Tire pressure in winter months

I left Florida two weeks ago with 50psi, now 42psi in Maritime, Canada.

 

Boyles law, as I understand it, is based on a constant temp. We are talking about variable temp here of ambient cold vs warm with a consistent volume.

 

https://en.wikipedia.org/wiki/Charles's_law

Fair point, you are correct. You can derive the same information from the formulas.

 

Ok - this is cool and this making me reconsider my thoughts and approach.

 

Technically its https://en.wikipedia.org/wiki/Gay-Lussac's_law but they were all shown to be related by the https://en.wikipedia.org/wiki/Ideal_gas_law#Combined_gas_law
You get the picture.

 

I agree with all the comments on loss of pressure due to temperature change but I haven't seen anyone mention the idea that an extreme drop in temperature, say from 10 degree Fahrenheit to -20 degrees, will also cause the wheels to shrink and allow some air escape through a slight breech in the tire seal.

I had a 95 Subaru that lost tire pressure horribly with extreme drops in temperature. It did it with different tires over the years so I always assumed it had more to do with the rims since it hasn't happened to the same extent with any of my other vehicles.

Anyone? Bueller?

 

No need to be sorry, i totally understand your reasoning due to the temp swings you get. Like i said earlier, if it works for you, in the end that's all that really matters.

 

Thanks for referencing the correct limiting laws. I was getting surprisingly annoyed despite knowing this says more about me than anyone else.

 

I was thinking of the combined law when I posted Boyle knowing in my mind the laws are related. Brain fart on my end.

 

This is my experience with tire pressure for motorsport applications.

Ambient temperature 70°F tire tread temperature and wheel temperature 70°F air pressure 32.

Drove the car on the course for 1 minute. Tire pressure increases by 2psi (34) as the tire and wheels generate heat from the road course and brakes.

Set pressure back down to 32psi. Drove it on the course for a minute. Pressure increased by 2psi (34). Set pressure back down again.

Eventually, the tire pressure will plateau and you do not have to remove air anymore. But once the the tire and wheels cool down and back to the original temperature when you started. You pressure is now lesser.

The volume of air is going to be constant, but the pressure with increase/fluctuate along with temperature.

Now to the original question. What tire pressure to run in winter with snow/ice. There's different answers to that base on the weight of your vehicle and its occupants/load,, and type of tires you have. You want the tire to have maximum contact on the road. P metric all season will have different tire pressure requirements than an LT tire or Summer tires with 50 series vs. 75 series.

The answer is. Trial and error until you dial it in, in the current environment and roll with it. Tire pyrometer is a good tool to have if you really want to go in depth to it.

Also,, there is a tread here on how to calculate what tire pressure to run based on the tire manufacturer specifications and weight of your vehicle.

Personally, with my Cooper XLT, I will make it the softest I can when it's snowing and normal if it's just cold.

Now, I have to find tha tread again to get the formula.

 

Air bags will also experience shrinkage when the temperature dips.

 

Same with scrotum.

 

Heat something and it expands.
Cool something and it contracts.

 

My Hermetically Sealed Hand Chamber keeps a constant 72° for best anti-aging results. Argon gas inside is preferred.

 

so Nitrogen filled tires the benefits are 1.) it holds longer through temps fluxing. 2.) it gives a better feeling while driving. 3.) it can actually pro long the life of the tire and cause less tread wear.

 

Watch the Australian video posted high up in this thread.

 

4) Better MPG.

5) Longer oil change intervals.

 

6) Lower transmission towing temps

7) Increased payload