tubi

How do you setup your tire pressure for winter weather condition when ambient temperature can vary by as much as 30F during the day? Inflate the tires by an extra 3psi so they will never go below the recommended pressure during the coldest part of the day?

equ

I'm curious about this as well. I don't think there is any hard and fast rule...

I've been using 35f/33r on the stock 245/40-18's (recommended 32/29 low load, 33/35 high load). My snow tires are 225/50-17, so the recommendations change slightly (33/30 low load and 35/36 high load). It seems that narrower tread and higher sidewall imply slightly higher pressures. That and the colder temperatures that the car will experience compared to the garage it is parked in (about 40F on a 25F day), I put in 37f/35r. So far I haven't had them on snow so YMMV.

Even at 36f/34r, the 225/50-17 michelin pilot alpin pa3's had great feel and handling, arguably better than the pirelli p7's.

kleinbus

Depending the variation, just set the pressure at normal temperatures as tire and air inside warms up a bit during the drive and increases the pressure back to normal. So your car may give you TPMS warning after cold night but it goes away after driving a while. Though you need to do visual check on all tires when you approach the car so you know TPMS warning is just about a bit lower pressure and not about flat tire.

Optimum would be to set the pressure at middle of temperature variation. Though when you drive needs attention too.

For example, if day is +40F and night is 0F, middle is +20F to set desired pressure.

To make this a bit more complicated lets focus to few other things, for example if you drive 95% of drives at night then 0F would be right temp to set pressure and day time it would have a bit overpressure but who cares a you barely drive daytime.

Now we can throw previous crap to trash as when I grew up at Arctic Circle levels, with cars and 18-wheelers and charter busses I got involved, the pressure was set to desired at ambient temperature no matter it might been 0F and forecast was showing -20F for the rest of the week.

There is physics equations for gas compression / expansion per volume and temperature, I will see if I can find it to compare passenger car inflation volume to truck tires.

equ

On the MY2010 that I have, you can reset the TPMS to what you like... I think it will allow for a lower rear.

Also, it warmed up a touch today, I'd like to report back that 37f/35r is a touch too much for an unloaded car, I may ease them down a bit if it looks like it's going to get warmer still.

kleinbus

Yep I forgot it records each wheel. When I swapped from summer to winter, I got tpms warning so I pressed "record pressure" and warning went away.

Anyways, I erased that part from my previous...