6 wheels are awesome.... i would use them on ANY robot even 6" wheels and definitely 6 wheels are necessary for anything over 8" / pneumatic otherwise turning sucks.... the main thing is that the center wheel MUST be lower than the other two wheels otherwise its pretty pointless.... i guess you get more traction (and less turning) but with the center wheel our robot w/ 12" pneumatic tires, turned about 20 times better than our 2003 bot which had 4 wheels and 8" rubber tires
