The listed tire pressure on the door frame is the cold air tire pressure.

 

The tire will heat up or cool down due to road friction and ambient temp. Basically for every 10 degrees change in temperature the PSI of a tire can change +/- 1 PSI. For example, if the tire is filled cold to 32PSI @ 60F and the internal temperature of the air inside rises to 90F the PSI will rise +3 PSI = 35 PSI. The same in reverse, if filled 35@ 90F and the temperature drops to 60F = -3 PSI = 35 PSI.

In summary:

1. A higher PSI will have lower tire resistance and better MPG, but a harsher ride.
2. The lower PSI there will have a greater tire resistance, lower MPG but a slower ride.

IMHO on our 7th gen anything between 30-40PSI should be ok. It's just: pick a poison.

Note: Nitrogen fills tend to vary much less with changes in temp.

 

Also worth noting at this time of year, a higher PSI will have better rain and snow traction.

 

Hmmmm....that seems counter-intuitive, as you are lessening the contact patch. Wouldn't you lower the pressure a bit instead?

In any event, looking at the manual for my 2022 (on page 251 of the electronic version) under Driving Tips there is this warning: "Maintain the recommended level of air pressure."

 

You're right, to the extent that you should not go ABOVE the recommended pressure. But when left alone, tire pressure that starts at the recommended level and is then neglected will of course trend downward; there's little danger it would drift upward (unless you filled it just before an extreme summer heat wave).

To your counter-intuitive comment, you might think the size of the contact patch was the biggest factor, but I recall seeing some research that what governs instead is that an underinflated tire pinches the contact patch's tread grooves, lessening the channels that manage ice and snow. So, underinflation is the real enemy in the slop.

 

I'm at 35-36 psi cold depending on temps in the morning, and it goes up to 38-39 psi with 30 min driving, even higher on a long trip, I've seen 42 psi from 35 cold, definitely notice the rougher ride when psi gets that high.
Last time my pressures dropped to 33 psi cold I got a low pressure warning on the dash, the car felt too mushy anyway, plus I would be worried about damaging the wheel rim, terrible roads here, the car handles better with some air in the tires, but too much and ride goes out the window, the recommended cold psi is spot on taking into consideration all the factors for me, but it helps that generally my drives are short and psi stays below 40.

I know people don't rate nitrogen, but really if you don't want your tire pressure to fluctuate much then that is the solution.

 

LOL. For the $500 my local dealer wanted to charge me for it, I can keep checking and adjusting as needed.

 

Hate to split hairs but the nearest gas station to me with air machine is a good 10-12 minute ride and I assume the tires and the air in them are already warmed up by the time I get there.. So is putting air in those (not cold) tires still considered to be the tire pressure I dial up "cold?"

 

Needs to be done cold even before sun shines on 1 side of car as that changes pressure in tire. Buy a cheap 12 volt air compressor is a simple way to do this at home.

 

Add 3 or 4 psi to compensate for the drive. Shoot for 38-39 psi. Or splurge for a $30 tire inflator from Amazon.

 

Or just do a trial - measure before you leave home and again once you reach the air...the increase will show you how you need to adjust.

 

delete me...

 

That sounds like a plan, as the Sharper Image compressor I have in the trunk is okay but takes a long time.

 

The 12v air compressors take a long time to inflate a tire for the same reason a 4 cyl engine takes a while to get you to 60 mph.
I gave up on that years ago, and bought an AC compressor (120v, so I guess it's about 10 times better) and an air hose long enough to reach all 4 tires. I forget the brand, but you don't need a really big one, and there a bunch of them out there for less than $100.00.
Your friends will be stopping over all the time for free air once they find out there is no coin slot on the compressor.

 

Ok so you do have an air source at home but choose not to use so try this. Measure cold and if 32 and want 35 fill 4 psi over what ever reading is at air station and then next morning deflate to 35 psi.