Temp Inversion and Tires?

[LAF]

So guys with tire monitors how do you handle this or what do you do.

Since the install of the Doran and cool weather in the mornings and 80 in the days I am warned in the mornings at 5:45 AM they are low. Which they are, 40 front and 46 rear. Of course a few miles all is well due to getting them warm. Get on it at 3:00 PM they are dead on.

So since they are in fact low in the morning indicates to me that tire pressure goes down when temps go down. I would assume colder air is denser as it hold more oxygen then warm air? For some reason I don't remember the reason for this and probably should.

At any rate I am having fun with the Doran and it does make you aware of tire pressure fluctuations as I wanted. I can then proof out tire pressure is not why my tires feather, if they decide to at an early mileage.

Ohh while I am crazy about tire pressure, I don't worry about 40 and 46 for a few miles in the morning, but I am very curious what happens all winter.

[jzeiler]

Does the Doran not temperature compensate? The smart tire shows a cold of 48, then as the tire heats up it reports a delta pressure (which is 0 or -1 +1 if there is a change in static pressure. Then it reports the tire temp. Mine routinely shows a -1 or -2 delta with an absolute of 53 until the temp reaches around 130 to 160 then it reports a delta of 0.

All Gases, i. e. air, contract and expand with temperature. If you set tire pressure at 30 degrees and it warms up to 70, you will see an increase in pressure. That is why a delta read out helps you adjust the warm pressure (from riding if necessary) if it is out of limits. Say you start out at 48 in the morning at 30 degrees but the day wears on to 70 degrees, a delta of +4 would let you know that the actual 57 psi should be dropped by 4 pounds to bring it back to an equivalent 48 psi cold setting.

[LAF]

No delta on the Doran.

Thank you for the explanation.

I would like that feature but can live with out it too. Although on a hot fill it would be super. I pretty much see a steady 56-57 rear and 47-48 front running 70-80 on slab. So if I saw a bigger number then that I would know that I am low hot and would go 2-3 pounds or so and see how it acted, you can always let air out ;)

I just found it curious and wondered if others see it also. I just get to set a threshold of 12.5% so I set it to go off at 40 and 46 as I said I want to proof out these Avon Storms, particularly the front. Little over 4000 and they look new and feeling them with your hand and still no feather.

[XMagnaRider]

So guys with tire monitors how do you handle this or what do you do.

Since the install of the Doran and cool weather in the mornings and 80 in the days I am warned in the mornings at 5:45 AM they are low. Which they are, 40 front and 46 rear. Of course a few miles all is well due to getting them warm. Get on it at 3:00 PM they are dead on.

So since they are in fact low in the morning indicates to me that tire pressure goes down when temps go down. I would assume colder air is denser as it hold more oxygen then warm air? For some reason I don't remember the reason for this and probably should.

At any rate I am having fun with the Doran and it does make you aware of tire pressure fluctuations as I wanted. I can then proof out tire pressure is not why my tires feather, if they decide to at an early mileage.

Ohh while I am crazy about tire pressure, I don't worry about 40 and 46 for a few miles in the morning, but I am very curious what happens all winter.
I have the factory-installed TPMs in a 2007 GT.

They are supposed to be temperature compensated, but I have observed that the readings increase 1-2 psi as the tires warm up.

I haven't noticed any difference in TPM readings based on the ambient air temperature. It is not uncommon to have a 30 degree difference in ambient air temperature between the early morning and late afternoon commutes.

Pressure changes with temperature. An external gauge will give increasing tire pressure readings as the air and tire temperatures increase. That's why it is important to be consistent about external gauge readings. Published tire pressure recommendations are for "cold" (not ridden yet) tires.

[Stixx]

In cars a sudden drop of temperature will cause a loss of tire pressure but once compesated it rarely repeats. i.e. First freeze check you tires and they could well be five psi off. Top them off while cold and run them for a week and you should see little or not change unless the temperature relly plummeted dreamatically.

I don't know the science of it just the reality. Beem topping my cars now bike off for years . Rarely need to repeat it. Just check them and replace what you lose while checking them.