I like a dremel tool to cut them off. Some guys use a jig saw with a really fine tooth blade, and one guy used a roto zip (I dont know how the hell he went straight, but his look dang good!). And yes, you will get every drop of water on you that touches the tire. Just measure off what you think looks good, and tape it. I like taping because I can go straighter then with a sharpie marker or something similar. :thumbsup:
Here is a link to some of the cuts people have made...
HQ Link