Hi I am Andy from ansmann racing TEAM austria ,
this is not a stupid question.
If you are using the alu hubs , the cone of the cardan axle will cut into the hub, if you tighten the hex.
For your alu hubs take a deburrer or mill the hub from the inside.
Don`t use the spacers, which are included in the hex pack. There is a little play, that you need, because of braking into turn.
Now you can thighten the hex, and you can feel a big improvement on your car.
Sorry guys for my bad english but im from austria.
