So it was somewhere between 1 and 4 degrees this morning when I left for work, and as seems to happen throughout the cold months, my TPMS light came on. I double checked that I didn't have a flat and hit the road, driving to the closets gas station with a free air compressor. About a 5 minute, mostly highway, drive. The door jam of my car says my tires should be at 33psi. They were all reading about 29 (sigh of relief as at least they were consistent so I knew I didn't have a leak). I fought through the pain of holding a metal air gun in 4 degree temperatures and added air. It was taking a while and it was getting pretty painful so I only filled each to about 31psi, enough to turn the TPMS light off.
So, question. I get tires expand as you drive and they heat up, and I get that the bitter cold shrinks them and thats why they loose air. So should I have filled them to 33 as recommended? or was 31 fine because its so cold and they'll expand a bit?