websailor

So today I decided to try to equalize the air pressure in my 4 tires. They ranged from 32 to 36 on the console display. I also wanted to try to identify which tire was #1 on the display, #2, etc. (I've read the various threads about this particular Lexus exercise in frustration.)

Currently I'm just about as frustrated as I was before!!! I got three tires set to 35 psi. Great I thought. Then one of them changed to 34...and then a bit later to 35 again. Then one of the others changed by 1 psi. While it is possible that I was just on the verge of 34-35, I doubt that two were.

Nevertheless, I added some air to the one tire. It did not appear to make a difference.

So then I concentrated on the one tire that was at 37 psi, letting air out. It would NOT change. My trusty hand gauge said it had changed, and my eyeballs say it changed, but not the TPMS display,, not even waiting quite a while. I even did a TPMS reset and it stayed the same (but one of the other tires then read 32 psi...aaaarrrrggghhhh!!!!).

It did finally change to 36 psi when I gave up and drove the car back into the garage.

So should I care if 3 tires read 35 psi most of the time and one reads 37 psi (or maybe 36, I think I need to drive the car some to see what it settles on)?

What do other people do - do you watch the TPMS to see if the tire pressure is okay? Do you use a hand gauge at all?

Do you think the TPMS is accurate to within 1 psi, 2 psi, or at all, etc?

I know I can take it in to the dealer and let them use up their huge Nitrogen tank to get it correct - is that the best solution?

SteveCraig

At the end of the day, the old style mechanical gauge is my own best bet. The TPMS units operate in a fixed range. Anything below the range will show as an issue on the dash. Believe it's about -8 psi from the set point.

I like to tinker with my own vehicles & that includes changing the tires at seasonal intervals.I have a floor jack & a decent torque wrench which makes it easy.

Changed the tires over on the RX about a month ago. Existing TMPS units missing didn't register as an issue for 3 days. They were still in the Winter tires, in the garage. The TMPS in the Summer tires had not yet been registered with the car's systems. Dealer reset the computer, washed it, vacuumed it, provided the coffee all at N/C.

The air we breath is already 78% nitrogen, I don't buy the tire fill deal. If they offer it at N/C, fine.
Brother in-law bought a 1 year old Volvo wagon a couple years back. Charged him $200 for the nitrogen fill, he thought he was getting a deal.

vlad_a

I do not use TPMS at all for my winter set and only use it for reference during summer. Digital hand gauge is the best. I use 2-gal air compressor I have in the garage and fill tires when they're cold.

kitlz

Ernie, trying to get all four tires to read the same on TPMS display is not worth it. I find the pressure is off by at least a pound. It's higher than the manual tire gauge reading which I use at least once a month. Sure helps that the Pirellis don't need adjustment very often unlike the Dunlops they replaced. Those needed air every few weeks.