When do you change the timing chain on a BMW Z3 2.2i?

The timing chain on a BMW Z3 2.2i generally does not require regular replacement like a timing belt, as it is designed to last the lifetime of the engine. However, if you notice symptoms such as unusual engine noise, poor performance, or if the vehicle has high mileage (over 100,000 miles), it may be prudent to have it inspected. It's also advisable to follow the manufacturer's maintenance schedule and consult with a qualified mechanic if you have concerns about the timing chain's condition.