* Consult your owner's manual: This is the best source for specific information about your vehicle.
* Check the brake lines themselves: Look for markings stamped or etched onto the lines. These markings often indicate the diameter.
* Use a brake line measuring tool: Auto parts stores sell these tools for accurately measuring the inside diameter.
* Check a repair manual specific to your year and model: A Haynes or Chilton manual, for example, will have detailed specifications.
* Contact a Chevrolet dealer: They can access parts diagrams and specifications for your specific year and model.
Without the year of your Chevy Cheyenne, providing a definitive answer is impossible.