Oh I appreciate that over regulation and compensation culture mean you could never change a wheel (for the Firm). Facts however are facts, and the fact is the wheel and the nuts (which on most cars now are actually bolts) on a road car, race cars may be different, are designed to be changed at the roadside by hand. Now if the spare provided by the manufacturer is a proper spare wheel (not one of those silly thin things) then once you change it (correctly) by hand it will perform just as well as the ordinary wheel and as if it has been tightend by an air wrench, consequently there is no danger of it falling off. If you look at the manufacturers spec / service manual and find the torque setting and tighten the nut/bolt with a torque wrench you'll be surprised at how little tightness is needed. If you look at the length of the bolt, one of the reasons it's that long is so that if it works loose (which it won't provided, you use a wrench with the wheel on the ground) you'll get a lot of uncomfortable (and noisy) driving before the wheel comes off. That being said, wheels do come off for other reasons.