Found this:
"For example, the publication notes that a Boeing 737's four main tires cost $1,500 each. However, Boeing 777s are somewhat more expensive to equip in this regard, with each of the widebody's 12 main tires costing $6,000."
Looks like you are right on that. The article I read said $100K per tire versus $6K per tire you mention. It makes sense the total cost would be closer to $100K instead of $1M every 3 months..