GMC ≫ SierraGMC Sierra 2500HD All Terrain X (2017, third generation) photosby Joshua ThompsonThe 2017 GMC Sierra 2500HD All Terrain X has black 18-inch wheels, LT275/65 offroad tires, styling upgrades, and a 6-liter V8 or 6.6-liter V8 turbo-diesel. ◄ PrevNext ►Credit: Jim Fets 2017 GMC Sierra 2500HD All Terrain X Tags:2500all terrain xgmchdsierrathird generation