The 8 bolts are for bias ply tires and the later ones are for radials. The 8 bolts had magnesium runflats and the later ones are rubber. These are my observations; do not have a TM reference handy. The 8 bolt bias plys are not very popular and I was happy to switch to 12 bolt radials. My HMMWV drives, handles, tracks a lot better with radials.