For better traction on the rear there is really only 2 options, A set of tractor style bar lug, which can be really expensive, or a set of ATV tyres.
However, unfortunately there is not much available in more aggressive tyres, for that size. If you had the larger frame anniversary with 8" rims you could look at a set of quad bike tyres but there is not much for bikes or tractors with a 6" rim.
Personally I would be looking for a more modern mower with better brakes, the anniversary has really bad brakes which can make for a very bad day if the chain lets go.
Last edited by nath; 25/04/22 07:48 AM.