Winter Tire Pressure
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No you should never put extra air into a winter tire. Put the specified pressure for your car's set up that it says on the inside of your door. In winter if you fill your tire with the normal amount of air they will lose a small amount of pressure through the night, which is advantageous for when the car is cold as the tire provides extra grip. When you drive on the tires they warm up and return to the fill pressure. If you add extra air then they become over pressured when they warm up from driving.
When winter conditions are really bad you see people let a little extra air OUT of their tires if they get stuck because it maximizes the contact patch with the ground. You will never hear of drivers adding extra winter air as it diminishes the effectiveness of a winter tire.
tl;dr: just fill to the recommended pressure on your door sticker.
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Actually, filling tires with a bit extra air is recommended. In very cold weather tires can lose as much 5-6 psi overnight.
https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=168
https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=168
Yes this is actually correct. You should raise the tire pressure during the winter but makes sure to check the pressures when the car has not been driven and the temperature of the tire air is the same as the outside air temperature.
As quoted from the owners manual...
"If you equip your car with snow tires,
they should be the same size and
have the same load capacity as the
original tires. Snow tires should be
installed on all four wheels; otherwise, poor handling may result. Snow
tires should carry 4 psi (28 kPa)
more air pressure than the pressure
recommended for the standard tires
on the tire label on the driver’s side of
the center pillar, or up to the maximum pressure shown on the tire
sidewall, whichever is less."
Lower air pressure to increase the contact patch may help unstuck grandma's Buick in a snowbank but as for NOT being stuck and driving normally through the snow or even competitively, you will want a decrease the contact patch with higher air pressure. More pounds per square inch that is directed down on the tire siping and tread will increase traction during acceleration, braking and cornering.
So to answer Chris' question, Yes, around 38-40 pounds I run in the winter.
Coming from sand/buggy world; the interesting thing about tire pressure - The lower PSI would float more on the sand; higher PSI would dig, bounce and rut. Softer the sand; the more we would gas down the tries. 5-15 PSI was normal range (thus beadlocks).
I wonder if this applies to snow tires at all and how they interact. Also; is it better to dig/rut in snow or float on top... Eh, no idea; figured it might be interesting to play with.
That said; agreed with above, run on +4psi unless unless the rating for tire minimum is higher or measuring outside in cold. Some will have a inflation range like the blizzaks, others just max PSI.
I wonder if this applies to snow tires at all and how they interact. Also; is it better to dig/rut in snow or float on top... Eh, no idea; figured it might be interesting to play with.
That said; agreed with above, run on +4psi unless unless the rating for tire minimum is higher or measuring outside in cold. Some will have a inflation range like the blizzaks, others just max PSI.
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Now I assume that everything you are saying is true for normal winter driving conditions in the US. Where I live it hits about -20c and proceeds to fluctuate between there and -40c for the next 5 months. The roads are infrequently plowed outside the highway. For driving on more severe snow conditions on unplowed roads being underinflated will be helpful. It is like Zerobane was saying, you can float over the snow (in theory). Having harder tires is theoretically advantageous where your tires can dig down below the snow to hit asphalt, so this will be road condition dependent.
HOWEVER, I am NOT suggesting that you underinflate your tires because it's bad for your tires and wheels. I am suggesting that you fill the car to the recommended PSI. That means that when the tires heat up they will in fact be slightly over inflated. So you should be measuring the initial pressure from cold to assess how much to fill. Particularly, as the link sent by RedVN states: before driving, in the morning, after parking outdoors if possible. As the manual states in section 7-34, a warm tire will be about 4-6 PSI above the cold tire pressure. If you overfill by 4PSI when cold then you are in fact overfilling by 6-10 PSI when warm which will exceed the recommended maximum tire pressure.
Also the manual (at least my manual) does not state what you claim. It states that you can overfill by up to 3 PSI in the condition that the weather is expected to drop in the near future. That you can overfill by 1 PSI for every 7c(12f) that the temperature is expected to CHANGE. If you are filling cold tires and the temperature is expected to remain fairly constant then there is no reason to overinflate. I have attached the relevant sections of the manual you appear to be referencing, in case the misunderstanding is on my end.
Attachments
Or you could just check them regularly.
I do my best to get even tire wear. Run at the recommended pressures and if the temperature fluctuates significantly overnight (again, I live where it commonly reaches -20F actual temp) I just top them off in the morning if needed, and then when it warms up I let the air out if needed (after sitting overnight).
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