I have been using Rim Guard in my Tn for a couple of years with good results. It is available from some ag tractor dealers. This link will take you to the company web site which has a dealer locator. Rim Guard "Ballaststar"
The post I was creating while the other one was being posted appears to be for a distributor. the other one appears to be the manufacturer. If you look at my post it has a dealer locator.