Originally Posted by
Wildwood
The tires pictured in post#1 sure look wider than 26X1 3/8".

Or - just color me stupid.
Both can be true!
But I did a quick search and confirmed that that Murray had 26 x 1 3/8" tires. That was the default size for most "lightweight" (as opposed to cruiser) department store bikes in the '60s and '70s, including upright and drop bar models with either derailleur or internal hub gearing.
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You are always the same age inside.---Gertrude Stein
My aluminum bikes: Light, strong, cheap, and comfy.