy by 1 - 2 mpg, I have found.

 

I check my tires weekly and the indicated tire pressure on the dash varies as much as 2-3 pounds. Does this on both my LX and RX units.

I trust my handheld air gauge the most. Re-setting the TPMS will not fix this in my experience. It is just a difference in calibration on the TPMS sending units.

 

^^^^^ This.

I use an accurate gauge and set my tires only in the morning before the car leaves the garage or the door is opened so as to ensure no sun shines on the tires. After setting pressures to desired reading to the nearest 0.1 psi, the gauge on the dash always matches the set pressures. Drive around the block, and the values on the dash will be different because the tire pressures will be different.

 

You guys using nitrogen? It's amazing how worry free tire pressure has become.

 

I use 80% nitrogen.

 

My 2015 TPms is spot on accurate with my manual gauge

 

I have an accurate ARB mechanical tire gauge and a set of quality aftermarket TPMS. They are within 1bar (about 1.5psi) of each other. But I always trust the ARB mechanical gauge for 4 wheel uniformity.

 

Beyond around 80%, excess nitrogen begins to affect your wallet with no corresponding effect on tire pressure.

Sucker bait, ala' Amway.

 

I, too, use about 80% nitrogen in my tires. It's free aside from the electricity used by the pump. I have a trusted Sears Craftsman digital tire gauge I bought on sale for $13.95+tax. LED light, backlighting display and all. I lose 2 psi every 2 months. Anything more than that, my OCD alarm goes wild.

 

I check tire pressure weekly for both winter and rest-of-the-time tires. I may lose a pound or 2 a week. The TPMS is great for letting you know if you've got a serious leek, if / when it works.

My '13 200 series cannot remember it's connection to any of the wheels with oem wheels, and will not accept Toyota transmitters on the winter tires mounted on Tundra wheels. The last service writer I worked with called the system a "POS". I don't disagree.