The reason I suggested BX tires of the correct rim size is that there are a lot of Kubota owners that use them as estate tractors. They get a little worn, rusty and they replace them with shiny new ones. See a lot for sale on FB marketplace. Tractor tires are not like car tires, they really don't lose traction as they wear. Loss of traction indicates the wrong style of tire is being used. Last for decades with proper care. Even new, Kubota tire/rim packages can be significantly less than MF.