Just an update here. Since the first post I contacted the dealer and asked if he had seen this before. His answer "I see studs break all the time". I also asked him as I see in my owners manual there is a picture of this tractor with ag tires and it looks like there is 6 bolts and then two studs with nuts opposite each other. I inquired if mine should have that setup. His answer was "If it came with studs it should have studs. I see them listed both ways".
So while waiting for parts to come in I raised the rear of the tractor and put a jack stand under it and it hasn't moved. A few days later another stud broke off on its own in the same spot as the others. Now I only have 4 studs left on one wheel. Interestingly we were talking how strange it is only one side has been breaking then low and behold while the tractor is raised on jack stands on the bad side we noticed a stud from the opposite side had broken. Same location as the other studs.
We raised the tractor and put it on jack stands. Removed both tires. There is a 1 1/4 spacer between the rim and the hub. If this puts stress on the studs I do not know. Most studs broke flush with the hub flange. To remove the broken studs I threaded a nut as far as I could on the back side of the flange and welded the nut to the broken stud. I then heated the broken stud with a torch and removed the stud out the back side.
I cleaned up all the threads with a M18 X 1.5 tap while waiting on parts.