Checking Tire Pressure

[astrotoy]

I've been spoiled with my Lexus LS460L - it has tire pressure sensors which tell you what the pressure is on each tire. The Tesla S doesn't do that. So do you rely on getting a warning signal (I never have gotten one) that a tire is low before you check the pressure, or do you actually measure the tire pressure at some regular interval (like when you fill up at the gas station . So far the only time when my tire pressure has been adjusted has been at the Tesla Service Center.
What do you do? Thanks.

 

[jerry33]

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.

 

[texex91]

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

Oh, I like that--next release after 5.0? Gotta love software release updates!

 

[caddieo]

What do you do? Thanks.

For the past 30 years, I have always had a small AC-powered air compressor capable of 100 psi (my latest one is from Sears) in my garage and identical tire pressure gauges in the garage tool box and for any car going on a long trip. I check tire pressures on all cars every 2-3 weeks as well as before trips of over 200 miles. No different with the P85. I frankly do not trust the accuracy of tire pressure readings in public tire inflation stations.

 

[astrotoy]

Thanks for the help.

 

[gmontem]

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.

Cool thanks. I'm very confused between a ball chuck and an angle chuck (Longacre 50406 vs 50408). Does either work with the Model S tires?

 

[apacheguy]

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

Not even going to ask how you know that, but sweet!

 

[jerry33]

Cool thanks. I'm very confused between a ball chuck and an angle chuck (Longacre 50406 vs 50408). Does either work with the Model S tires?

Either will work. The main difference between the two gauges is that one is just a gauge and the other attaches to an air compressor hose so you can inflate and adjust easily. I replaced the hose and chuck on mine (50406) with a clip-on chuck and longer hose.

 

[hoopty_yo]

There's no TPMS on the Model S? How did they get around that? Looky here:

In the United States, the United States Department Of Transportation (NHTSA) released the FMVSS No. 138, which requires an installation of a Tire Pressure Monitoring System to all new passenger cars, multipurpose passenger vehicles, trucks, and buses that have a gross vehicle weight rating (GVWR) of 4,536*kg (10,000*lbs.) or less, except those vehicles with dual wheels on an axle, as of 2007. In the European Union, starting November 1, 2012, all new models of passenger cars must be equipped with a TPMS, with even tighter specifications that will be defined by the UNECE Vehicle Regulations (Regulation No. 64). From November 1, 2014, all new passenger cars sold in the European Union must be equipped with TPMS.*

 

[jerry33]

Not even going to ask how you know that, but sweet!

IIRC, that was in the TESLIVE video.

 

[JPP]

hoopty-yo: there is a TPMS, just no digital display of the readings. The data is there, just not available to us now.

 

[hoopty_yo]

Thanks, good to know, but I thought the point of the system was to alert the driver of a possible safety issue.

 

[JPP]

It is---if your tire pressure is low, you will get an alert, Just no specifics on which tire, how much and how bad. Stay tuned.....

 

[Cosmacelf]

Actually, it triggers way before the tire is dangerously low. I've got a slow leak in one of my tires, so I get a notification about once a week. The tires are supposed to be inflated to 45 psi, and it triggers when they fall to about 38 psi (19" tires), which is about 15%. It will be nice when the TPMS tells you what the PSI is and which tire it is that is low!

 

[jerry33]

Actually, it triggers way before the tire is dangerously low. I've got a slow leak in one of my tires, so I get a notification about once a week. The tires are supposed to be inflated to 45 psi, and it triggers when they fall to about 38 psi (19" tires), which is about 15%.

That is dangerously low in my opinion. I want to know when it's 2-3 psi low to prevent further damage to the tire.

 

[solar powered]

Cosmacelf:
jerry33 is very knowledgeable source and I do concur that waiting for the TPMS monitor is way too low to prevent damage to your tire. I did something similar with my first car and the blocks on my tires developed a sawtooth pattern that created a racket. Only way to resolve that was to get new tires.
I keep my front tires at the recommended pressure, but increase the left front about 1 psi more (tighter cornering on right turns). I keep my rear tires 1/2 psi lower than recommended because I believe that it would lessen the inside wear due to the negative camber. Anyone else doing something similar?
Cosmacelf, I take it that you have 19" wheels, since you mention 45 psi. The owner's manual says that the 245/45-19s should be inflated to 45 psi (also confirmed by Walter Franck at Tesla), but the label on my driver's door sill says only 42 psi. I was wondering whether any other 19" wheel owners had the same conflicting info?
All of my preceding pressures are based on the assumption that 42 psi is the correct inflation pressure.

 

[dsmith2189]

Cosmacelf:
jerry33 is very knowledgeable source and I do concur that waiting for the TPMS monitor is way too low to prevent damage to your tire. I did something similar with my first car and the blocks on my tires developed a sawtooth pattern that created a racket. Only way to resolve that was to get new tires.
I keep my front tires at the recommended pressure, but increase the left front about 1 psi more (tighter cornering on right turns). I keep my rear tires 1/2 psi lower than recommended because I believe that it would lessen the inside wear due to the negative camber. Anyone else doing something similar?
Cosmacelf, I take it that you have 19" wheels, since you mention 45 psi. The owner's manual says that the 245/45-19s should be inflated to 45 psi (also confirmed by Walter Franck at Tesla), but the label on my driver's door sill says only 42 psi. I was wondering whether any other 19" wheel owners had the same conflicting info?
All of my preceding pressures are based on the assumption that 42 psi is the correct inflation pressure.

SolarPowered, I think that the 42psi door label is for the recommended inflation. the 45psi is the maximum cold psi for the tire. on my last car I kept the psi at the max pressure marked on the tire.
I received a low pressure warning on my MS last week because of a screw I picked up on the H1. I am glad to hear that they will be displaying the pressures for each tire in an upcoming update.
I have a quality digital gauge that I could have used but wasn't aware of the low pressure until I was already on the road. to me this is a safety concern and needs to be fixed ASAP. I would have been able to make an informed decision if I had known what the exact psi of the bad tire was. if it was too low I could have pulled over immediately and waited for roadside assistance. if it was only 1psi low I would have called from my destination (what I actually did) With 21" rims there is little room for loss of pressure.

 

[Cosmacelf]

Actually my door label just says 45 psi cold tire pressure. Nothing about max. Pressure. And yes, 19" tires.

 

[Mayhemm]

SolarPowered, I think that the 42psi door label is for the recommended inflation. the 45psi is the maximum cold psi for the tire. on my last car I kept the psi at the max pressure marked on the tire.

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.

 

[dsmith2189]

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.

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.