This is A wheel type : 6 spokes, 26mm front, 30mm rear, 32mm rear
This is B wheel type : Star -12 spokes, 26mm front, 30mm rear, 32mm rear
This is BA wheel type : Star -12spokes, 26mm front, 30mm rear, 32mm rear, BUT WITH +1 mm OFFSET WIDER
My comments :
A wheel ( 6 spokes ) are more durable ( up to certain point ) because they are made from more flexible plastic. They are softer rims, very good when you are looking more extra grip.
B and BA wheel ( star -12 spokes ) are made from harder plastic, thus less flexible and quite easy to deform if you hit side wall too often. The rubber foam is more condensed than A wheel., and has taller side wall. Use this for super grippy track, for longer main final. <--- this is personal preference / strategy.
This is my personal preference, my taste for my home track. I don't know yours.
I personally prefer A wheel type.
For Xray NT1, I use 26mm and 32mm, 37 shore front and 40 - 42shore rear.
For MTX4, I use 26mm and 32mm, 37 shore front and 37 - 40 shore rear.