Tire air pressure, something interesting or placebo effect?

[pho35]

So I'm on the quest to recalibrate the range estimation because my 2020 MY went down to 293mi @ 100% charge. I've been driving down to 20% and charge up to 100% a few times now and was able to "recover" to 295mi @ 100% this past week. However, I noticed something interesting that after I backed the car out from the garage, got the air pressure warning and pumped it to 39-40psi (20" induction wheels). Went back inside to summon the kiddos and went out noticing the range got bumped to 297mi @ 100%.

I thought it was interesting, anyone got the same experience?

 

[ScoobyDoo82]

So I'm on the quest to recalibrate the range estimation because my 2020 MY went down to 293mi @ 100% charge. I've been driving down to 20% and charge up to 100% a few times now and was able to "recover" to 295mi @ 100% this past week. However, I noticed something interesting that after I backed the car out from the garage, got the air pressure warning and pumped it to 39-40psi (20" induction wheels). Went back inside to summon the kiddos and went out noticing the range got bumped to 297mi @ 100%.

I thought it was interesting, anyone got the same experience?

Lol.. 2 miles gained has nothing to do with the tire pressure. In fact, the TPMS system is a joke. It’s hardly accurate enough for the car’s computer to actually factor the data in for range estimates.
For example, if you are unfortunate enough to have a tire with a slow leak (like me), you’ll truly get a taste of how wonky the TPMS is. It’s more of a “give or take 3or4 psi” rough idea of what your tires might be. A digital pressure gauge is always +/- by a few pounds when compared to what the car is displaying. The only way I can get all 4 to be exactly the same is if I use my portable Makita air compressor that has an automatic shutoff at a set PSI. I have it set to turn off at 42, so each tire gets exactly the same amount of air.
Placebo effect indeed.

 

[slink]

Lol.. 2 miles gained has nothing to do with the tire pressure. In fact, the TPMS system is a joke. It’s hardly accurate enough for the car’s computer to actually factor the data in for range estimates.
For example, if you are unfortunate enough to have a tire with a slow leak (like me), you’ll truly get a taste of how wonky the TPMS is. It’s more of a “give or take 3or4 psi” rough idea of what your tires might be. A digital pressure gauge is always +/- by a few pounds when compared to what the car is displaying. The only way I can get all 4 to be exactly the same is if I use my portable Makita air compressor that has an automatic shutoff at a set PSI. I have it set to turn off at 42, so each tire gets exactly the same amount of air.
Placebo effect indeed.

I also have a slow leak in one of my tires. Took it off could not find the leak. Took it to a shop they could not find a leak. Only have 7800 miles on the tires so I guess I am stuck with filling the tire every couple of days. What could be causing a leak that doesn't show up when submerged in water?
Interesting comment that the service manager said to me when I picked up the tire. "These tires should be inflated to 35 psi". I told him that is not what Elon wants and other 3 tires are holding air. He was surprised to hear that.
The TPMS system does seem to be joke. When I check the tire every couple of days it will be down to 37 psi. I thought the system was to alert the driver when the tire goes below 3psi under the recommended pressure. My TPMS light has yet to go off.

 

[Pianewman]

slink: Find another shop to do your tire work. Finding a leak isn't so hard. Service Manager advice re: tire pressure, considering the weight of the MY, could have led to some serious issues. Go somewhere else.
I'm not sure there is a TPMS system anywhere that would be as accurate as a hand-held pressure gauge. Mine reads high, but I can mentally adjust to it. It also quickly showed a pressure loss in one tire, found a nail in the shoulder, replaced the tire.

 

[jcanoe]

The recommended tire pressure is always posted on a manufacturer's label on the B pillar next to the driver's door. For the Tesla Model Y the recommended tire pressure is 42 PSI. Also, the OE tires on the Tesla Model Y have a load rating of extra load (XL). XL rated tires require either 41 or 42 PSI to be able to meet their load rating.

Any tire shop should be able to remove the wheel from the vehicle, then inflate the tire to 42 PSI, place the tire in a water tank to spot any air bubbles from a leak. One possibility is that the tire valve has a slow leak. If the cap in on the valve stem this might not show up using the water tank method.

