This year is my 43rd year driving. I am also a home mechanic during that time. FORGET RUN FLAT TIRES.. THEY ARE NOT WORTH IT..
SPARE TIRE - Although a spare (or a doughnut) is nice as OEM, no one is stopping you from getting your own spare or doughnut from a junkyard. Changing a spare tire involve heavy physical exertion, getting overheated (or cold), and possibly bruising your hands, so I would not recommend the spare tire route to women or older people.... If you get a spare tire, you also need an "X" lug wrench (because an OEM tire iron is worthless), and a "rolling floor jack" (because the OEM jack is worthless), and gloves. If you do not have a spare but can take the wheel off, you may want to go to PLAN C..
NO SPARE TIRE - I would say that in 90+% of flats, you do not need to take the tire off the car (change the tire), so even "not strong" people can do the following...
PLAN A - Over the years almost ALL of my flats are the result of a foreign body (screw, bolt, and even wicker pieces) which has embedded itself into the tire an remains there. Then you are in a situation of a slow leak. To get home or to the garage... YOU WANT IT THERE, DONT REMOVE IT. All you really need there is a tire pressure gauge and a good electric air pump that you run from the cigarette lighter (with the engine running so you don't kill your battery). Fill up the tire to the right pressure. Then, you need to evaluate how bad the leak is. If you hear hissing, then you need plan B because the leak is large and you cannot drive the car too far before you need more air. If you do not hear hissing, then you are golden. I would then drive the car and check the pressure every 1/2 mile, 1 mile, 3 miles, 5 miles until you are where you want it to be to get safe. THIS IS NOT A REPAIR, BUT A WAY TO TEMPORARILY DRIVE THE CAR TO SAFETY... PS, if you are going TO work, and this worked, you could probably leave the car parked at work and repeat the pump thing if needed when you need to go home.
PLAN B - if you hear hissing when you inflate the tire, the tire is not good to drive, so you may want to call a tow truck. Or if you are a gambling person, use something that comes in a plastic squeeze bottle like "Green Slime" which is water soluble, and will not hurt your tires.... DO NOT USE "FIX_A_FLAT" or anything that comes in a CAN, smells like gasoline or is very sticky because that works by gluing the inside of the rubber tire, and no garage will spend an hour getting that crap out of your tire. Green slime washes away with just water. after putting in the SLIME, pump up the tire and IMMEDIATELY drive the car 50 -100 feet to coat the inside of the tire and see if the hissing has stopped. if it is still hissing, call the tow truck.
PLAN C - TIRE PLUGS - if you can take the tire off, and are a big strong 200lb gorilla, then carry a set of tire plugs and plug the tire and go home. I can post and example of how tire plugs are used if anyone is interested...