Flat tires can occur under a variety of circumstances. These circumstances will determine how the tire is fixed. If the flat occurs on a busy freeway without the possibility of driving the vehicle off the road then a towing company should be contacted for assistance. Waving down a fellow motorist to borrow a jack or walking to the nearest auto parts store to buy a jack are viable options.
Drive the vehicle until the flat tire is over open earth or soil. Turn the vehicle off and engage the emergency park brake. Find a stump, a log, a wood block or piece of concrete and slide it under the side of the axle closest to the flat tire. Stack blocking material up until it contacts the axle.
Begin digging away the soil beneath the flat tire with a digging tool such as your hands, a stick or the tire iron. Dig away the soil until the axle rests solidly on the blocking materials. Dig the hole down and out a few inches on all four sides of the tire. The hole needs to be dug deep enough and wide enough to remove the flat tire and accommodate the installation of the spare tire.
Bust the nuts on the tire with a tire iron until all nuts are removed. Pull the rim off the threaded studs and remove the flat tire from the hole. Set the spare tire in the hole and hoist it up onto the studs until they poke through the holes in the rim. Thread all of nuts back on and tighten them down with the tire iron.
Push a large rock down in front and in rear of the tire and fill the hole back up with the previously removed soil. Disengage the emergency parking brake. Start the vehicle and put it in a forward moving gear. Slowly give the vehicle gas until the spare tire climbs out of the hole and lifts the axle up off the blocking materials.
If the vehicle has a hard time getting out of the hole rock it back and forth by switching from a forward moving gear to the reverse gear.