Why 45 psi?

[Scannerman]

Did your car come with the Goodyear tires? My 60 did and had 42 psi on the placard. When I replaced the tires with Michelin Primacy last year the service center said 45 psi is recommended for those tires. They couldn't change the door placard but put a note in my service record to ignore the door placard and inflate to 45.

Has anyone heard from an official Tesla source as to why they are recommending 45 psi?

Scannerman

 

[GSP]

I was beginning to have excessive center wear at 50 psi. Tesla looked at it and agreed and lowered the pressure back down to 45 psi.

Interesting. Do you have the 19" Michelin Primacy tires?

GSP

 

[jerry33]

Good post ... here is another guide for those who spend a fair bit of time at the track... Not for Road Use

To add to the hydroplaning bit: Hydroplaning occurs when the pressure in the wedge of water between the tire and the road surface equals or exceeds the tire pressure.

 

[jerry33]

Interesting. Do you have the 19" Michelin Primacy tires?

GSP

FWIW, I get very even wear on the 19" Primacy at those pressures (50 psi). The Goodyears didn't last long enough to tell as they were on in the early days when Tesla didn't get the alignment right. Whether those pressures will wear in the centre or not depends upon the crown radius. If it's small, that could happen. Large, unlikely. Many modern tires have an almost infinite crown radius (aka flat).

 

[msnow]

Got it, thanks. The display doesn't fill in any values for tire pressure. Maybe it takes a bit.

Yes, it takes about 10-15 minutes of driving around.

 

[sorka]

Interesting. Do you have the 19" Michelin Primacy tires?

GSP

Yes.

 

[Magic1010321]

All tire pressure recommendations are based on a set of assumptions. The basic four are:

1. The ambient temperature is 18C (65F). If it's higher than that you need to adjust the pressure upwards.

2. Speed. The GY chart (and all other charts from the tire manufacturers (as far as I know) are based on a 65 mph sustained speed. If you run faster than that, then you need to up the pressures.

3. Load. For cars the load that the pressure recommendations are set at are for what the engineer thinks is going to be normal for that car--not necessarily the GVW.

4. A daily pressure check at the start of each driving day. (Don't shoot the messenger.) If you don't check every day, then you need to adjust the pressures upwards so that you never go below.

In addition there are factors particular to each car, such as handling and weight transfer (to name a couple--there are more).

Another list:

1. Higher pressure reduces heat in the tire which causes tire failures and shortens tire life.

2. Higher pressure reduces the chances of having uneven wear.

3. Higher pressure provides better transient response in an emergency situation.

4. Higher pressure reduces the chance of hydroplaning.

5. Higher pressure is required when the temperature is above 65F (18C) or below 65F and inflated indoors.

6. Higher pressure is required so that the pressure does not fall below the minimum if you don't check pressures each day before you drive.

7. Higher pressure is required if you carry more load than the car was designed to normally carry (note that this might be less than the GVW--it could be only one or two passengers).

8. Higher pressure provides better traction in most, but not all, on-road winter conditions.

9. Lower pressure increase ride comfort, which is highly subjective and probably depends a lot on the amount of "natural padding" present

10. Lower pressure reduces vehicle damage during off pavement usage.

Note that track use--where you adjust the pressures to get the most contact area is a whole 'nuther subject, and basically not applicable to normal driving (unless you like buying tires frequently).

Why would you need more pressure when its hotter outside? Or going faster? When it's hotter the pressure will be higher when you're going faster youre producing more heat and thus more pressure...my logic and basic gas law knowledge tells me you would want to put less air pressure...other wise you would be ”over inflating”