Latest 40+ Tires 275 65 18 All Terrain. These 275/65/18 tires will provide you with excellent traction both on and off road and outperform your expectations. We want all our potential customers to make an educated purchase and feel confident with their selection. 275/65r18 tires have a diameter of 32.1, a section width of 10.8, and a wheel diameter of 18. Shop all 275/65r18 tires available at your local firestone complete auto care.