I purchased a 17-inch Spacesaver spare tyre for my 2016 Mazda CX-5. Despite the fact that my vehicle had 19-inch tyres on it, the salesman assured me that this was OK. The issue was that the boot floor board had to have a polystyrene kit installed in order for the floor to be raised to fit it. This did not meet my expectations, therefore I made sure to always have a spare tyre in the trunk of my vehicle.
My new vehicle is a Mazda CX5 2019 Sports Nav+184 Auto AWD, and I just got it today. I decided to keep the 17-inch wheel for the next model, which will come equipped with a Bose subwoofer in the trunk. According to the handbook, I should be able to unscrew the subwuffer fixing bolt, position the wheel in that location, then replace the subwuffer and tighten the bolt through it to secure both components. As I have not had the opportunity to give it a thorough examination, I would be grateful to hear the opinions of anybody who has attempted this.