In our world, getting a flat front tire is not fun. That&'s why all our heavy-duty mowers have large, flat-free casters with deep-groove ball bearings and bearing caps. The tires are molded rubber with a small, hollow section to soften the ride. The large, well-sealed, deep-grove bearings don&'t require maintenance and almost always outlast the tire. The bearing caps keep twine and landscape flags from getting wrapped around the axle and damaging the bearings. Walk behinds use flat-free tires mounted on caged roller bearings and the Stander BTM uses pneumatic tires on sealed ball bearings.