Welcome to AF. The best addvice I can give as to removing wheels from diecast is to take the body off the base and see how the wheels are attached from the inside. Most of them are attached by a screw from the inside. Smaller scale diecast (1/24-1/64) could just have the wheels attached directly to the axle. In these cases you might be able to pull the wheel off or cut the axle in half and replace them with new axles with the new tires attached.
Scott