Scottsdale-based chain Discount Tire says its deal to acquire Tire Rack — a leading independent tire tester and consumer-direct wheel accessory source — is expected to close at the end of this year. The deal brings together two family-owned brands, and Discount Tire executives described it as a major step in its vision to advance the retail tire sector. Indiana-based Tire Rack has emerged over the years as a respected source of information for online wheel and accessories buyers.