Checking Tire Pressure

[texex91]

the max PSI is max cold pressure which accounts for expansion when the tire warms up.
in many places you can fill with Nitrogen instead of air (78% Nitrogen, 21% oxygen). (the local Sam's club uses Nitrogen when filling tires.) with Nitrogen you get less expansion and less moisture in the tire, which is a good thing.

I always fill my tires with nitrogen. Makes a big diff with changing temps. When s arrives plan to do the same. Surprise Tesla doesn't do it standard. Heck, my Chevy dealer even does it now. All Porsches, etc have nitro that I've owned.

 

[mknox]

in many places you can fill with Nitrogen instead of air (78% Nitrogen, 21% oxygen). (the local Sam's club uses Nitrogen when filling tires.) with Nitrogen you get less expansion and less moisture in the tire, which is a good thing.

IMHO, Nitrogen is a scam. Air is already 80% nitrogen. The only reason I had nitrogen in my last car's tires was because it came with the unlimited tire hazard warranty I bought (I have the worst luck picking up screws/nails and getting flats -- not looking forward to my first Model S flat with no spare on board!).

 

[Al Sherman]

You actually check the pressure. The TPMS only alerts when the tires are dangerously low and by then the tire has already likely sustained some damage. Use a high quality gauge such as Longacre 50406 or 50404 and don't trust anyone else's gauge. Check the pressures first thing in the morning before driving more than a mile (slowly).

Good news is that real time pressure will be in the next release.

Got it! But is this gauge adequate? It was quite a bit less expensive than the Longacres. Also, my door says 42psi for the 21". That's what I'm doing. Correct? I've been checking every 2-4 weeks and the pressures are usually low from 1-3 psi. Normal?

 

[teslasguy]

Recommended pressure is 42 lbs for 21" wheels and 45 for 19" wheels.

 

[jerry33]

Is it not rather risky to keep the tires at the maximum PSI?

When you actually start driving and the tires warm up, the air will expand and inflate over the maximum pressure, increasing the risk of a blowout.

NO, NO, NO!!! You have two choices:

1. You can put less air in the tire and while driving the flexing of the tire will increase the temperature of the tire which will increase the pressure.

2. You can put adequate air in the tire to start with.

In either case the tire will be at the same pressure after an hour or so of highway driving, however the tire that started out with the lower pressure will be far hotter.

Tires are designed for this, that's why it specifically says "cold inflation pressure".

Blowouts generally occur on tires that aren't inflated enough.

Heat, not pressure, kills tires.

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Got it! But is this gauge adequate? It was quite a bit less expensive than the Longacres.

I have found that cheap gauges are, well, cheap. I had one that actually fell apart from the vibration in the car. Quality gauges will last a lifetime and can be calibrated.

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I always fill my tires with nitrogen. Makes a big diff with changing temps. When s arrives plan to do the same. Surprise Tesla doesn't do it standard. Heck, my Chevy dealer even does it now. All Porsches, etc have nitro that I've owned.

Nitrogen inflation is mostly a scam. The only reason that temperatures changes make a larger difference is that sometimes straight air isn't dry and the water vapour expands more than gas. I will not go to places that sell nitrogen inflation because they will likely cheat me in some other way too.

There are a few legitimate reasons for nitrogen inflation:

1. Underground vehicles and high altitude airplanes use nitrogen inflation because if a fire breaks out, the air in the tires won't add any oxygen to the fire. (There is already plenty of oxygen above ground, so it's a non-issue for road vehicles.)

2. High end racers use nitrogen because it's dry and they can tune their suspensions to get that extra 1/100th second off the lap time.

3. Low end racers use nitrogen because many small tracks don't have electricity in the pits, and nitrogen is as cheap and safe as any other solution.

 

[ZBB]

Recommended pressure is 42 lbs for 21" wheels and 45 for 19" wheels.

Not anymore... 19"s now ship with labels stating 42 PSI (and the label has the correct tire size). My car was delivered 3 months ago and has that label...


FWIW, I got the tire pressure warning a week and a half ago. Found all 4 tires at about 40. Went ahead and raised the pressure to 44 cold since that is still well below the max listed on the sidewall (50 I think). I've traditionally put 2 PSI over the label on my cars (or 4 over if I need to fill when hot -- I then re-check when cold and normally check very close to 2 over).

 

[Mayhemm]

Tires are designed for this, that's why it specifically says "cold inflation pressure".
Blowouts generally occur on tires that aren't inflated enough.
Heat, not pressure, kills tires.

Good to know. This is not what I'd been told in the past.

Would you recommend keeping tires at max pressure then?

