I changed out my 8” to 12” on my canoe trailer. I use the 10% rule.

Under inflate by 10% cold of max psi. This keeps the tire at near max when on the road and still provides both cushion and stability. Never had any issues.

 

Works for me 

You’ve got to love it.  A 2 page thread on trailer tire pressure.  Reminds me of the 2 page thread awhile back about storing a net on a kayak.

It's not so inconsequential when you consider the investment riding on those tiny tires....😀

14 hours ago, OldManLure said:

You’ve got to love it.  A 2 page thread on trailer tire pressure.  Reminds me of the 2 page thread awhile back about storing a net on a kayak.

Don’t even start looking at camper threads on tire pressures! 😵‍💫

Sir them to max pressure or close to it. Anything less and you will likely shear a sidewall at speed. 

I wish there was a tire engineer here to chime in. 

 

My thoughts are these. Determining the correct air pressure is more complicated than just setting it at max pressure. A large part of it is relative to the total load that the tires will support and keep within the design parameters of the tire. Heat build up, tire wear, and "ride" play important roles in making this determination. As with most things in life, this is more complicated than it appears at face level.

 

Whatever that "sweet spot" pressure is, it's safer to opt for a higher pressure (but not exceed the manufacturers max psi rating) at the expense of "ride" and tire wear. Tire wear might not be an important consideration because most tires age out long before tread wear warrants replacement. Finding that "sweet spot" psi is not so clear cut.

 

There are many methods to find it: puddle method, chalk method and even using a non contact thermometer. I believe they will all give us important pieces of the puzzle but might not paint the entire picture.

 

Determine that sweet spot pressure for your trailer tires is probably more complicated than most folks want to dip their beak in to. Set it and forget it and we're good to go. For many, that works for them. I'm plagued with the personality defect of having to know more and thinking things to death, much to the chagrin of my wife (and sometimes myself).  One benefit of torturing myself by chasing my tail is that I do learn more about a particular subject. Now I'll return to wondering what would happen if feathers tickled birds, how do you know when you're out of invisible ink, or if you;re driving at the speed of light and you turn your lights on, what happens? I need to know.......