Wiper blades work in harsh conditions, exposed to sunlight, dirt, ice, and frequent use. Replace them when they leave persistent streaks, skip across the glass, chatter, or fail to clear parts of your view after the windshield has been cleaned. A blade that is split, hardened, or visibly damaged should not be trusted to perform well in heavy rain.
Clean the windshield and blade edges first, since grime can imitate a worn blade. Use a damp soft cloth and avoid harsh solvents that may damage rubber or nearby finishes. If poor wiping continues, check the vehicle manual for the correct blade sizes and attachment types. Left and right blades may differ, and a rear wiper may use a separate design.
Follow the fitting instructions carefully and confirm each blade is locked in place before lowering the wiper arm onto the glass. Some arms can spring back and crack the windshield, so support them while changing blades. Test the wipers with washer fluid after installation. If the motor is noisy, the arms move unevenly, or the washer system fails, the issue may need more than new blades.