PSI drops by 1 with every 10 degree F decrease. Goes up by 1 with every 10 increase. With that in mind, no way should you ever have a 12 psi difference. I set my PSI a little higher in the winter (+3 psi), because in the garage, it is warmer, so the PSI is a bit too high vs. the outside temp, and some days are zero, others 50 degrees, so I set my PSI to the door jamb's pressure for 30 degrees for January, and then another 3 psi higher to cover me on the zero degree days.
One of the other problems with setting it too high is the surface area of the tire on the road will be less if the pressure is too high, reducing the safety of your car. And too low will also cause safety issues. Check PSI every other week .