tire pressure - again

I plan on weighing this week. There are a few areas around that will do this. get my weights, and look it up on the grid. Thank you all for your input. (including you Dennis :) )But I will add this, Tire pressure changes constantly and is subjected to temperature and altitude. So an example is something I saw on a post a while ago and started a bit of this line of thinking. If I am in Fla on the day I leave to come home, and it's 80 degrees. I check psi (something I rarely do on a trip honestly) and it's at my prescribed psi based on weight. Actually the weight I think it is because things have changed since I left home. I might buy things, I might reduce weight (drinking more beer than I planned and thus emptying my cooler, we might have less food etc). A LOT of things can change my weight and often this could be a few hundred pounds. Anyway I leave Fla and it's set at PSI but I am guessing at my weight quite frankly. So are all of you. Unless you weigh it EVERY time you get behind the wheel. So I head home and at home it's 20 degrees. There is a very good chance now I am under psi by as much as 10. The inverse could be true. I might leave an area that's 20 degrees an when I get to my destination it's 80 and now based on the tire heating up ambient temp etc, I am over by 10 psi and riding on balloons. My point is, despite weighing it and getting spot on, at the end of the day you are only ever going to be close. It might be right when you start cold, but all bets are off after that. It can go down or up based on ambient temp,road surface, altitude, heck even wind pushing the coach and heating up one side more than another. What's the tolerable range? And all of this is out of your control. Playing devil's advocate here but this is real life scenarios and nothing you can control unless you check, weigh and reset at every stop on a trip. Just sayin.