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Discussion Starter · #1 ·
I have a new 2022 Ascent Touring with 1150 miles on it. I have always been anal with my tire pressure and balancing of the tires. I never had a display that gave me the actual whole PSI of the tires, but was interested in viewing the pressure of the tires on the display after I "thought" I balanced them to 33 psi. (Did it in the morning before the car was driven.)

As I drove the car around locally I noticed that the pressure would vary and not remain balanced. The next day, I would measure the cold pressure again and the tires appeared balances as per my gauge, the TPM readout would be different. Thinking it was the gauge, I bought an AstroAI Digital. The AstroAI could read in 0.1 psi, but the manufacture of the valve nozzle actually prevented the setting of the tires to the 0.1 psi because it was difficult to keep the gauge aligned. I settled on balancing to 0.5 psi.

Although I could balance the tires with the gauge to within 1/2 psi, the TPM could be off by 1 PSI. as while driving.

Am I wasting my time with this?

Thanks.
 

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The short version is that the TPMS is very accurate for the method that it uses to determine tire pressure. The bad news is that it's not as accurate as you are trying for. Also, tires will never be the same PSI to the accuracy you are hoping for due to variables like loading, rolling resistance or even two tires being on the sunny side of the car. Heating and cooling is the biggest contributor to your pressure changes.
 

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I check the TPMS every once in awhile out of curiosity and it always varies but I'm looking for a big difference. I would think the car would let me know anyways. I generally check the tire pressure every week for both Subarus, cold and outside, out of the sun, and having an idea what the highest temperature of the day will be.
 
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