My tires only list a "maximum inflation pressure" of 51 PSI, not a "cold inflation pressure". Are these the same thing?

 

[caddieo]

Not anymore... 19"s now ship with labels stating 42 PSI (and the label has the correct tire size). My car was delivered 3 months ago and has that .

Hmmmmm. I won't be able to check until I get home from this trip, but I'm pretty certain the label on my 19-incher (delivered 7/19) said 45 lbs.

 

[dirkhh]

Hmmmmm. I won't be able to check until I get home from this trip, but I'm pretty certain the label on my 19-incher (delivered 7/19) said 45 lbs.

Door label in my S60 (VIN 11623) states 42psi for my 19". Had low pressure warning this week with all wheels showing 39 or 40 psi when checked.

 

[Effects]

I have used the Accutire digital for years on my cars and motorcycles. Extremely accurate and reads exactly what my TPMS says on my Acura TL. Small enough to put in your pocket.

Accutire Professional Metal Digital Tire Pressure Gauge

 

[jerry33]

My tires only list a "maximum inflation pressure" of 51 PSI, not a "cold inflation pressure". Are these the same thing?

Yes they are. Someplace it will say cold (there is about five pages of lawyer talk printed on each tire). And sorry about the yelling, that's kind of a hot button with me as I've been fighting items that were kind of correct for bias-ply tires but have little meaning for radial tires for more years than I have fingers and toes.

 

[neroden]

Not anymore... 19"s now ship with labels stating 42 PSI (and the label has the correct tire size). My car was delivered 3 months ago and has that label...

Oh, wonderful. I'm going to have to call Tesla to ask what the ideal inflation pressure to use is. My door label says 45 psi.

I got aftermarket snow tires and I don't know what to inflate them to. They have a plenty-high max inflation pressure, but what should I inflate them to?

 

[PhilBa]

vin 13435 P85 w/19" door plate says 45 psi delivered 6/28

 

[Musterion]

Solution to 42 vs 45 psi on 19" wheels

Hi all, I believe that 60 kWh cars are being spec'ed at 42 psi and 85 kWh cars at 45 psi for the 19" wheels, due to the weight difference of the battery. At least, that would make all the recent posts self-consistent with the cars I see listed in the signatures, including my own. Also I would hazard a guess (not listed in signature) that ZBB has an S60 just from the 42 psi spec label on 19" wheels.

 

[Tacket]

I've got a 60 with 19" and 42 psi listed (delivered 06/13).

 

[kevincwelch]

VIN 4xxx. 19 inch wheels: 45 psi. Goodyear.

 

[caddieo]

Hi all, I believe that 60 kWh cars are being spec'ed at 42 psi and 85 kWh cars at 45 psi for the 19" wheels, due to the weight difference of the battery. At least, that would make all the recent posts self-consistent with the cars I see listed in the signatures, including my own. Also I would hazard a guess (not listed in signature) that ZBB has an S60 just from the 42 psi spec label on 19" wheels.

Did a quick review of previous posts and I think I agree with you. 60kwh=42 and 85 kwh=45.

 

[Merrill]

On a cooler evening if I have 42 the low tire pressure light comes on. I keep mine at 45.

 

[dhanson865]

Something to keep in mind for those buying a gauge you should get one that goes to 100 psi. I'll quote on old post of mine from another forum

Air pressure gauges are most accurate at 40 to 60% of the max reading (and still reasonably accurate out to the 25%/75% marks) so if you fill your tire to 24 to 36 psi a 60 psi gauge is appropriate. If you inflate to 38 psi or higher you'll want the 100 psi gauge (as the split between the two is the average of 36 and 40.). Many newer tires have a sidewall max of 51 psi (some still say 44 psi) and many hyper milers fill tires to sidewall or above. I wouldn't suggest that for the average driver but it's no less inaccurate than recommending one tire gauge for all uses.

Less importantly compact spare tires have a higher pressure requirement than a typical car tire (some as high as 80 psi) so it doesn't hurt to be able to accurately measure the spare.

Another factor is a tire pressurized to above the limit on your gauge can damage the gauge but an under inflated tire will give overly inaccurate readings on very high pressure gauges.

 

[dirkhh]

On a cooler evening if I have 42 the low tire pressure light comes on. I keep mine at 45.

I had my warning light come on repeatedly when filling to 42 at the gas station (at which point the tires are somewhat warm, I guess).
(btw: I enjoy driving to the gas station and getting change for a dollar bill so I can feed the air compressor with quarters)
So last time I filled to 45 and in the morning they still read 43psi and everyone is happy.