Try this; inflate the tire to the recommended 42 PSI or even a few pounds over. Remove the valve stem cap and put a little bit of your spit (spittle?) on the end of exposed valve stem. If a bubble starts to form then that is the source of the air leak. The valve core can be unscrewed from the valve stem using a valve core removal tool and cleaned. Better yet just replace the valve core. (Note: This does not affect the TPMS.) You will need a tire inflator pump to reinflate the tire, else have the tire shop perform this simple repair.

 

[DanDi58]

The recommended tire pressure is always posted on a manufacturer's label on the B pillar next to the driver's door. For the Tesla Model Y the recommended tire pressure is 42 PSI. Also, the OE tires on the Tesla Model Y have a load rating of extra load (XL). XL rated tires require either 41 or 42 PSI to be able to meet their load rating.

Any tire shop should be able to remove the wheel from the vehicle, then inflate the tire to 42 PSI, place the tire in a water tank to spot any air bubbles from a leak. One possibility is that the tire valve has a slow leak. If the cap in on the valve stem this might not show up using the water tank method.

Try this; inflate the tire to the recommended 42 PSI or even a few pounds over. Remove the valve stem cap and put a little bit of your spit (spittle?) on the end of exposed valve stem. If a bubble starts to form then that is the source of the air leak. The valve core can be unscrewed from the valve stem using a valve core removal tool and cleaned. Better yet just replace the valve core. (Note: This does not affect the TPMS.) You will need a tire inflator pump to reinflate the tire, else have the tire shop perform this simple repair.

X2 on the valve cap leak - I had that on a previous car, drove me crazy. The valve cap kept me from finding the leak, but when I finally took it off and listened very closely I could hear it. Just enough leaked past the cap to turn on the TPMS every week or two.

 

[ATPMSD]

A couple of suggestions:
1. Always fill tires when they are cold, the stated fill pressure assumes cold tires
2, Always use a good quality pressure gauge
3. Always keep a 12v compression in the car. In most cases if you have a flat you can fill the tire and get to a tire shop. Not always possible of course.

 

[Darmie]

That number is just an estimate. There are many parameters that tesla uses to know mileage vs percentage. I wouldn't worry about the few numbers. If you start now, you won't enjoy the car. If you want to run some battery reports and such you can use teslafi but even then, it's just an estimate. Be honest with you, by leaving sentry off and not charging the car for 4 to 6 hours so the back can become one with the car computer is the best way to help calibrate but that's a 200 page discussion here on TMC somewhere. Bjorn videos is good knowledge too.

 

[dino007]

Yes i can add the tpms on the model Y is a guestimate it’s usually 2psi less off from what my handy digital gauge or compressor says when I’ve put air in

definitely not accurate compared to other cars I’ve had

 

[slink]

Thanks for the suggestions but because I didn't go into more detail in my original post they don't really apply. First I took the tire off on the car and took it to the shop. They couldn't check the b pillar. I also don't need a new shop, they have been inspecting my vehicles for over 20 years and they have always been straight up with me with any work they had to do. As a matter of fact the best service I have ever received on my cars. I also know how to find a leak. The only reason I took it to them was since I couldn't find one I thought they may be able to. Plus I trust them not to try to give a bs story about needing a new tire. I sprayed soapy water on the stem at least three times and got no bubbles. One thing I found today while rotating the tires, and I haven't noticed before, was the tire had a different cap on the stem then the other three. When I looked at the other three I could see what appears to be a gasket inside. I must of put the wrong one on in the past because I had the original one on a shelf in the garage. Although I can't see how it would be the cause since as I said I should have gotten bubbles with the soapy water if I had a leak out of the stem. Is it possible I lose air while the car is moving, hitting bumps and holes, and the gasket is there to stop it? Will see if that was the problem.

 

[jcanoe]

Sometimes a tire will just have a bad tire bead and never make a good seal with the wheel, else there is something that is preventing a good seal.

Unless the valve stem cap is somehow depressing the valve and releasing air I don't think this is the issue. (I did own at one time a set of valve stems extender caps that had a green pop up pressure indicator that would let you know when the tire needed air. (Crude but it worked. I don't believe you were describing one of the valve stems that provides a tire pressure check via a green popup.)

