Q: How would I know if I need to replace the rotors on my 2016 Mazda 6 sport without removing the tire?

Hello. Thank you for writing in. With the age of your vehicle, it is rather unlikely that you would have to replace the rotors already. The brake pads that stop the rotation of the rotors however do likely need to be changed at this point. Most brake pads are designed with a "wear indicator" tab which is designed to squeal when the pads wear down to a certain point. This may be the cause of some of your symptoms. Changing the brake pads can be done at home, and is not terribly complicated. Keep in mind that you will have to bleed the brakes afterwards. This is a process of eliminating any air in the system. Brakes are a huge component when it comes to vehicle safety, and the repair needs to be done by the book. If you are comfortable with these types of repairs, then you will should be able to get the job done with basic tools (tire iron, flat head screwdriver, sockets, brake fluid bleeder kit, and a few others). Changing the brake pads can be done with minimal tools, but with the right tools will be a lot easier.