I mocked these up on a 800EX (60inch), and the factory fender flares are used as part of the mounting solution. But, my friend that has the Zforce 500 trail had the same issue, and did the following: Bought and installed a set of 800ex fenders (these are pretty cheap from the dealer...I want to say like 30.00 each) then to boost the stability a little bit,, they installed 2 in wheel spacers on each corner. Worked really well, with very minimal splash or splatter..Plus you get the added benefit of having a 54" wide track.