The Bit Char-G Guide for Bits!
Thanks to TheFanMan and TinyRC

Drift Sets:
The drift kit comes with an axle that has plastic molded tires. The gear ratio is orange. They cause your cars to spin easily, and corner very sharply. They are not well suited to racing etc. The pack also comes with a set of medium (stock) tires and a spring set (ranging from soft to hard). The springs are located on the front top of your chassis. The stock springs are white and the add-ons are red.

Tire Sets:
This set includes three different sets of tires. They are soft, medium, and hard. The soft tires have an off road style tread on them while the hard tires have a street tread. The mediums have no tread at all. They are much the same as the stock tires that come with cars, but are slightly harder. Note: The hard tires are very difficult to get on the front wheels! Be careful to not damage your wheels when putting them on or taking them off.

Gear/Axle Sets:
This set comes with three different gear ratios, consisting of an axle (without tires) and a matching colored gear. You cannot mix the gear colors or the car will not run due to gear binding. The gear colors are as follows:
Blue - good acceleration but not much top end. Good for climbing and technical tracks.
Orange - fair speed, fair acceleration. A good all around gear. This setup comes standard with all cars except special editions.
Teal - somewhat slow acceleration but great top end. Good for racing or wide open spaces. This setup comes standard with all special edition cars.

Motors:
There are four different speeds of motors. They are:
1.0 (blue) - comes standard with all newer cars. It is the slowest motor but has good torque. Recommended for beginners.
2.2 (yellow) - comes standard with most older cars. It can also be bought separately. This motor is the best all-around motor. It is reliable and fast, but not so fast as to be uncontrollable.
2.6 (orange) - comes standard with all special edition cars. It is faster, but not as reliable as the 2.2.
3.0 (red) - almost too fast for practical use. Recommended for short drag racing runs only. Less reliable than the 2.2.