It's never good to put off repairs to your car indefinitely, as you may be putting added wear and tear on the engine and other parts by overlooking needed repairs and may be putting your safety at risk when on the road. Some repairs can wait until you can make a convenient appointment with a repair shop, whereas others are much more urgent and should be looked at immediately. While you never want to risk your safety if you think a repair might be urgent, note a few troubleshooting tips for determining if that service your car needs should be done immediately or if it can wait.
If your car's steering wheel vibrates slightly while driving, this usually means the tires are out of balance. You can often have them balanced as soon as possible and this fixes the problem. However, if the vibrations are so severe that you have a hard time holding the wheel, or you can tell that one wheel alone is vibrating, this may mean that a tire itself is coming loose; this should be serviced immediately.
If you hear grinding from the brakes, note if it's very subtle and goes away after a few minutes; they may just be wet and need to dry off. If the grinding continues while you drive, this typically means the pads and rotors are worn down and need immediate changing.
If you hear a hissing noise, you should stop the car and note where it's coming from; it may be a tire that is going flat and this should be changed immediately. If the hissing is coming from the front of the engine, the radiator may have sprung a leak. This needs immediate servicing so the radiator doesn't burst or your car doesn't overheat.
If the check engine light is on, this might mean a sensor is going bad and it will eventually wear out; if there are no changes to your car's performance, you might be able to put off this repair until it's convenient. If the brake light is on and you don't have the emergency brake engaged, this should be checked immediately—this usually signals a problem with the car's brakes, and they could fail at any time. If the thermostat gauge is on, you need to stop the car and let it cool, and then get it serviced immediately as driving it while too warm can cause the engine to seize up.