Tire pressure settings with heated garage in winter

Assuming my heated garage is 60F, and winter is coming with very cold temps, assuming 1psi drop for every 10 degrees in temp drop, should I set my 60F �cold� tire temps a few degrees above my target (goal) pressures? How much does the tire pressure drop when driving out in the cold when it�s, let�s say, 20F outside coming out of a 60F garage?

Yes. Set about 4 psi higher than your garage reading assuming you'll see on average a 40 degree temperature gradient.

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PSI spec assumes 68 degrees ambient temp & concrete floors really hold the cold which causes flat spots in the tires. I would over inflate by 5psi initially & lower after driving if needed.

Doesn't matter until Spring. ;-)

Matters a whole bunch if a tire sits flat for months at a time especially if you can't air it up on site.

If you move to the South, you can drive 12 months of the year. Just be sure your a/c works!

sorry about the duplicate!

Just roll it around every couple of weeks. That's going to help more than pressure. Flat spots suck... and your engine seals will love you for it.

I think people are missing the essence of Mike's question. He's not storing the car. He wants to know what pressure to set the tires, when in the garage, so they are not significantly underfilled when he's out in 20 degree winter conditions. At least that's how read it and responded.

You could just park it out in the cold for a while check the psi then adjust accordingly.

I would have said yes raise it a few psi over spec, but then the Porsche TSB exists to confuse me:

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Correct. It�s a bit like the inverse of how tire temps can increase dramatically in the racetrack, so setting the proper temperature beforehand is where it�s at. I didn�t have this problem until I had a heated garage. Im also curious how much tire temperatures might increase for those parking outside and then driving on the road. I�d suspect the cooling effect of regular street driving is way more of a impact on temps than any friction on the street.

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According to the above, it appears we can still have increased pressures, not lower pressures than 36/36 or 36/44. My car has 18�s and I�ve always had good luck with stock 36/44. I might inflate to 40/48 and then do some testing to see what real temps are and post back, my temps, temps after driving in the cold, etc.

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I just think it is strange that the tire pressure is specified at 68F, not at whatever the current ambient temp is.

Using a air dryer on your air source makes a huge difference,, any moisture in the tire increases the pressure swings. Can always run Nitrogen it does not expand and contract as much as pure air. And the gas from the tank is water free. (I find the dryer gives me sufficient benefit vs a Nitrogen fill YMMV)

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Maybe that�s where they set the bar (no pun intended)? Maybe pressures can be lower as temp decreases?

I'm a bit **** retentive when it comes to tire pressures. I check them periodically with the car outside for an extended period of time in winter, like after work.

The first part is very true. The second part is false. Remember PV = nRT It just so happens that most nitrogen filling systems are better maintained, yielding a dryer air vs ambient.

OOPs I should have said compressed raw air..

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According to Wiki for my curiosity, PV = nRT where , and are the pressure , volume and temperature ; is the number of moles of gas ; and is the ideal gas constant . It is the same for all gases.

Noooooooooooooo Math!

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I think you meant that pure air has no moisture in it, which help help with consistency.

Nope he was correct, that's what airplane tires have to have.

Airplane tires are not filled with pure air. And while we're here, cold floor don't cause flat spots.

Likely hood of flat spots is directly related to tire construction, My daily is a lifted jeep with larger traction tires, you definitely get flat spots when parked,, temp doesn't seem to matter. A month or two parked really does it, but they usually go away with a few miles to warm up.

So I�m running +4 front and rear, and felt like they were overinflated today with 40F temps. A little slippery. Granted, it was wet out. Tomorrow will be 20F, so we shall see the difference. I�ll take pressure reading after driving back an hour in 20F temps.

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Correct. However, the nitrogen is used because it does not expand and contract with temperature. Just think of a 200psi tire on a hot day in Houston say 84 degrees like today. Fly 9 hours to London at -49 degrees F. Then try to land in London at 34 degrees. The tires would be so low on compressed atmospheric air it would be unsafe. Nitrogen allows the tires to remain at the recommended pressure of 200 psi.

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Not true! Nitrogen absolutely expands and contracts with temperature change. https://www.engineeringtoolbox.com/nitrogen-d_1421.html As far as how an airplane tire holds up with temperature change, they use pure nitrogen because regular air would have moisture in it that would turn into ice at freezing temps and that could be unsafe. Or turn into steam at high temps, causing a blowout.

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I will agree and disagree: Aircraft tires are usually inflated with nitrogen to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight. [5] Dry nitrogen expands at the same rate as other dry atmospheric gases (normal air is about 80% nitrogen), but common compressed air sources may contain moisture, which increases the expansion rate with temperature. [6] The requirement that an inert gas, such as nitrogen, be used instead of air for inflation of tires on certain transport category airplanes was prompted by at least three cases in which the oxygen in air-filled tires combined with volatile gases given off by a severely overheated tire and exploded upon reaching autoignition temperature . The use of an inert gas for tire inflation will eliminate the possibility of a tire explosion. [7]

I think you guys are over thinking this. Do what Hacker wrote and check your tire outside and be done with it.

Two things. Junior year of college we were taught that there no such thing as an ideal gas. I was very disappointed but learned that PV=nRT is okay for estimation. Two, air is ~80% nitrogen. My understanding is that nitrogen is used in airplane tires because it does not support combustion.

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It certainly helps, in my experience of maintaining a fleet of 100 new press review vehicles. Rolls Royce owners manuals state to inflate their tires to 50 psi when stored. The colder the floor the colder the tire.

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The tire pressures were the same (+4psi) after driving an hour in 20F temps. I set +4psi at 55F. So either there is some buildup of heat while driving (mostly expressway at 70mph), or there isn�t enough of a pressure difference to matter much. Or my gauge is not very precise. EDIT: actually, I think the pressures went up 1psi at 20F after HWY driving versus 55F cold.

I inflate my winter tires to 40 psi on all four wheels as that seems to be psi where the tires handle the best. This morning it was -9F and it will get to 0F here today and they run fine at this pressure.

Going to be an awfully stiff ride & probably reducing contact patch.

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After checking the forecast, I added 2psi to the tires on my wife's Turbo S (beetle) this morning I see you are in SoCal. You do realize we are talking about driving with really, really soft rubber with a high level of silicone and slices cut into the thread in sub zero temperatures? There are days when even driving hundreds of miles the tires do not heat up much at all. For those who are really, really **** retentive...keep a log in the summer and check pressure when you leave and when you arrive while also logging the ambient temps when you were checking. Then keep checking your tire pressure after driving in winter, see what kind of driving and ambient temps it takes to reach the same "hot" pressure in winter. On top of that, in my experience winter tires just too mushy at the same PSI per all above conditions as summer tires, so I tend to run them a bit higher. To add to the confusion, some say higher PSI will give better snow traction as the tires can "dig in" better. Side note.....parking my Yukon outside and checking the tires at sunset, one side can be 2psi higher than the other side compared to checking them at high noon

Sounds like its time for an aftermarket TPMS

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At these temps everything is stiff 😜