Basically what Matthew_Armeni is saying, is to balance your tires/wheels. This is a common thing for racers to do, as it decreases unpredictability in the truck's handling, and will allow the power to be put down smoother.
Guys I work with buy airplane prop balancers and mod them to use them as car/truck tire balancers. I'm pretty sure they use this one:
http://www3.towerhobbies.com/cgi-bin...?&I=LXD712&P=7
but I'm not sure what they do to make car/truck wheels fit on there.
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz