TireRack.com price worse than local shop

[darxus]

Cost for four new tires from TireRack + shipping + install by local shop highly rated by TireRack: $662.42

Cost for the same tires from and installed by (different) local shop highly rated by Angie's List: $599.20.
($541.24 for tires, $57.96 for install.)

I'm pretty darn surprised the Tire Rack option is 10.6% more expensive than the local shop option.

I'm getting Michelin Primacy MXV4 (Grand Touring All-Season) (H rated) tires, because they're highly rated on TireRack.