Checking Tire Pressure

[Discoducky]

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

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

VIN3737, 60kWh and 45 is listed.

 

[neroden]

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.

Thanks for explaining the mystery. That makes perfect sense. :biggrin:

 

[Roamer]

Nitrogen Inflation

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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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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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.

Here are my 2cents on Nitrogen

I run nitrogen in all my tires. Added it up one day and had over 150 tires, many on collector limited use cars, so I bought a commercial Nitrogen machine.

NitrogenMan Nitrogen Tire Inflation

The nitrogen tires run cooler and hold a constant pressure better (I live in Arizona and pull car hauler trailers across the desert on hot days).

I installed Smart Tire systems on Several of my trucks, car hauler trailer and a Ford Excursion years ago. The system gives you tire temp, pressure and variance from set point based on an inflation curve that you set. Not sure if the system is still sold now that most cars come with a factory system.

I was stunned at the difference in tire temperature before I ran the nitrogen. With Nitrogen the tire temp never goes above about 130 degrees. Before Nitrogen I would see temps in the 175 range on a long drive at high speed across the desert. Same initial cold starting pressures.

I agree that for most users its probably not worth the cost and hassle to service with Nitrogen. But I don't agree that it doesn't effect tire performance and life.

My reason for going to nitrogen was consistent pressure on heavy duty loads and vehicles and the longer time periods for pressure loss.

The second reason is that on many of my collector cars the tires rot out rather than wear out. I have found with the dry Nitrogen my rims don't rust out on the inside and my tires don't dry rot crack on the outside. Again not problems for a daily driver that will wear out the tires before they rot out.

My recommendation would be that if you have access to nitrogen at a reasonable price you should use it.
Tires will hold set pressure longer.
The dry air is just better for everything.
Most important your tires will run at lower temps and stay at the desired inflation thru a wider range of temperatures and conditions.

It does work and make a difference but is probably not a big deal on daily drivers that check pressure regularly and wear the tires out in less than five years.

 

[Roamer]

Tire inflation

Inflate your tires to the number specified on the sticker on your door post.

Inflating your tires to the tire max inflation rating printed on the tire is not a good idea.

Your traction will be reduced and your cars handling will be effected.

The only time I would vary from the manufacturers recommended inflation would be a few pounds variation up or down based on the tires tread contact. If you always run light you may need a few pounds lower to get max tire wear and performance and if you always run heavy you may need a few pounds more.

Easy to tell if you look and the tire and see how much tread is contacting the road surface. A little dust on the tires and you can see exactly if you are getting complete contact across the entire tire surface.

All that said I would highly recommend you inflate to the manufacturer sticker on cold tires.

Every car dealer and service center I have ever worked with always way over inflate because they know most people never check their tires. They also know most people can't tell the handling difference so they just over inflate to compensate for less than diligent owners.

 

[Musterion]

Solution to 42 vs 45 psi on 19" wheels

Hi again with a followup to my post and some possible confusion. Note there are two stickers visible when you open the driver's side door (let's call them upper and lower). Upper sticker is more generic. Lower sticker pertains to your vehicle specifically and has its actual weight (depends on battery you have and gross weight determines the spec tire inflation) plus tire sizes installed. It also has date of manufacture and VIN number. This is the sticker you should be looking at. In any case the vast majority of posts (minus one, maybe due to wrong sticker quoted or wrong sticker applied?) are consistent with MS60's 19" wheel spec at 42 psi and MS85's 19" wheel spec at 45 psi. From my back-of-the-envelope calculation this is roughly what you would expect from the weight difference between MS60 and MS85.

 

[hans]

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.

People pay for air? I read somewhere that gas stations were required to provide air for free as a safety thing. I don't know if it's true or not (probably isn't) but for years now I have just confidently asked the clerk "can you turn on the air pump?". Many dozens of times doing this and I have never once had to pay for air.

 

[mknox]

People pay for air? I read somewhere that gas stations were required to provide air for free as a safety thing. I don't know if it's true or not (probably isn't) but for years now I have just confidently asked the clerk "can you turn on the air pump?". Many dozens of times doing this and I have never once had to pay for air.

California has a law requiring gas stations to provide air and water for free. (I saw this posted at a station while I was on vacation in July and in a rental ICE). No such law where I live and most stations charge for air.

 

[dirkhh]

California has a law requiring gas stations to provide air and water for free. (I saw this posted at a station while I was on vacation in July and in a rental ICE). No such law where I live and most stations charge for air.

Same here in Oregon (where you also have to have full service to fill gas (but strangely not for diesel which you can pump yourself).)

 

[Mayhemm]

California has a law requiring gas stations to provide air and water for free. (I saw this posted at a station while I was on vacation in July and in a rental ICE). No such law where I live and most stations charge for air.

Must be an Ontario thing. No gas station I've even been to out West has charged for air.

 

[SteveH]

Many stations in Texas charge for water and air.

