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So I have an accurate digital air pressure gauge and set all four tires to 41 PSI. When I refresh the My Chevy App it shows two tires at 41, one at 40 and one at 39. Not surprised with the 40 PSI reading but kinda am with the 39 PSI reading. Anyone else experience similar?

Craig
 

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So I have an accurate digital air pressure gauge and set all four tires to 41 PSI. When I refresh the My Chevy App it shows two tires at 41, one at 40 and one at 39. Not surprised with the 40 PSI reading but kinda am with the 39 PSI reading. Anyone else experience similar?

Craig
Wait awhile. The TPMS will reset. Also, they are not perfectly accurate. Like all instruments, they have a tolerance.
 

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Yeah, TPMS is there to warn of significantly low tire pressure, not as a substitute for a tire gauge. The resolution is pretty low, and I wouldn't count on the accuracy beyond a certain point.
 

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Mine are overall close, but depending on a day and pressure (ambient temp and driving style) they will be off by 2 psi. I would not worry about it.
 
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Even the manual says:

Tire Pressure : Shows the approximate pressures of all four tires. (My emphasis)
 

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When I inflate my Bolt EV tires to the same pressure according to the external gauge, the TPMS readings vary by 8 kPa (1.16 psi) in the extreme case. The resolution is 4 kPa, so that's just two steps. I can see how those with psi reading can vary by 2.
 

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Never had a car with TPMS before. It is fascinating to see the pressures change as the tires warm up, and how parking in the sun can have the sunny side higher than the shaded side when you come back to the car.
 

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Never had a car with TPMS before. It is fascinating to see the pressures change as the tires warm up, and how parking in the sun can have the sunny side higher than the shaded side when you come back to the car.
Even a DCFC charging session can warm up the front tires and make the pressure rise. I had to adjust accordingly while replenishing air in the tires with the car plugged in.
 

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I use thermal imaging camera for finding best tire pressure when playing with custom build or different type of tires..... you got to have knowledge on car alignment and how alignment affects temperature across the thread width.... Factory specifications are always designed with smooth ride and sacrificing efficiency up to certain level... but gaining more traction for emergency braking was the biggest contributor because of low rolling resistance tires and being set at 38 PSI Factory...
I have found sweet spot on bolt with Factory michelin tires winter 42 PSI and summer 40 PSI...
Some will like some will not.... try for yourself.....
My experience could not be the same how you or anyone else would feel...
It definitely helps with W/MPH consumption..
It does better than BMW I3 Rex at 55 MPH
 

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I've read that tire pressure will change 1 PSI for 10 degrees F temperature change. Found that to be right on. Naturally, checks need to be made with cold tires, sitting for several hours, and in the shade.
 

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I've read that tire pressure will change 1 PSI for 10 degrees F temperature change. Found that to be right on. Naturally, checks need to be made with cold tires, sitting for several hours, and in the shade.
As suggested here and by GJETSON, pressure will vary considerably (2-3 psi) if one tire is in shade and one in sun. I even get variation from one side of the car to the other when not in direct sunlight..
 

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Is that cold, or warmed up?
Cold.... You will notice that my pressure for winter (snow) is higher than summer.... but after couple days going from 36-42 I found with my style 42 for winter with stock michelin to be just right.... it gives me more feel when they loose traction.... what for someone who looks for absolute max traction 36 would be better but then efficiency is getting worse...
But I'm getting new set of Michelin X ice for winter tomorrow.. I just don't want to make my girlfriend feel scared in the snow and ice...
I have no problems 90% of time using stock tires in the winter .. but looking from safety side Winter tires are great investment.
 

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As suggested here and by GJETSON, pressure will vary considerably (2-3 psi) if one tire is in shade and one in sun. I even get variation from one side of the car to the other when not in direct sunlight..
Heat pressure has affect when you towing close to the tire limits or loaded up to the limit tire capacity.... but for normal driving 2-4 PSI is not something you should be worried..... There are good research from Michelin on tires and how pressure .... load.... side wall..... thread design.....alignment.....and many other things affect rolling resistance tire life and etc.
 
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