Car tire repair may be necessary when your car tire has a puncture or other problem which makes it unsafe to drive on. If the tire is damaged, the protective layer of air trapped within can escape and cause undue pressure to be put on your car's wheels. This can warp and bend the wheels and cause all kinds of problems, so it's important to keep your tires in good condition.
Your tire needs to be repaired if there is a hole in it which is allowing air to escape. Small punctures can be patched with relative ease, and your tire can then be refilled to the correct PSI and be as good as new. However, some tire problems are too serious to be simply repaired, and a replacement of the tire will be necessary. Very large punctures like slashes will require replacement. Tires also need to be replaced when the tread is too worn down for the tire to be completely safe. A technician can inspect your tires to tell you whether your tire needs a repair or to be replaced entirely.
Small tire repair kits are available from places like WalMart or various hardware stores. They should cost less than $20 and include patches, tire strings and other tools you need to patch your tire. It's important to note that these quick fixes are not meant to be permanent solutions; they are only meant to reinforce the tire and make it safe to drive to the nearest mechanic. To fix your tire completely, you will need to have a professional repair it.