The only downsides I have ran across with the TC4 and TC3 are is that some Tamiya rims don't fit. Some rims have support webbing on the back side that hit on the front arms when turned. The webbing can be trimmed to make them clear but it can be a pain to do. You could even clearance the arms but I have always done the rims. Also the wheel nuts are 8-32 thread which makes the nuts kinda big for some wheels.