 

[Mayhemm]

Huh. Maybe there's actually something good about living here...

Many stations in Texas charge for water and air.

That does not surprise me one bit.

 

[hans]

California has a law requiring gas stations to provide air and water for free. (I saw this posted at a station while I was on vacation in July and in a rental ICE). No such law where I live and most stations charge for air.

The funny thing is that many stations in California still try and charge for air. They have the machine that takes quarters like everywhere else. I suspect that the majority of people are unaware that they don't actually have to pay.

 

[PhilBa]

I don't know WA law but I've had to pay in the Seattle area.

Instead, why don't you just get a tire repair kit with a pump and do it at home. Cold inflation - no guessing and you have piece of mind if you get a flat.

By the way, I noticed my wh/mi creeping up a bit and checked my tires. Sure enough, I was running a bit low (40-42 on my p85). Proper inflation made a difference.

 

[hans]

I don't know WA law but I've had to pay in the Seattle area.

Instead, why don't you just get a tire repair kit with a pump and do it at home. Cold inflation - no guessing and you have piece of mind if you get a flat.

By the way, I noticed my wh/mi creeping up a bit and checked my tires. Sure enough, I was running a bit low (40-42 on my p85). Proper inflation made a difference.

I do this now. The Tesla tire repair kit has been handy and I always keep it in the trunk footwell.

 

[Musterion]

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.

I'd like to amend this post to mention that the 42 psi spec some are seeing on their label for 19" wheels might also be if you have coil suspension rather than air suspension. I noticed the alignment TSB from Tesla has different inflation specs depending on the suspension type. It is also possible that the correlation between 60kWh cars and the 42psi spec comes not because of weight but because of enhanced correlation between S60's delivered with coil suspension.

 

[dbw77]

I'd like to amend this post to mention that the 42 psi spec some are seeing on their label for 19" wheels might also be if you have coil suspension rather than air suspension. I noticed the alignment TSB from Tesla has different inflation specs depending on the suspension type. It is also possible that the correlation between 60kWh cars and the 42psi spec comes not because of weight but because of enhanced correlation between S60's delivered with coil suspension.

I just picked up my S 85 today, 21" wheels/tires, the spec says 42 psi.

On a slightly different topic:
When I picked up the car the Tire pressure warning came on, the DS looked at it, drove it in the parking lot and said it was ok.
Later when I got home, it came on again, I found all of the tires except one were about 35-36 psi, so I topped them off.
Apparently the factory delivery QA doesn't check the tire pressures before delivery.

 

[JPP]

I'd like to amend this post to mention that the 42 psi spec some are seeing on their label for 19" wheels might also be if you have coil suspension rather than air suspension. I noticed the alignment TSB from Tesla has different inflation specs depending on the suspension type. It is also possible that the correlation between 60kWh cars and the 42psi spec comes not because of weight but because of enhanced correlation between S60's delivered with coil suspension.

FWIW, my S85 with air and 19" Goodyears has the door jamb sticker listing 45 PSI all around.

 

[jerry33]

When I picked up the car the Tire pressure warning came on, the DS looked at it, drove it in the parking lot and said it was ok.
Later when I got home, it came on again, I found all of the tires except one were about 35-36 psi, so I topped them off.
Apparently the factory delivery QA doesn't check the tire pressures before delivery.

The only pressure gauge you can trust is your own--and that's only if it's a decent one. Never rely on anyone else's pressure gauge and always adjust your pressure the morning after anyone else has serviced your car. You just never know what odd things they might have done to the tire pressures. There are still people out there who believe that no car tire should be inflated past 30 psi! I hope those folks aren't working for Tesla, but tire misinformation takes many decades to die out.

 

[Gynob001]

My Model S indicated low tire pressure. Until now, I never learned how to inflate tires. Armed with a digital tire pressure gauge, I went looking for gas stations that had air outlets.
Lesson 1-Many had "out of service" or dysfunctional equipment.
Lesson 2-Not all gas stations have "Air" service.
Lesson 3-They charge an arm and a leg (for a first timer, it took a while to slowly increase pressure as I was worried about blowing up the tire). By the time I inflated the first tire, the time was up and the machine required another dollar! Overall, I spent four dollars to inflate the tires.
I had a nasty surprise when Model S showed 26-28 PSI (considering that the car was less than 2 months old). Is it common to lose about half the tire pressure in 2 months? I drive on nice, regular, even roads.
If it is common and routine, Am I better off buying an air compressor?

 

[strider]

The funny thing is that many stations in California still try and charge for air. They have the machine that takes quarters like everywhere else. I suspect that the majority of people are unaware that they don't actually have to pay.

Yep. I've gotten into arguments w/ a few station attendants over this. One of them I actually dragged outside to show them the sign that was posted on the side of their station stating that it was Cali law to provide it for free. They usually have a button they can push to activate the pump or sometimes they just give me a quarter.