I wasn't suggesting a weighing exercise before every trip, just once to get a feel for the weight the tires are carrying on a typical trip. If you inflate to the pressure molded into the sidewall, you'll get wear in the center of the tread, resulting in tire replacement before you would have had to do had you used a more realistic pressure.
FYI, my Class A tires have a sidewall pressure number of 120 psi, but based on the weight of my rig in normal use, a pressure around 95 psi is appropriate for our normal departure loading. I've only weighed the rig once, since our loading is fairly consistent from one trip to the next.
BTW, if you search on this subject, you'll find a post from me about why nitrogen is used in airplane tires. As I said in that post, you only need to pay for nitrogen if your rig can accelerate to 150 mph in 2 miles and then you can fold the wheels up into a sealed box.
Frank and Eileen
No longer RVers or FR owners