mrblister

Hi

I have a 2004 gx470 and in july I replaced all 5 of my tpm sensors . Pressure was set to 32 lbs as listed on the door. The other day we had a drop In temp to approx. 35 degrees and I found my TPM light was on. I checked all 4 tires and found the pressure dropped to 28 lbs. I aired them up to 34 lbs and light stayed on. I then dropped the spare and found that at 28 lbs as well. I aired that up to 34 lbs and the light went off. Is the trigger drop in pressure of 4 lbs triggers the alarm light seems to be a very small spread in air pressure to trigger the alarm. Any one have any info on this

chiph9

From what I understand, it's the pressure loss plus the rate of pressure loss that triggers the "Hey, you've got a flat tire" light.

So far as pressures, I've had good luck running 2 lbs over the door sticker. I get even tire wear, and a slightly firmer ride.

Chip H.

winterbeat

Put 38psi in your spare so that you don’t have to mess with it in cold weather. Road tires need to be aired up for the winter. They will drop at least 5psi as you go from 80 degrees to 20.

MTD1

I have had the same problem this past week. I bought new rims, added AT tires and new TPM. They were fine for about 3 months. The temp dropped this past week and the light came on. Interesting enough it came on after an hour of interstate driving. Spare tire maybe? Pulled over. increase 4 tires from 32 to 34. Has been randomly on and off for the last week. I guess I'll drop the spare this weekend and increase the pressure there and see what happens? Always open for Advice.

IanB2

There's a good chance your spare is the problem, if you park in a garage where it's warmer, then once the spare cooled and pressure dropped you started having issues.