Come on Roy, you can't compare torquing a cylinder head, which has to seal 200psi pressure with tightening a road wheel.
My Dad is a mechanic of 40 years, trained in the REME initially and then at Henlys. He taught me how to tighten wheel nuts and in all his years, has never seen a wheel fall off due to not tightening the nuts to the correct torque.
Well I'm sorry but I totally disagree, and if your father has not seen wheels fall off due to tightening problems then he hasn't that much experience it seems. There has been an on going investigation over many years by the likes of the IRTE and other bodies and many many instances of wheels coming off traced to tightening problems. There has been reams written about it, and you can look them up quite easily if you wish. I have also been out a number of times myself when I used to do breakdown work, so please don't tell me that it doesn't happen often. It is less now than it used to be, simply because of things implemented from those studies, but it still happens.
And yes I do compare it with head tightening but not for the reason you state - the point I'm making is that a wheel coming off is far more dangerous than a problem with the head gasket. The major point about using a torque wrench is to get equal torquing as well as the actual figure. In fact on non-stretch bolt tightening, often the actual figure was not that critical - as long as it was close, the important thing was the equality.
If you have a puncture in the pouring rain and fit your spare, are you going get your torque wrench out at the roadside?
If mine is in the car yes, but if not, I would do them as soon as I got home or to work, AND I would only travel at reduced speeds until they had been torqued, just as I would also get the spare pressure checked immediately after fitting it. I have seen so many people fit spares that they have no idea of the pressure or condition and then immediately drive at speeds of 90mph on motorways! The importance of wheels and tyres is far too under-rated by the public I'm afraid.
I agree, torquing does ensure they have reached the correct tightness, but there are other acceptable ways surely?
Not as far as I and others are concerned.
Roy