I asked the question to R/C Champ, check it out below:
I am having problems understanding Kawahara wheel tyres:
a) Why is there tyre A and tyre B? What is difference for A and B?
The difference is,wheels design and its offset,Kawahara said A is 0 offset and B is +1 offset.
b) Why is there a tyre BA? What is difference?
BA is same design as B wheel but is same offset as A wheels.