I have read many of the comments re tire pressure loss but don't know if I have a unique problem or not. I own a 2011 GMC Terrain and my tire pressure is monitored through On Star. Every report I receive tells me my pressure is low in all tires - about the same amount, with little variance. Fortunately I own a air compressor and add air - virtually every 10 days or so.
The dealer tells me all tires have small pores which cause leaks and I should go to a tire firm to have nitrogen put in the tires. (He didn't say it would seal the tires but indicated it would solve my problem?) Almost all of the comments on your site do not speak favorably of this.