tire pressure - again

wolfe10 wrote:
Effy,

You are correct, but perhaps overthinking this.

Indeed, with change in temperature, tire pressure changes (very little change with change in elevation).

SO, here is my recommendation:

Best-- weigh individual wheel positions and use heavier wheel position on each axle to go to your tire manufacturer's inflation chart. If only axle weights, see *1.

The chart will tell you the MINIMUM PSI for your given weight. Add 5 PSI to that minimum for a small safety margin.

*1 If only axle weights, you must add a fudge factor for side to side imbalance (say 5 PSI) as well as the 5 PSI for a small safety margin (as long as this does not exceed the wheel or tire limits).

And, yes, if you experience a 60 degree temperature swing, you WILL have to adjust tire pressure!

Remember when the tire manufacturers say PSI cold, they mean before driving at current ambient temperature.

Understood and I TOTALLY agree with all of that. So knowing that (devil's advocate here) we all run our tires at 5-8 psi higher or lower than we start by proxy of conditions out of our control. And despite weighing it and getting a baseline, that changes EVERY time you take a trip. And who weighs their rig every time? I would bet dollars to Donuts that most on this forum could be off their weighed weight by a hundred to a few hundred pounds bewteen trips. And the difference on the chart for my tires between 75 and 85 psi is 340#. That's not much in the grand scheme of things. One person and a cooler. And that's my point. Unless you know each time, or weigh it dry and weigh every article you put on or in your coach, frankly it's a guess. I read to weigh it like you are going on a trip. Well my trips vary. A weekend might be light. A week diving might require a lot of gear. A bike race might involve a few riders and half a dozen bikes, stands, tools etc. I might take some of my son's friends on a weekender. SOOO many variables that change, and of course the ambient temp.