Search new + high quality used tires online. Size 315 30 ZR21 starting at: $33.54. Tires in stock: 151. Available brands: 5 with 18 models. All season: 1. Summer: 150.. Selling all used tires at discount costs. All used tires go through 2 layers of inspection on specialized equipment. One year warranty + free shipping on all inventory ;) Happy shopping!