Have 52" Bunton hydro, 16 HP Vanquard OHV twin; ground speed lacking for sulky operation. Want to replace 13x6.50-6 tires with 15x6.00-6 for a little more speed. 1.) Will these narrower tires fit on the existing rims? 2.) Are mower tires tricky to change; do I need special tools? Any tips?