Search new + high quality used tires online. Size 315 40 R21 starting at: $51.4. Tires in stock: 58. Available brands: 7 with 20 models. All season: 46. Summer: 12.. 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!