I have ruined all 3 belts from small pebbles can does anyone have any idea as to the correct sizes of the stock belts beside 3mm, what can I do to make them stronger or is there another brand belt I can buy which is stronger ??

stronger belts will not stop teh pebble issue, it is part of the deal.. what will help the pebble issue is Sweeping the pebbles away. but that easier said than done... you would be farther ahead to see if you can mod a Thin plixiglass covers for the belt drive openings on the bottom of the chassis to help stop pebbles from gaining access to the belt areas.. you wont stop it 100%, but it will help imensly if possible. i have not looked to do this to my CT5 YET! but will be im sure. will post any results i find when i start to look at the possibilities of a mod for this..
hth
Tim