Jeff, Bobby, Rusty, and Bill are “Tier 2 Series Champions” (Gold), but by age rules (Jeff as of August 4) are classified as Silver (Jeff) or Bronze (the other Cup champions listed over 60). As such, they are not eligible for professional driver status and are taking advantage of the rule to race in amateur races.
Cup champions at minimum are GOLD but may be PLATINUM.
Drivers upon 55 become at maximum SILVER. Jimmie Johnson with seven titles will not turn Silver until he is 60.
Thanks for that explanation, WHB.