Buy a subwoofer that comes with a box, its usually small depends on the size of the subwoofer, bolt your amp on the subwoofer box to safe space, and put Velcro between your subwoofer box and the carpet surface of your boot... that way, u can just unplug the wires, pull the subwoofer out and get access to your spare tyre.... Problems: - Not much of a problem in terms of access to your spare tyre, its mostly time of unplug wires from the amp, pulling the sub box out is easy - Problem in terms of sound quality: Really depends on how good your subwoofer and amp is, and how well the box was design, $$$ equals to sound quality lol, but you will be happy with the sound for those low range sound system...