dan foster

That just sounds like a rule-of-thumb for a particular type of plane or
perhaps was mentioning the FAA average per-pilot weight. In either case,
that isn't regulatory.

The authoritative rule is most likely going to be you doing the weight and
balance calculation for your plane, for yourself and the CFI's weight, and
amount of fuel loaded, figuring out density altitude, etc... and then if it
stays within an appropriate category (normal or utility) then it'll be safe
to fly.

It is true that if either (or both) persons are heavier than the average
170 pound number, you could need to make sure the plane has somewhat less
fuel loaded (eg, don't top off the tanks). It all depends on the exact
cir***stances.

I lucked out, though I'm a little heavier than I should be, and the CFI
is a little lighter than the average man, so it balances out nicely.

-Dan