STBILITY Is an important element for a car to win a race.  and also prevents you from being disqualified.

these are the batteries i use

adequate stability for keeping your car on the track

if your car is unstable it can prevent you from winning a race. you guys might not belive this but i won a 2nd with an ultradash on a teck track using nimh batteries. with plastic rollers from the knockle breaker set with a metal pinion, hollow shaft and axles . the secret of this 2nd place win is that i used nimh and plastic rollers. the guy that got firs had all this okami stuff, as you know okami stuff is much better than tamiya.  heres my luky secret.(i didnt really know that my set up was going to win). the big secret was that my car had nimh batteries and plastic rollers. nimh batteries are way better than nicad because they have better power out put and are heavier better for stabilization. plastic rollers are really use less for speed tracks.  and for wheels i dont really use one ways . i wse large diameter wide tread i the bak and small narrow large at the back helpin stability but not top speed . for the rollers i put therubber rings on. easier to slow your car down like a break set when you tighten the roller down kind of tight. of the tires i use reston on ftont and lowbounce on the rear. this might sound crasy but i krzy glue my tires onto the wheel. cuz if your wheels fall of it kinda sucks. if you have money buy lock nut those are really important. and also be careful and dont strip the tire hole axle this is how wheels come off.