The front mower castor wheels tires are about shot on my F525 and I am going to install new tires. They are mounted on 4 inch steel one piece wheels. The tire casing is EXTREMELY stiff and thick. The job looks like it is going to be a SOB to get done. I called the local tire shop and they refused to work on them stating that they are hateful and near impossible to change. Has anyone here done this before? I would appreciate any suggestions or techniques to change these tires. I included a diagram of the tire to give you a good idea as to what I am dealing with.