I have a 2007 30' Arctic Fox 5'ver. A few years after I bought it I noticed one of my ST tires bulging out. After reading many horror stories of the ST tires blowing out I replaced them all with Mic...
Mine are about 4 years old. No cracks and they are just fine. Maybe you want to have the balance checked to make sure they didn't flat spot from sitting. I would have no problem using them. They are a truck tire and can also be used on a truck if you decide to change them out. No need to just throw them out..