2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 560

Changing a Flat Tire If a tire goes flat, avoid further tire and wheel damage by driving slowly to a level place. Turn on the hazard warning flashers. See Hazard Warning Flashers on page 4‑3. WARNING: (Continued) 3. If you have a four-wheel-drive vehicle, be sure the transfer case is in a drive gear - not in N (Neutral). 4. Turn off the engine and do not restart while the vehicle is raised. 5. Do not allow passengers to remain in the vehicle. To be even more certain the vehicle will not move, put blocks at the front and rear of the tire farthest away from the one being changed. That would be the tire on the other side, at the opposite end of the vehicle. When the vehicle has a flat tire (B), use the following example as a guide to assist you in the placement of wheel blocks (A). { WARNING: Changing a tire can be dangerous. The vehicle can slip off the jack and roll over or fall on you or other people. You and they could be badly injured or even killed. Find a level place to change your tire. To help prevent the vehicle from moving: 1. Set the parking brake firmly. 2. Put an automatic transmission shift lever in P (Park), or shift a manual transmission to 1 (First) or R (Reverse). (Continued) 6-100