If your RV has a rear-mounted spare tire, you'll need to lower it before you can change a flat. Here's how to do it: 1. Park your RV on level ground and set the emergency brake. 2. Locate the jack and lug wrench (usually stored underneath the RV). 3. Place the jack under the frame of the RV, in line with the spare tire. 4. Use the lug wrench to loosen all of the lug nuts on the flat tire (but don't remove them yet). 5. Crank up the jack until the flat tire is lifted off of the ground. 6. Remove all of the lug nuts and take off the flat tire. Put it aside for now.