Tire Balancer
I remember a thread a while back about balancing tires and YES...it makes a massive difference in the handling of the car. So here's how I've eventually sorted out my tire balancer.
It is a propeller balancer with the simple addition to a spare wheel hub and wheel nut to center to tire on the balancing rod. A-main or I'm sure you can get the prop balancer at any decent hobby shop that deals in arial rc.