you have to cut out the wheel wells, or do like the one pictured above and raise the stock ugly factory stuff up to give clearance. depending on the wheel offset, when aired out, the outside fo the tire could hit the bed sides. not a big deal, but will burn off any paint or primer it rubs on when dragging.
http://ifitsgotwheels.com/thumbs/b100.html" border="0" alt="" />
http://ifitsgotwheels.com/thumbs/thumbs_images/b122.jpg http://ifitsgotwheels.com/thumbs/thumbs_images/b136.jpg
http://ifitsgotwheels.com/thumbs/thumbs_images/b91.jpg you can see the primered area on the bedside that would burn off on one of these pics..