So I just bought a new mower. I am planning on using the old one for towing my utility cart around my property. There is no tread left on the turf tires. I would like to go with an aggressive tire since my property can get muddy in areas. Could you guys point me in the right direction for some new rubber? The rears are 20x8.00-8" and the fronts are 15 x 6.00-6". I don't know how to read tire sizes (took them out of the manual) and it looks like I have room to go with a slightly larger than stock tire. Chris