This expression, which alludes to an unneeded wheel on a four-wheel vehicle, may have originated as long ago as , when Thomas Dekker wrote Match Me in London: In glancing our eye over the country, we cannot help receiving the perhaps erroneous impression that in relation to the great system, some of these institutions are too much like the fifth wheel to a coach.
From 'A Woman,' England, the Civilizer: Her History Developed in Its Principles Vice pollution, luxury, misery, vanity, deforming the face of society; and indigence stealing on the land preparing for pauperism. In Ireland the sword of desolation. In Scotland the canker of corruption. One chained to the car of the victor.
The other sold by her children. I believe the true remedy is the one suggested by the gentleman from Milton, Mr. Churchill, because it does not enter into details which ought not to be incorporated into the Constitution. I believe the true remedy is to be found in abolishing the council, for I do think that it is like a fifth wheel to a coach, entirely unnecessary in what is called the glorious 19th century, and for which there is no occasion, and I am decidedly inclined to the opinion that the government can be better administered without than with it.
The office of County Superintendent, besides being very burthensome, appears like the fifth wheel to a carriage, that is to say, if not injurious, it is at least useless. And couldn't we arrange a time — you, too, Betsy, I want to see you as well! You must be there — you must hear a good part of what I have to say. Clarke also accompanied the North-West brigade, on his way to Astoria. With the craft peculiar to Indian traders, they had crammed down Mr.
Clarke's throat that nothing could be done at Astoria without him, although his accompanying them was like the third wheel to a cart; but it answered their purpose: Clarke found out, when it was too late, that he had been duped. The difference in this last example, clearly, is that the image is of a two-wheeled cart with an extra third wheel, rather than of a four-wheeled coach or carriage with an extra fifth wheel. Ngram evidence of recent changes in idiomatic usage An Ngram chart of "like a fifth wheel" blue line versus "like a third wheel" red line for the period — looks like this: As the chart indicates, the ascent of "like a third wheel" since and especially since the middle s has been quite dramatic.
I suspect that the change is due to increasing use of the phrase in situations involving a presumably romantic couple plus a third person; under those particular circumstances, equating the odd person out with "a fifth wheel" poses a numerical problem, given that only three "wheels" are present. Conclusions The rapid rise of "like a third wheel" indicates that this version of the idiom has gained considerable momentum in popular usage since Still, usage of "like a fifth wheel" remains quite popular, too, so if we are in a transitional phase from having "like a fifth wheel" as the dominant form to having "like a third wheel" as the dominant form, we are only now at the crossover point in popularity between the two in published writing, anyway.
So, the answer to the poster's question, "If you are the "extra" person in a situation, are you the third wheel or the fifth wheel? At the moment, with the blessing of popular usage, you may invoke either sort of vehicle, and therefore you may be justifiably claim to be either the third wheel or the fifth wheel on it.