 

[slink]

At this point, if I keep losing air, a bad bead is the only thing it could be. With only 7900 miles on the tire I hate to replace it but I am also getting tired of bringing the pressure up every couple of days. Do you think I would have to replace both tires on the same axle or get away with only replacing the one?

 

[jcanoe]

Tire valve cores are like what $0.50? I would remove, clean and re-install the valve core or just replace the valve core to remove any possibility of the valve being the source of the leak.

You could have the tire shop dismount, clean the wheel mounting surface and remount the existing tire. That would be an inexpensive repair if that fixes the slow leak.

If you end up purchasing one new tire you might be able to have the shop shave the new tire so the tread depth matches the tire on the opposite side.

 

[Pianewman]

slink: I have OEM 19" ContiProContact. At 13k miles, very even wear on all 4, I picked up a nail as close to the sidewall as possible, actually vertically INTO the sidewall. Needless to say, not repairable.

So, close inspection showed wear between 6-7/32". OEM is 9/32". Visually, sipes were still quite sharp, shoulders looked virtually identical to the new tire.

TireRack said it was a close call, but recommended replacing both tires on that axle. The shop that installed my coilovers looked at them carefully, shrugged their shoulders, said just replace one tire. In their limited experience, Tesla differentials don't seem to be sensitive to such a small difference in diameter.

After a week of driving with only one new tire, with zero issues, my OCD got the better of me, and I replaced the opposite tire. I now have a 13k mile worn tire stored in my garage, awaiting a used 19" rim, to be used as a spare.

If your tires are evenly worn, at 7900 miles, I'd replace on the faulty tire, but, as usual, YMMV!!!!

 

[DanDi58]

slink: I have OEM 19" ContiProContact. At 13k miles, very even wear on all 4, I picked up a nail as close to the sidewall as possible, actually vertically INTO the sidewall. Needless to say, not repairable.

So, close inspection showed wear between 6-7/32". OEM is 9/32". Visually, sipes were still quite sharp, shoulders looked virtually identical to the new tire.

TireRack said it was a close call, but recommended replacing both tires on that axle. The shop that installed my coilovers looked at them carefully, shrugged their shoulders, said just replace one tire. In their limited experience, Tesla differentials don't seem to be sensitive to such a small difference in diameter.

After a week of driving with only one new tire, with zero issues, my OCD got the better of me, and I replaced the opposite tire. I now have a 13k mile worn tire stored in my garage, awaiting a used 19" rim, to be used as a spare.

If your tires are evenly worn, at 7900 miles, I'd replace on the faulty tire, but, as usual, YMMV!!!!

LOL, I wouldn't be able to go much longer replacing only 1 tire....! I always felt like you should do at least 2 (unless they are very new), even on my wife's FWD MINI Cooper in the rear.....

 

[slink]

Thanks to all

 

[tangible1]

The recommended tire pressure is always posted on a manufacturer's label on the B pillar next to the driver's door. For the Tesla Model Y the recommended tire pressure is 42 PSI. Also, the OE tires on the Tesla Model Y have a load rating of extra load (XL). XL rated tires require either 41 or 42 PSI to be able to meet their load rating.

Any tire shop should be able to remove the wheel from the vehicle, then inflate the tire to 42 PSI, place the tire in a water tank to spot any air bubbles from a leak. One possibility is that the tire valve has a slow leak. If the cap in on the valve stem this might not show up using the water tank method.

Try this; inflate the tire to the recommended 42 PSI or even a few pounds over. Remove the valve stem cap and put a little bit of your spit (spittle?) on the end of exposed valve stem. If a bubble starts to form then that is the source of the air leak. The valve core can be unscrewed from the valve stem using a valve core removal tool and cleaned. Better yet just replace the valve core. (Note: This does not affect the TPMS.) You will need a tire inflator pump to reinflate the tire, else have the tire shop perform this simple repair.

A slightly 'out of round' wheel (rim), or one with slight damage, can also be difficult to find a leak using the water tank method. I've experienced this on another vehicle.