I have an 02 grizzly 660 with 1550 miles , so I pulled the front wheels today and looked at the brake pads. I have approx. 4mm of brake pad left. The service manual says to change when you get to the wear bars which is at approx. 1mm of pad left. How thick are the new pads? I'm just wondering how much I have worn away and am I ready for replacements.