I never head of foam fill.. I asked the place where I bought it from and they told me the tire will be made solid for the same cost or maybe a little more then the cost of new tires... BTW The green slime works great.. Just make sure you do not get a big hole in it like I did.. Ewww Green slime all over me and the tractor... /forums/images/graemlins/frown.gif Ran over a piece of rebar I think.. Made a nice hole...