Two valve stem styles are available.
(Both types have the stem on the center line of the tubes.)

Straight Stem

90 Degree Stem

Select from the Inner Tube menu at the left for various sizes available.

Q) How do I select the inner tube tire I need? 

The best way is to look at the tire itself. The markings will be the same (usually) as the inner tube required. For example:

Tire is marked 3.00 x 4
Therefore, the inner tube required is a 300 x 4. 
The decimal is irrelevant.

Q) What do the numbers mean?

A tire marked 280/250 x 4 would be:

Max width of 2.8 inches
Minimum width of 2.5 inches
Fits on a 4" rim

Select from the Inner Tube menu at the left for various sizes available.

We also stock various sizes of replacement Tires & Wheel Rims.