When should you seek advice? If your tyres become damaged on the main part or side walls they may need to be replaced. Most tyres have warning indicators on them to let you know when they will need changing (they are normally small rubber ridges below the main tread). You will need good lighting to see them and may have to rotate the wheels to locate them. If the indicator is the same level as the tread this suggests it's time to change the tyre.
Check your car handbook for correct tyre pressure depending on speed and load and adjust as necessary.
If damage is visible from kerb impact consult a tyre dealer, as damage to sidewalls and wheel rims can result in slow leaks.
If tyre wear looks uneven the wheels may be misaligned and need realigning. Keep wheel removal tools in good condition and accessible.
Use a mild detergent, such as car shampoo, on your tyres and rinse thoroughly. Avoid the use of a pressure washer directly on tyres as this can damage the cord structure.