I have a 1937 B that I am trying to get tires for, I noticed that most of the 4.00x15 or the 5.00x15 tires are called for only be tubeless. I know that the tractor calls for a tube to be used. Is there anyway to convert the tractor over to tube less or do you have to use a tube. Which is more original the 4.00 or the 5.00 and on the back is the 9.5 or the 11.2 more original? If anyone could help me out I would appreciate it.