Cold tire pressure
 

I noticed that my tires are at 36 LBS in the morning but after they warm up on my drive to work, they show 41 LBS.
What pressures do you guys see in the morning, compared to after a day of driving. I know I should be at 33 LBS at start up.

Thanks

MICHELIN PRIMACY MXM4 19" 33 cold 35 hot.

on the side of the driver's door it says set the pressures at 33, and that would be when the tires are cold like in the morning

heat from the road and outside air raises the tire pressures, this is correct and anticipated to happen when setting them to 33

33 gives a nice soft ride, note that your manual says to set the psi higher when driving at higher speeds on the highway

note that there can be difference between a hand gauge and the TPMS display depending on what altitude you are at

for example I live at 6000 feet altitude, so my hand gauge reads about 4 psi higher than my TPMS dash display

this is because the TPMS things on the rims are calibrated at sea level and there is a difference between relative and atmospheric air pressure

personally I feel 33 is too soft and makes my tires wear faster in the middle, I set mine at 37 psi hand gauge, everybody seems to differ a little on this

I'm running 19" P7's. Thanks for your informative post.

I run mine at 31 cold

I run mine around 37 cold as well.
Bridgetone Turanza Serenity.

How much pressure do you see after they heat up?

It will usually get to 38/39 depending on temps/roads/driving. I'm not sure on the accuracy of these sensors as they tend to waver a bit on my car, but generally seem to stay within a pound or three.

Tire sidewall and tread flex at the contact patch is responsible for most of the heating. The Ideal Gas Law equation is PV=nRT, so Pressure is dependent on nRT/V. Since n is the number of moles of gas in the tire and is constant, and R (ideal gas constant) and V (the volume inside the tire) are also constant, essentially Pressure is directly proportional to Temperature.

33/34 cold. Gets up to 36/37 when hot.

Thanks Guys !!!! Now, I have a better view of my options. This group is the ****.:D:D:D

35 cold 37 hot with outside temps around 65 degrees.

I'm not sure about all this. I'm in the Bay Area so where I park, it's prob 10ft higher than the Bay water. My car reading is consistently higher than my hand hell. It's normally 2-3psi higher in the car.
I just chalk it up to imprecision of the sensors. At least they are consistent to each other which I care about. As of late I've been paranoid since my old set of tires were wearing unevenly & I want my new set to last as long as possible after realignment. Interestingly, it was just toe that was out.

I set thru a machine all my tires to 32(didn’t do spare). The car’s sensors measure them: three 33, one 29, spare 45.

Mxm4 33 cold