he suggested getting a bigger tire
and the problem with that suggestion
is that nobody makes a bigger tire for 27 inch rims
as far as a i know

27 inch wheels are fairly common on older bikes
almost all 10 speeds from the 60s 70s and 80s had them
but they have been almost entirely replaces by 700c wheels
which have a slightly smaller diameter
but have many many many options for tire sizes

wider tires can carry the same load as a narrower tire
but with less pressure

this generally gives a smoother ride
and more traction

the 1 3/8 wide tires you have
are very similar in size to 700 x 35c
which is a very very common size for city riding
and people are able to do all sorts of riding
carrying all sorts of loads

if you wanted to change the wheels intirely