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Do we need to do anything after releasing tire pressure?

Hello,

My Model Y tires are at 45 psi at cold and always go up to 47(even 48 sometimes) while driving.

Don't like the car to rock around while driving, so decided to release tire pressure down to 42 psi at cold.

After releasing tire pressure, are we supposed to deal with any setting with the car like rebooting or resetting something?

Thanks.
 
For those of us in the cold part of the US, tired pressure drops dramatically when it's single digits outs too. I've had to add about 10 pounds to all four recently. As you mentioned, when the tires warm up, the pressure will increase...so I'll have to remove some air when things heat up to keep all four at 42 PSI.
 

jcanoe

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Oct 2, 2020
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6,108
Maryland
Before you check/set tire pressure the vehicle should have been parked for at least several hours, not out in the direct sun. You will need to use an accurate tire pressure gauge to check the tire pressure. The Tesla TPMS sensors in each tire will turn off whenever you park your Tesla vehicle, the sensors won't wake up again until you start driving. 42 PSI, cold, is the recommended tire pressure on the label on the B pillar by the driver's door. I prefer 43 to 44 PSI. My Model Y has the 19" wheels and the Contiential Procontact RX All Season tires.
 
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Advice pressure is cold measured, and that is simply when air in tire has same temperature as outside the tire.
Advice is given for 65 degrF.
So when measured on a hot day 90 degr F , you have to calculate back the pressure to 65 degr F. It then is still called cold pressure.
Will give a list for 42 psi at the end.
Can make such a list , for every pressure.

Your tires are probably safe ( so they wont overheat , driving at speed) at 32 psi, but let me calculate it first.
The 45 psi is given purely to give the battery more milage.

So 42 instead of 45 will improve comfort, and most likely still safe, but less milage.
Its a choice you have to make , what is most important for you.

Now here the list.
F. / PSI
19 / 37
28 / 38
37 / 39
46 / 40
56 / 41
65 / 42 advice-pressure
74 / 43
84 / 44
93 / 45
102 / 46
111 / 47
121 / 48
130 / 49
139 / 50
148 / 51
158 / 52
167 / 53
176 / 54
185 / 55
195 / 56
F. / PSI
 

jcanoe

Well-Known Member
Oct 2, 2020
5,555
6,108
Maryland
42 PSI is the recommended tire pressure. Tire pressure should be checked, set before the tires have warmed up from the vehicle being driven. In fall as the outside air temperature falls tire pressure will drop about 1 PSI for every 10 degrees colder temperature. You will need to periodically add air to the tires to keep the tire pressure at the desired setting. In the spring, as the outside temperature climbs, you will need to release some air from the tires to maintain the desired tire pressure. You should always measure the tire pressure before driving because the pressure will read higher after driving even 1 mile. After 1 hour of driving on the highway the tires may read 3 or more PSI higher; this is normal. You always want to check/set the tire pressure when the tires are cold (at the ambient air temperature.)
 
You must never lower the cold measured pressure on a hot day to given advice.
In the list I gave, you need the 45 psi when outside 93 degrF to give lesser deflection so heatproduction, then the 42 psi.
Cooling down is also worse then , because temperature-differences between critical temp of rubber and in- and out-side tire air is also less. So then the balance between heating up and cooling down of tires rubber makes it not go over the critical temp. Only once going over that is needed to harden the rubber, and beginning cracks are made, wich tear further in time, untill at some moment the tire blows or treath seperates, with the missery that can go with it.

But this all will probably not happen for the Tesla, with even 42 psi, because probably ( ooh dangerous statement, first calculate it) 32 psi is even enaugh .
 

jcanoe

Well-Known Member
Oct 2, 2020
5,555
6,108
Maryland
You must never lower the cold measured pressure on a hot day to given advice.
In the list I gave, you need the 45 psi when outside 93 degrF to give lesser deflection so heatproduction, then the 42 psi.
Cooling down is also worse then , because temperature-differences between critical temp of rubber and in- and out-side tire air is also less. So then the balance between heating up and cooling down of tires rubber makes it not go over the critical temp. Only once going over that is needed to harden the rubber, and beginning cracks are made, wich tear further in time, untill at some moment the tire blows or treath seperates, with the missery that can go with it.

But this all will probably not happen for the Tesla, with even 42 psi, because probably ( ooh dangerous statement, first calculate it) 32 psi is even enaugh .
I only noted the need to periodically adjust the tire pressure with the seasons: fall, winter, spring and summer. You do not need to check and adjust the tire pressure every time you drive, perhaps only once a month as the seasonal temperature decreases or increases by more than 10 degrees average temperature. The last time I checked and adjusted the tire pressure to 42 PSI* the temperature inside my garage was 35F. I will set the tire pressure again when the temperature inside my garage is consistently ~50F, ~65F and ~80F.

