Thanks - I am really going to look closely.

********************************
The sheldon browne quote of the day:

Brown's Law Of Tire Sizing:

If two tires are marked with sizes that are mathematically equal,
but one is expressed as a decimal and the other as a fraction,
these two tires will not be interchangeable.

*********************************************
Patched - in grid:
Fractional sizes:

[TABLE="class: grid, width: 100%"]
[TR]
[TH]Fractional
[/TH]
[TH]ISO
[/TH]
[TH]Applications
[/TH]
[/TR]
[/TABLE]

[TABLE="class: grid, width: 100%"]
[TR]
[TD]24 x 1
[/TD]
[TD]520 mm
[/TD]
[TD]High performance wheels for smaller riders; Terry front
[/TD]
[/TR]
[TR]
[TD]24 x 1 1/8
[/TD]
[TD]520 mm or
540 mm!
[/TD]
[TD]Caveat emptor!
[/TD]
[/TR]
[TR]
[TD]24 x 1 1/4
[/TD]
[TD]547 mm
[/TD]
[TD]British or Schwinn Juvenile
[/TD]
[/TR]
[TR]
[TD]24 x 1 3/8
(S-5)
[/TD]
[TD]Schwinn Juvenile lightweights
[/TD]
[/TR]
[TR]
[TD]24 x 1 3/8
(E-5)
[/TD]
[TD]540 mm
[/TD]
[TD]British Juvenile, most wheelchairs
[/TD]
[/TR]
[/TABLE]

**********************************

The bike is a Raleigh Marathon (juvenile). What I thought was an inter-changable "Terry"-like front wheel tire may not be.

Thanks for the catch (not as easy as I thought)...I think I can still see tire size info on the original tire and assume tubes are going to be standard.