The frequency of changing bike tires depends on various factors, including the type of tire, riding conditions, rider weight, and maintenance practices. However, a general guideline is to replace bike tires after they have traveled between 2,000 and 5,000 kilometers (approximately 1,200 to 3,100 miles). This estimate can vary widely depending on the factors mentioned above, so it's important to regularly inspect your tires for signs of wear and tear, such as excessive tread wear or sidewall damage. Additionally, some high-performance tires may have a shorter lifespan due to their softer rubber compounds, while more durable touring or commuting tires can last longer. Ultimately, it's best to consult the specific tire manufacturer's recommendations and consult with a bike mechanic or expert for personalized advice.