* I actually set the tire pressure to 43 PSI but in this example I used 42 PSI as this is the recommended tire pressure.
 
Last edited:
Is there a point where if I have the tires inflated to 44psi cold (65F ambient) that the pressure becomes unsafe after running for 6 to 8 hours at speed? I am going on a road trip next week of about 320 miles each way and expect to average about 70 mph for the trip. I don't know if makes any difference but there is an elevation gain of about 4100ft.

This morning I drove to the shop that ppf'd my Y and noted TPMS read 47 and 48 psi on the return trip. The trip was just over 31 miles each direction and 85% was at 65 to 70 mph with an air temp of 67F. Just before I typed this I checked the TPMS again and it read 44psi. I confirmed this with my old radial tire pressure gauge and 3 of the 4 tires read 44 and the other read 43.
 

jcanoe

Well-Known Member
Oct 2, 2020
5,555
6,108
Maryland
The maximum tire pressure is molded into the sidewall of the tire. Elevation changes can affect the accuracy of the tire pressure monitor sensor (TPMS). At higher elevations, if you set the tire pressure using an external tire pressure gauge, the TPMS will read lower than at lower elevations as the TPMS is inside the tire, factory calibrated to measure the tire pressure at sea level (14.7 PSI). (An external tire pressure gauge can provide a more accurate tire pressure reading since it automatically compensates for the actual air pressure at your current elevation when measuring the tire pressure, i.e. 14.7 PSI at sea level, 12.2 PSI at 5000 feet elevation, 11.3 PSI at 7000 feet elevation etc.)

The pressure of the air held within the tire is not affected as much by the elevation change as the tire is fairly rigid and does not expand and contract as would a balloon at different elevations. The pressure of the air held in the tire is affected by temperature. After being driven at high speeds a warm tire can raise the tire pressure by ~4PSI. As long as you stay below the maximum tire pressure this should be fine. Even then there is a margin of safety built into the tire. Always check, adjust the tire pressure when the tires are cold (not after driving, not sitting in direct sunlight.)
 
Last edited:
The maximum tire pressure is molded into the sidewall of the tire. Elevation changes can affect the accuracy of the tire pressure monitor sensor (TPMS). At higher elevations, if you set the tire pressure using an external tire pressure gauge, the TPMS will read lower than at lower elevations as the TPMS is inside the tire, factory calibrated to measure the tire pressure at sea level (14.7 PSI). (An external tire pressure gauge can provide a more accurate tire pressure reading since it automatically compensates for the actual air pressure at your current elevation when measuring the tire pressure, i.e. 14.7 PSI at sea level, 12.2 PSI at 5000 feet elevation, 11.3 PSI at 7000 feet elevation etc.)

The pressure of the air held within the tire is not affected as much by the elevation change as the tire is fairly rigid and does not expand and contract as would a balloon at different elevations. The pressure of the air held in the tire is affected by temperature. After being driven at high speeds a warm tire can raise the tire pressure by ~4PSI. As long as you stay below the maximum tire pressure this should be fine. Even then there is a margin of safety built into the tire. Always check, adjust the tire pressure when the tires are cold (not after driving, not sitting in direct sunlight.)

So the max air pressure on the Continental ProContacts on the MY is 51psi. If I have them at 44 psi (at 65F), then with a 4psi increase from high speed driving, I would be at 48, which gives me an addition 3psi as a safety factor. This seems reasonable to me and I can check it periodically as I drive and if necessary let out 1 or 2 psi.
 

jcanoe

Well-Known Member
Oct 2, 2020
5,555
6,108
Maryland
So the max air pressure on the Continental ProContacts on the MY is 51psi. If I have them at 44 psi (at 65F), then with a 4psi increase from high speed driving, I would be at 48, which gives me an addition 3psi as a safety factor. This seems reasonable to me and I can check it periodically as I drive and if necessary let out 1 or 2 psi.
I set my Continental ProContact tire pressure to 43/44 PSI year round. Even if the tire pressure when the tires are warm approaches the maximum tire pressure of 51 PSI the tires have a large margin of safety. Under inflation is much harder on a tire than over inflation; under inflation is the leading cause of tire blow outs. I would not attempt to adjust the tire pressure unless the tires were cold, i.e. had been at rest for at least three or more hours.
 
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