Bicycle Mechanics - Inner tube size: 32x406, 20x1.2 schrader valve -- Do I have this correct?

Ok so I looked at a couple places for this tube and couldn't find it. A LBC had a 20x1.2, but only in presta. Can't find any on Amazon, ebay, or bicycletires.com.

Am I looking for this correctly? At first, I was strictly searching for 20x1.2, but then read some confusing articles about sizes expressed in fractions not being the same as those expressed in decimals, and the ISO #'s being more accurate.

I guess the question is, for my tire, which has 32x406 and 20x1.2 on the sidewall, which tube is the right one, and where can I buy it?

Tubes are basically air bladders, and far less critical in fit than tires. They'll stretch and fill whatever space there is and are usually labeled to fit more than one size of tire. You can safely use 20x1.2 as a reference to look for, but don't expect a prefect match. Might be 20x1.0-1.2, or 20x 1.2-1.5

Be cautious about fractional-sized tube, such as 20 x 1 1/8, which would indicate (usually but not always) that it's for a 451 20" wheel.

Pretty good selection of 20" tubes: http://hostelshoppe.com/cgi-bin/search.pl?category=706300

If you are in a hurry you can easily use presta tubes in a rim drilled for schrader valves. If you do not have a pump equipped to pump presta tubes (most bicycle pumps are equipped or can easily be converted) then you can buy a brass adapter from the LBS for $2. They can show you how to use it.

Hostel Shoppe has them. Actually they are listed as 20 X 1.25-1.35 (406mm) but that's definitely close enough.

Thanks guys. I'll stay away from the fractional sized tubes. I do see them at Hostel Shoppe, but I'm gonna check a couple more LBCs first now that I have the numbers cleared up. This is just for a spare, so there's no hurry (knock on wood!).