rim width

I've been told by racers that you want to go with the widest width possible. Some have used a "trick" by using a width wider than the max recommended.

YEAH THAT IS ONE OF THE CURRANT TRICKS TO KEEP THE TREAD FLAT. I JUST DONT REALLY WANT TO SCREW THE TIRES DOWN, WHICH U HAVE TO DO , OR RUN BEADELOCKS W/THE WIDER THAN NORMAL RIMS . ??????
The 10'' would be flush or stick out a little past the body/fenders , don't want it to look like a Mexican ricer . I always thot tires sticking out from under the body plain sucked , and looked like crap. Belong on mudders only.
More opinions ?