Nice - I had a ‘68 Speedster in the same Sky Blue and 17” camelback frame. Looks like yours has a nice cast stem - the ‘68 used a cheapo rolled style with lots of flex with the wide bars. Like your saddle upgrade, too.
I once tried a 559x18 rim with a 2.125 knobby on the back of a 20” Collegiate frame - it didn’t quite fit. I was more interested in finding out if a Tektro 559 caliper would work with the 559 BSD rim than putting any particular tire on there.
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