Hi,

I'm not suggesting you can simply calculate optimum tyre
pressures, but you can calculate / find ballpark numbers,
and pressures way off that are very low or usually very high.

You can find graphs for 15% tyre drop for different loads
and different tyre widths. The article states around 15%
was found to be ~ optimum. Some may prefer more
(lower pressure), some may prefer less (higher pressure),
but the general gist is for a lot more you lose far too
much in rolling resistance, and for a lot less you lose a
lot of comfort for some advantage on smooth but lose
out on rougher surfaces, the harder the tyre the more
easily you lose out on less than smooth surfaces.

Smaller wheels deform more than bigger wheels so
probably for folders the optimum is lower than 15%,
assuming rolling resistance is sidewall deformation.

I imagine having 100psi in a 1.5" front tyre on my
bike would be horrible, 50psi and 1.75" was too
hard and bouncy for the roads that I ride on.

I've got my back tyre near its (low) maximum
and set the front so it seems a little harder
over bumps and ripples, 20-25% lower.

Good tyre pressures are a compromise.

I'm just implying if I fitted 1.5" tyres to my
bike and pumped them both up to 100psi
because that is the max on the sidewalls,
I'd basically be losing out overall compared
to a more considered approach to settings.

rgds, sreten.