hello roadies!

i've just been looking into whether my new set of tires should be 20c or 23c, and i stumbled across this old thread Advantages of 700x23C or 700x20C tires? in it there was this:

(see * if you want to)

this got me thinking, is the above true? i'd like some of your opinions because i don't know if i've got my head totally around this. so here are my thoughts:

take a tire at (say) 100psi with no extra weight on it, and then put 200 pound load onto it**, will the tire deform so the contact patch is now 2 square inches (one square inch to support each 100lbs)? a "tire + inner tube" combo exhibits some compliance, but not total compliance*** with the pressure inside it. so isnt it more likely that the pressure inside the tire rises a bit, and the contact patch increases a bit, but not all the way to 2 square inches?

surely * (below) can't be true, else why do we all have such thin tires??

i feel like i'm missing something in this...




* this sort of implies that a thinner tire (vs. fatter tyre at the same psi) has to deform more when the same load is placed onto it - therefore a thinner tire has a greater rolling resistance than a fatter tyre because of the extra energy that i have to put in to deform and un-deform it constantly as it rolls.

** me + backpack somehow balanced using the wheel like some sort of bc wheel

*** if it was totally compliant, any increase in pressure would give a proportional increase in volume and the tire would not support any pressure greater than atmospheric.

p.s. didn't know what section to post this in, but it follows from the other post (from 2005) which was in this section. also, i'm sorry if this has been covered before, i havent read anything addressing this before, and i have read a lot of the posts in the forum (though i haven't posted much - i've found that questions i can answer, and ones that i would ask, have already been answered.)