It's not safe to drive with a flat tire as it can cause damage to the wheel and other parts of the car. If a car has a flat tire, it's recommended to stop driving immediately and call for roadside assistance. The duration a car can be driven with a flat tire varies depending on the speed and distance driven. However, driving on a flat tire for even a short distance can cause severe damage to the tire and rim. It's essential to check the tire pressure regularly and replace any damaged or worn-out tires promptly to ensure safe driving.