Tire warning but good pressures

[MichaelW]

got this warning today. Went over a bit of a rock yesterday but no issues. Anyone know what the issue could be?? Pressures look ok.

 

[WildRide47]

got this warning today. Went over a bit of a rock yesterday but no issues. Anyone know what the issue could be?? Pressures look ok.

View attachment 24947

Pressures are not OK. Should be 49 lb on the 19 inch tires and at least 42(preferably higher than that(I keep it at 45) on the 21 inch tires.

 

[MichaelW]

Pressures are not OK. Should be 49 lb on the 19 inch tires and at least 42(preferably higher than that(I keep it at 45) on the 21 inch tires.

Really? Wouldnt I get all 4 warnings?? I haven’t touched the tires since I took possession of the car.

 

[TakeDuo]

I have had the same. I assumed the TPMS was reading in decimals not displayed. Like the yellow was 38.2 psi and the others maybe 38.8 psi thus triggering the warning being below a threshold. This is how I rationalized it.

 

[DrZorro]

My Audi occasionally does something similar... Usually it happens if one or more of the tires is borderline low (but still within normal range) and then you go from a hot day to a cold morning the next day (Welcome to Tx), it tends to trip the sensor if it dips below a certain threshold even if you start driving the car and the tires warm up and the pressure goes back in to the normal range. Usually you either have to fill it back up over a certain other threshold or reset TPMS system in the menu.

 

[Bobby]

Pressures are not OK. Should be 49 lb on the 19 inch tires and at least 42(preferably higher than that(I keep it at 45) on the 21 inch tires.

Yes, follow this advice!

 

[borski]

Yes, follow this advice!

I still like 42 on the 21s over 45 but otherwise totally agree.

 

[borski]

I have had the same. I assumed the TPMS was reading in decimals not displayed. Like the yellow was 38.2 psi and the others maybe 38.8 psi thus triggering the warning being below a threshold. This is how I rationalized it.

You are correct. The API returns it to three decimal points, albeit in bar, rather than PSI.

 

[hmp10]

Really? Wouldnt I get all 4 warnings?? I haven’t touched the tires since I took possession of the car.

I don't know how long you've had the car, but tires can easily lose 2-3 pounds of pressure per month, even just sitting in a garage. Tire pressure should be checked regularly.

Also, you said you hit a rock. It could be that the tire pressure sensor mounted in that wheel got jarred, and the software just froze on the existing pressure reading but is sending a warning of a malfunction.

 

[joec]

I got a warning the other day on one of my tires. It was reading 42 (I have 19s). The others were reading just above at 43. I pulled over and checked my actual pressure using my own guage. They were all actually at 45. Since I had just started driving after a few hours of it sitting, I figured it was safe to top them back up to 49.

Of note: I had climbed almost 2000 ft that morning to do a hike, and it was somewhat cold for California. About 45 degrees outside.

By the time I came back down to sea level and had been driving for a while, the pressures were all reading normal again.

2 lessons:

- The TPMS in any car are meant to warn you of a sudden drastic drop in pressure more than anything else. They are anything but accurate.
- With an EV, always carry with you a way to get your tires back up to optimal pressure. I have a battery operated air pump that fits nicely in my lower trunk. Temperature and elevation will certainly cause your pressures to change.

I thought maybe I had sprung a slow leak on the one tire that gave me a warning. Until I saw that all four tires were reading below normal. Then I figured it was the elevation and temperature. I still topped them off, anyway, just for good measure.

 

[Cosmo Cruz]

Temp. swings of more than 30 degrees F in less than a day happen in PA = as much as 4 or 5 psi ... which is why one checks tire pressures "cold " (out of sun, haven't driven for 6 hrs.) . I run the 19" A/S at 49 psi.... and the 21" summers at 45 psi. It was a bold move to dare the 21"s where I live ... but if you always drive very slowly whenever you have the 21" on you can mostly dodge the road hazards.

This is why everyone posts their location in their profile.

We can't assume everyone lives where Borski does: perfect roads, no dramatic temperature swings, no snow ever.

 

[victoryroad]

Of course, Cos is right. Expect lower tire pressure as the ambient temperature drops. Oddly, only one flashed a warning, and not all. I run with a rechargeable air pump that fits in the glove compartment. 19's should be 49 psi which will drop after sitting in the colder temperatures and rise when the tires warm up.

 

[hmp10]

Oddly, only one flashed a warning, and not all.

That's why I think it is a pressure sensor malfunction. On a recent road trip, we had a sensor break loose from the zip tie a moron at a tire shop had used to secure it. We got no tire pressure warning from that corner of the car. I only found out the sensor had broken loose when I got out of the car and heard an odd rattling noise in a wheel as my partner drove the car off. When I called up the tire pressure screen in the car, only then did it show a message that a sensor signal was disrupted.

In short, @joec is right. Don't rely on the TPMS to tell you anything other than you've had a precipitous drop in tire pressure . . . and maybe not always even that. TPMS is no substitute for manually checking pressure at each tire on a routine basis at least monthly.

 

[ColonelBadger]

Interesting. I just pumped up my tires cold (because temps have dropped in to the 20's and 30's here) to 49psi. Next morning checked what the car was reporting after about 15min of driving and they were all exactly 49psi (They were around 45psi before). So either my TPMS is accurate or my electric pump is inaccurate!

 

[Pragmatic]

I have the 19 Pirelli's. I took delivery January 3, 2024. Adjusted tire pressure to 49 when I got home. By September they had dropped to 46 so I brought them back to 49.
I'm leaving for VT so I figured I better check them. They were 49, 47, 47 and 46. So in 17,000 miles and 11 months I've only added air twice.

 

[victoryroad]

FWIW the Pirelli Sottozero 19s hold pressure equally a well as the AS Pirellis. Winter compound tires in VT and CO are well advised from Nov to April.

 

[Leftlane]

You lose approx 1 lb psi for each 10 degree drop in the ambient temps.

 

[borski]

Temp. swings of more than 30 degrees F in less than a day happen in PA = as much as 4 or 5 psi ... which is why one checks tire pressures "cold " (out of sun, haven't driven for 6 hrs.) . I run the 19" A/S at 49 psi.... and the 21" summers at 45 psi. It was a bold move to dare the 21"s where I live ... but if you always drive very slowly whenever you have the 21" on you can mostly dodge the road hazards.

This is why everyone posts their location in their profile.

We can't assume everyone lives where Borski does: perfect roads, no dramatic temperature swings, no snow ever.

Definitely not perfect roads; I'm just careful on them.

But yeah, it doesn't really get below 45 ever, and snow only exists in Tahoe.

 

[MichaelW]

Thanks for all the advice guys. Pumped them up to 45psi and the issue “seems” to be gone.

 

[FM7]

I still like 42 on the 21s over 45 but otherwise totally agree.

That's cold right?