SLOW punctures can be costly and are also dangerous.
Signs of a slow puncture
Check to see if any of your tyres have a different shape or seem to be sagging. You might also see some damage to the tyre’s side wall.
Make sure there aren’t any nails or other objects hiding in the tyre tread.
Before removing any object, know that the object may be plugging the leak it caused so removing it will cause the tyre to deflate. However, if you leave it in the tyre and continue driving on it, it may cause more damage to your tyre, so removing it will stop that.
Before removing the embedded object pour some water (soapy water, if you can) on the object and see if any bubbles form where the air escapes the tyre.
Slow punctures can also be caused by a faulty tyre valve. In this case, remove the tyre from the wheel rim and replace the faulty valve.
Driving on a damaged tyre is dangerous as it has a good chance of bursting.
Repair or replace the tyre
Change the punctured tyre with the spare. Take the damaged one to a tyre specialist who can repair or replace it.