Here's a scary thought- your car has a flat tire and you find there's no spare in the trunk. Well, this isn't all that unusual because guess what a lot of automakers did while we were sleeping - they eliminated the spare tire to reduce car weight and improve fuel usage! In addition, some automakers have been quietly substituting "run flat" tires for regular tires. The run flat tires are supposed to be good for driving when flat for about 50 miles at 50 miles per hour. Only thing wrong with that is driving those 50 miles normally destroys your tire, necessitating buying a new tire. And what if it's very late at night and there are no open service stations within those 50 miles.
Situations like this underline the need to carry your own emergency auto repair kit, in case auto road service is too far away or you are nowhere near an open service station. Ideally, you should carry a car battery jump starter with an air compressor, as well as a tube of tire sealant, at least 3 hazard signs and a tire gauge.
If you have no spare tire, you need to re-inflate or fix your existing tire wherever you are.
Put on your flashing lights and if you have emergency hazard signs, put one about 25 feet back from your car, and as far out towards the middle of the road to mark the outer edge of your car. The second should be back around 100 feet and closer to the edge of the road. The third should be back around 200 feet back at the edge of the highway.
Conventional wisdom is that you only need to put out your hazard warning signs if one of your left side tires is flat and you are kneeling down in the actual roadway to begin to repair the flat tire. Absolutely wrong!Even though you are on the other side of the car from the road, you can be seriously injured and even killed by a rear end collision by a driver who didn't notice your car. As a further precaution get your passengers out of the car and safely away from the roadway.
Start the Actual Tire Repair
Take off the tire's valve cap and start to re-inflate your flat tire with your car battery jump starter system with a built-in air compressor. Inflate the tire a bit. Stop, look and listen. Does it go flat again fairly quickly? Do you hear it hissing? If so, the odds are pretty good that you have a puncture. If you have a puncture, and not a huge one, there is another handy item in your kit - your tire sealant. This temporarily repairs flats in tubeless tires caused by punctures up to a quarter-inch. Inflate your tire up to its normal pressure - use your tire gauge to make certain. It may take running the car for a short distance to "spread" the goo properly inside the tire. If so, pull over at the first safe spot and check the air pressure. If you need to, top up the tire. Once you get back on the road, or home again, it would be a good idea to have a competent service station take a look at the tire that went flat.