What's the Right Tire Pressure?

[SpudLime]

Same as the Left.

 

[dark cloud]

Centre wear is very uncommon on most of today's tires. It was a big concern in the days of bias-ply tires. What it depends on is the crown radius of the tires. Many tires today have a flat, or almost flat) crown radius and don't exhibit centre wear.

Traction on dry pavement will decrease, but will be better on wet pavement due to the reduction of the possibility of hydroplaning. On ice, higher pressures will wipe away the film of water that covers the ice more effectively, actually increasing the traction (It's the film of water that makes the ice slippery). This is why track pressures are lower than street pressures.

The reason to have track pressures lower are so that the tire heats up more and provides better traction. Hot rubber has a higher coefficient of friction than warm rubber.

 

[dark cloud]

Same as the Left.

But not if the left one is wrong.

 

[nevrenuf]

SO, I park my car in a heated garage, typically about 70 F. I set my tires at 45. I then drive outside into the winter weather and before long, I've got low tire pressure warnings on all four tires under 40 psi.. Should I start at 50 ?

 

[iTech]

45 for comfort, 50 for better range

 

[nevrenuf]

I had the dealer remove the 21's the car came with and put on the 19's for comfort. I'll try the 50 and see how I like it,

 

[Barry]

SO, I park my car in a heated garage, typically about 70 F. I set my tires at 45. I then drive outside into the winter weather and before long, I've got low tire pressure warnings on all four tires under 40 psi.. Should I start at 50 ?

I have the same circumstance as you. I adjust my tire pressure for what the average outdoor temperature is. 1 PSI per 10F.

 

[fallen888]

Same as the left.
Sorry, I couldn't help myself.

 

[arvindm]

I'm rolling with 19" Slipstreams and read the proper pressure is 45 psi. But in my CID display it says my tires are 41 psi when I start driving, and around 30 minutes later the TPMS says they're now at 45 psi instead.

Are my tires under inflated or just right? I just got my car in December.

You are slightly under inflated. Try keeping cold pressure to 42 psi and warm pressure may go up 4-5 psi depending on road and ambient temp.

 

[Midnightsun]

Typically in cold weather winter regions, 3-4 psi higher than indicated is the norm when adjusted in a heated garage. On cars I have had in the past it was not uncommon to get low pressure/flat tire warnings when leaving the garage into -25C temps.

Tire pressure recommendations are based on several factors but the most important one is weight of the car the tires will be used on. Teslas (EVs in general) weigh a ton and therefor the higher tire pressures we see on them compared to the average ice car which is usually around 32 to 35psi. Most European manufacturers have 2 different pressures depending on if you travel full or empty. In the case of my Mercedes, the recommended rear pressure with 3 passengers is 3 psi more as opposed to travelling just 2 up front. They have it right.

Door jamb figures are the one to use, bump it up a bit in very cold temps. Bump it up a few psi on the rear wheels temporarily if fully loaded on a long trip.

 

[Gadget-X]

I have 19" slipstreams. The proper Tesla air pressure is 45psi at 70 deg F. Seems everyone has a formula. Right or wrong that is what I inflate mine too.

M

 

[arvindm]

I'm rolling with 19" Slipstreams and read the proper pressure is 45 psi. But in my CID display it says my tires are 41 psi when I start driving, and around 30 minutes later the TPMS says they're now at 45 psi instead.

Are my tires under inflated or just right? I just got my car in December.

Just right. Temperature build up due to road friction means you will have an increased pressure inside the tire. Expect PSI to go up by 3-4 points. Its normal

 

[NickFie]

Just right. Temperature build up due to road friction means you will have an increased pressure inside the tire. Expect PSI to go up by 3-4 points. Its normal

I disagree. Tire pressure is specified for cold - not recently driven - tires. It’s impossible to know how much the pressure will rise with use. Speed and load are the big factors.

Expect tire pressure to rise above cold pressure at highway speed. That’s normal, the tire and wheel are designed for this.

If you start with below-spec tire pressure, the sidewalls flex more. That generates heat that raises the tire’s air pressure to a comforting level. However, excessive sidewall flex heats and weakens them raising odds of a blowout.

Also, below-spec air pressure reduces efficiency.

 

[Gadget-X]

I'm rolling with 19" Slipstreams and read the proper pressure is 45 psi. But in my CID display it says my tires are 41 psi when I start driving, and around 30 minutes later the TPMS says they're now at 45 psi instead.

Are my tires under inflated or just right? I just got my car in December.

Just right. Temperature build up due to road friction means you will have an increased pressure inside the tire. Expect PSI to go up by 3-4 points. Its normal

----------------------------------------------------

You can check every tire manufactures procedures. They ALL say "If your vehicle recommends 45psi, this is cold psi that means 45psi before you drive". Weather can effect pressure by 2-3 psi. I always check our vehicle PSI outdoors after car is at ambient temperature (we have a heated and cooled garage). Here in NW Florida our temps usually range from Mid 20s F to as much as 100 F. As general rule I check when temps change 20% or so. Usually adding air as temps go down and deflating as temps raise. This helps tire efficiency and will make your tread last longer. Very helpful to our Tesla vehicles that wear tires.


M

 

[dark cloud]

Just right. Temperature build up due to road friction means you will have an increased pressure inside the tire. Expect PSI to go up by 3-4 points. Its normal

----------------------------------------------------

You can check every tire manufactures procedures. They ALL say "If your vehicle recommends 45psi, this is cold psi that means 45psi before you drive". Weather can effect pressure by 2-3 psi. I always check our vehicle PSI outdoors after car is at ambient temperature (we have a heated and cooled garage). Here in NW Florida our temps usually range from Mid 20s F to as much as 100 F. As general rule I check when temps change 20% or so. Usually adding air as temps go down and deflating as temps raise. This helps tire efficiency and will make your tread last longer. Very helpful to our Tesla vehicles that wear tires.


M

Just my experience added to the above several comments: In summer in the 20 degree Celsius garage my tires are set at 45. After some highway driving in the summer they have risen 5 psi and all show 50-51 psi if it the ambient temperature is 35 degrees. This is my normal, and I am fine with this.

Sometimes winter surprises us in late October, and the same tires frequently throw TPMS errors, as the -10 degree air now has the tires at 38 psi. So yeah, they have dropped by 7 psi. Depending on the forecast I either add air, or just change them over to the winter all-weather (snowflake) Nokians. Inflating tires with nitrogen instead of just air will be more resistant to this, but this is of course inconvenient.

41 psi inflation? It could be fine, if one likes that less-efficient soft feeling, like a guy who loved his Cadillac, but what if that small chance the driver loads up 5 people in the car, and luggage in the boot? There is risk.

After 220,000 km and 5 different brands of tires on this Model S, I agree with the manfacturer's suggestion that 45 psi cold* is still the optimum inflating pressure. (*Cold = car exposed to ambient temperature, in shade, undriven for at least 12 hours)

 

[2101Guy]

That's because there is no one right answer. Use the general principles above and then watch what the tires do.

I go with 42psi cold. After ~9k miles, I appear to have very even wear across the entire tread of the tire on all 4's.