wierd model s tire issue

[meomyo]

New michelin cross climate 2 on the car..drives great...but whats odd is the left side of the car tires keep reading less tire pressure. I fill to 45 and they show 42..and then it can go to 38 and the red lettering shows up ...Drivers side front and back. Its odd as the rims are fine but could the tires be defective? When rotating there you can put them on the other side only front to back because of the tread.
Anyone else have this happen? No nails in the tire..i have taken it back to discount tire and they did replace 1 free as it did have 3 nails in it in the same spot which was odd..but this pressure loss still happens on the left side??? Could the tmps valves just be bad??? I was told they oftern can read 3 psi +/-. Its making my gf go crazy and wake me up to check the pressure for her at 4 am before she goes to work..lol...She seems to think its the tires somehow...

 

[ShawnA]

Hi @meomyo ,

You do not mention the model year of the car...
It is important due to TPMS changes - 2 different types before and after 2015...
The TPMS may be need to be replaced if the car is 5 to 6 years old.
(Their batteries can last from 5 to 7 years.)

The change in ambient temperatures due to the season change makes everyone's
TPMS read lower...

You should establish a correspondence between your tire gauge and the TPMS.
If they are not the same that can introduce errors.

TPMS should be very accurate. The pressure will change due to sunlight
heating the tires. I have seen mine read 4 psi higher with the car parked
in the sun.

With everything in mind you need to make sure you do not have a leak or leaks.
A spray bottle of soapy water on the tire and valve stems can show a leak.

Good luck,

Shawn

 

[Ostrichsak]

Easy answer... Elevation.

I see that you're in Colorado and assume you're at a similar elevation to me. It's a long explanation but basically TPMS sensors at this elevation will always read about 3psi low.

It's maddening to me that Tesla can't adjust for this in all of their algorithms and settings to make it simple for the car to know where the elevation is and adjust TPMS readings accordingly.

This would be especially helpful since the low pressure warning comes on at 39psi which is actually 42psi in our cars at this elevation. It's also especially common given our shoulder months in the wild temperature swings that we experience which greatly impact tire pressure.

Should be a really simple algorithm to add to the coding to gradually adjust those up as the elevation rises. I'm sure it's on the long list of coming features. /sarcasm

Until that day comes we're just stuck playing and annoying & avoidable game in Colorado.

 

[meomyo]

its a 2017 model s 75d.

 

[meomyo]

Easy answer... Elevation.

I see that you're in Colorado and assume you're at a similar elevation to me. It's a long explanation but basically TPMS sensors at this elevation will always read about 3psi low.

It's maddening to me that Tesla can't adjust for this in all of their algorithms and settings to make it simple for the car to know where the elevation is and adjust TPMS readings accordingly.

This would be especially helpful since the low pressure warning comes on at 39psi which is actually 42psi in our cars at this elevation. It's also especially common given our shoulder months in the wild temperature swings that we experience which greatly impact tire pressure.

Should be a really simple algorithm to add to the coding to gradually adjust those up as the elevation rises. I'm sure it's on the long list of coming features. /sarcasm

Until that day comes we're just stuck playing and annoying & avoidable game in Colorado.

yes in colorado i do get that. I want to fill to 48 vs 45 to make up for the 3 psi..So this am filled them all to 45 for her and we will see when she gets home later what they read.

 

[Ostrichsak]

yes in colorado i do get that. I want to fill to 48 vs 45 to make up for the 3 psi..So this am filled them all to 45 for her and we will see when she gets home later what they read.

Don't overinflate your tires to make up for inaccurate gauges and measuring devices. You now know that 42psi displayed inaccurately is actually 45psi which is where you want to be. Inflating to 48psi is a surefire way to end up with a blowout next spring when, on the highway and as temps increase, your tires are actually running 55psi as you hurtle at 80mph down I25. So the band-aid fix is to inflate to 45psi (42psi indicated) and then making sure you're on top of your inflations so it never shows 39psi (42psi actual) to avoid the dreaded warning. That's the easiest solution unless you can convince Elon via Tweet or whatever to fix these cars via small software update that would be super easy to implement.

 

[meomyo]

thanx for that...!!

 

[Russell]

Check the valve core. It could need retightening or cleaning.

I had a wheel that would consistently lose a few lbs every month. I took out the core and made sure there was no debris on the seal then put it back in.
Never had a problem since.