In the past the tube size should be the same as the tire size. In your case look for a 20x10-8 tube.

I gave up looking for a tube and bought some tire sealant.

Several brands exist. I think the one that I bought was berrymans. Slime is more common. Sears says theirs make the tires last longer.

Its been 3 or 4 years and I have used it on several tires and all are still holding air.

JerryO

These tires look dry rotted and may not seal with that tire sealant. The tread is still very good. I figured an inner tube might be more trouble free. It's just that the inner tube boxes list several different sizes making it confusing. Thanks dave

The multiple sizes listed on the package refer to the tire sizes that the tube will fit. If your tire size is listed (or if it falls in between 2 sizes that are listed) it will serve your tire. Did you actually identify the leaking point of the tire? If not, the leak may not be due to the "dry rot" condition of the tire. If your tire is leaking from a foreign object puncture you must find the object and remove it before installing a tube or it will puncture the tube and you're back to square # 1. I have read testimonials regarding the product known as "Slime". I use the stuff and have good results with it. I read where a user stated that Slime was the only way he could operate his machines. One of his customers lot had several large "thorn bearing trees" and the fallen twigs and thorns kept his tires flat until he began using Slime.