Although there are ideals of rim width to tyre width, in practice the width of a tyre is very forgiving, for eg. the same wheel that takes a 28mm width tyre will probably hold a 50mm width tyre. BUT it is this 2nd number (thebead seat diameter ) which is critical to the tyre you need to fit your wheel.
Childrens 7 - 10. Childrens 9 - 12. The pedals and threads are precession made on the crank and are fully tested before they leave the factory. You must put the pedals on the bike correctly. If you are sitting on the bike, then put the right pedal on the right and left pedal on the left hand side.