Bicycle Mechanics - Using a 24x1.75" wheel vs. a 24x1 3/8"

Will this work? The difference is only 3/8" in width? Seems like it would be fine. I have a junior boys road bike that currently has 24x1 3/8" (540mm Euro standard?), was wondering if I could just use a pre-built 24x1.75" wheel with a 24x1 3/8" tire or even a 24x1.75" tire. I know where to order the 24x1.75" but not the other. Seems like it should be fine but I don't wanna order the wheels and have them be useless. Thanks in advance for any help.

Will this work? The difference is only 3/8" in width? Seems like it would be fine. I have a junior boys road bike that currently has 24x1 3/8" (540mm Euro standard?), was wondering if I could just use a pre-built 24x1.75" wheel with a 24x1 3/8" tire or even a 24x1.75" tire. I know where to order the 24x1.75" but not the other. Seems like it should be fine but I don't wanna order the wheels and have them be useless. Thanks in advance for any help.
A 24 x 1 3/8 is not even close to being interchangeable with a 24 x 1.75. Your bead seat diameter for the 24 x 1 3/8 is 540 mm vs 507.
24 x 1 3/8 is used primarily on wheelchairs.

http://www.sheldonbrown.com/tire-sizing.html

24 x 1 3/8" has a 547mm bead seat diameter, while 24 x 1.75 has a 520mm bead seat diameter.

The tires and rim must match. Using a smaller 24 x 1.75 will make the bike sit lower to the ground and you'll probably get pedal strike very easily.

No. Sounds similar, but the tires are meant for different rim diameters. Your 24x1-3/8" tire mounts to a 540mm rim, but the 24x1.75" mounts to 507mm.

Check out this: http://sheldonbrown.com/tire-sizing.html

I guess I should rephrase the question, it seems like a 24x1.75" wheel would fit a junior road bike just fine, I could use the corresponding 24x1.75" tire that is sold with it. Is there anything wrong with using this slightly wider wheel on this road bike? I'm just trying to get wheels that will fit a junior road bike I guess that's really the question.

As long as it's meant for the same diameter rim, it'll probably be okay. Look at the Sheldon brown link above and scroll down to Width Considerations (the red and green chart). Edit: I didn't read your last question very well. Like sonatageek says below, just try and see. You're going to a slightly smaller wheel, so the brake may not reach, but if it fits, it's fine.

I would think as long as there is clearance for the wheel in the frame you would be fine. This doesn't sound like it would have the brake reach issues people have when going from 27" to 700c.

I am looking at doing something like this, but sort of reversed. I have an old mountain bike frame that I am thinking about setting up with a 26x1 3/8 3 speed wheel from a salvaged bike. It will need another spacer, but fits in the drop outs fine.