the mounting depth of the type x is 119, mine are 168 deep but im sure there was an easy 50 mm between my subs and the bottom of the box. so if your keen its worth measuring. its well worth it. having bass but still being able to throw the pram in the car or whatever/whoever(lol not really) i please is great.
according to our rta laws you do not need a spare wheel in the car, and if you do, it does not need to meet any road worthy requirements such as minimum tread and stuff