I'm curious what tire pressure is more recommended for the Mazda6 2015 Touring? I recently bought one used and I got each tire to 35 PSI however I also just go a tire pressure warning. After some research, the tire-pressure warning could also be a "reminder to check" as described here.

But it made me realize, the recommendation on the door is 35 PSI but I know the recommendation varies depending on temperature and environment. I live in San Diego, CA and drive mostly on the highways. Is 35 PSI most optimal? How about filling with Nitrogen?

 

A few comments in no particular order:

• Air is something like 87% nitrogen as it is; paying someone to up that to roughly 97% nitrogen (you'll never reach 100% unless the tire is mounted in a 100% nitrogen filled tank) is a waste of money.
• The 35 psi recommendation doesn't change regardless of the OAT; said another way, regardless of whether the OAT is twenty below zero or over one-hundred degrees above, the target psi is still going to be 35.