Originally Posted by ralck
This is probably a really dumb thought, but is it possible to replace the ST's full size spare with a donut and smaller foam so the seats fold flat? Or is that a safety issue?
Theoretically it can be done, but its not necessarily a great idea as not only is it a temporary duty tire, the largest compact spare is still only about 4-4.5" wide vs the 7-8"+ of the standard 18" wheels (iirc they are 18"x8") so the load rating for the temporary spare might cause an issue (perhaps not, but its best to err on the side of caution). I definitely wouldn't recommend it on the driven axle especially as that could also cause uneven wear on the axles and cv joints for the duration that they are installed as the height and weight are so far from that of the normal wheel and tire combination. Although to be fair I wouldn't recommend that on even the regular Focus with its 15-18" wheels for the same reasons.
It would be better than removing the spare wheel all together and only having an inflator or a can of tire sealing compound that will be useless if the side wall is gone or if there is a large enough hole in the tire. Nevermind the fact that it is allegedly a pain in the neck to clean that garbage out of the wheel, and it may even damage the TPMS sensor, but that I don't know.