That will come normally as the air will contract as it gets colder, but do check to make sure they are even and don't become too low. I just checked my tires, which were at 25 psi in -15 celsius, and I normally keep them at 32 psi. It will only get colder here this time of year, so I filled them up to 31 psi.But I've heard it's better to have lower pressure in winter to give better traction in snow.
I'm aware Max PSI on this is 50 so I'm well within operating range.Just remember what I said - 35 on cold tires is 40 on hot tires.
Kinda off topic but...I remember reading somewhere that the largest amount of punctures are caused by underinflation (apart from glass, nails, curbs etc...). Any truth to that? Which is worse - under or over inflation?
Both are pretty bad,I'd say under is worse because you don't want extremely soft sidewalls that the rim will just roll over under cornering... it wouldn't be pretty in an extreme situation. Unless you overinflate to the very maximum a tire will take... then that's probably worse.