I stand 5’ 10" tall. Why do we say five *foot *ten instead of five *feet *ten?
Not an expert, but in the past the singular was used for many measurements, e.g. “The store is five mile down the road”.
:dubious: Hmmm… As I sat here contemplating the OP’s question, I read the above to my SO… in reading it I said, “I stand five feet, ten inches tall”…
Just who is this “we” you are referring to? 
Just sayin’…
All “snarkiness” aside, I’ve said it both ways. I can’t really give you a reason for “waffling” back and forth like that. I think I tend to use whichever term sounds “grammatically correct” in my head, as I’m about to say it out loud. 
Just like you, that’s why I asked the question. I stand five feet ten inches but I climb a fourteen foot ladder to get on the roof. And, please, just to head off any lameass posts, don’t tell me you won’t touch this question with a ten foot pole. I’m 5280 *feet *ahead of you on that.
I’ve never heard this. I’d say five miles down the road.
Adjectives are rarely modified for the plural in English.
But you would say a five-mile stretch, no?
Touche’! Well put, sir! 
It’s common enough:
This.
When the measurement is used adjectivally it is (usually) in the singular and hyphenated.
…I climb a fourteen-foot-tall ladder… or, one cay say, “The ladder I climb is fourteen feet tall.”
…won’t touch it with a ten-foot[-long] pole… or, The pole which I use to distance myself from things is ten feet long.
…you would say a five-mile[-long] stretch, no? or, That stretch of distance is five miles long.
Regards,
Toucanna
Grammar Nazi-in-Training (note hyphenation) Argh! Doing it again! Must stop!
But he said in the past…
This is dating back to a dimly remembered Historical Linguistics class 25 years ago, but I remember the Professor saying that it is a fossilised remnant of the (now lost) Genitive Plural case (where five miles would have been expressed as if it was “five of miles”, but using the GP ending -a: five mila)
As a result of Old English’s collision and intermingling with Norman French after 1066 to eventually form Middle English, the English language’s system of case endings was greatly simplified, with most of the Germanic case endings disappearing.
However, some remained in certain established phrases (and he specifically used as his example “X mile down the road”, putting on a farmer-type accent.)
OT: I find these fossilised forms fascinating - another example he gave was “buying a pig in a poke”, where poke is a vanished word meaning bag or pouch that now survives only in its diminutive form of “pocket” (originally “pokette”).
As do I, sir!
I’m rather fond of old “Colloquialisms”, and try to use them whenever possible.
It gets me a lot of strange/confused looks from younger people, while some older folks seem to enjoy hearing them used. 
(Or at the very least, understand what they mean. ;)) One that I use regularly is, “fair to middling”. (It’s used in response to a query of “How’re you doing, today?”, as in “Oh, fair to middling… could be better… could be worse.”) IIRC the term dates back to the mid 1800’s from the “deep South”, and was used as a grade description for raw cotton. I heard it used by older people quite often when I was a small child, when visiting “kinfolk” in North Central Louisiana. Sadly, it’s not used nearly as frequently, as it once was. 
(They had a way of mangling the English language that I found quite unique and charming! :p)
“Fair to middling” is not particular to the Deep South, or even to the US. It was commonplace in Ireland when I was growing up, and still is. (I(doubt that it would evoke a strange/confused look from anyone.) And the OED has British cites going back to 1860. It may have been used in the southern US for grading cotton, but I suspect that’s just because cotton was what they were mostly interested in grading there. Elsewhere it had a wider use for grading produce of various kinds.
Well done, sir! Ignorance, successfully fought! I thank you for the correction!
In this case ‘five-mile’ is a single word (or the two words are used as a single word), for a unit of measure that is 26,400 feet long. Also used as a adjective modifying the noun stretch
Singular measurements are the norm in Northern English, in my experience.
10 ounce of sugar.
Fifty mile.
200 mile an hour.
10 foot of wood.
50 centimetre of cloth.
etc.
Actually, the last one can go either way. It seems to be Imperial measurements especially that are treated this way, and metric is sometimes used with a standard plural and sometimes not.
I normally hear “feet” when it doesn’t include inches, but “foot” when it does.
“Is he five foot eleven?”
“No, he’s six feet tall.”
There’s also a difference between American and British English. I still wince when here a Brit say that he weighs 175 pound. At least then he’s not talking about how many stone[s] he weighs…
Actually, English starting losing/simplifying its case endings long before 1066. Part of it was the direction almost all European languages were going – even vulgar (i.e., spoken) Latin during the late Roman Empire. But mostly, this happened during the transition from Old English to Middle English, largely due to the influx of Danish speakers (8th century? something like that) who spoke English as a second language, and raised their children to speak that simplified English as their first language.*
(*You can see a similar situation going on in places like Malaysia today, where many second-language-English speakers are raising their kids to speak a yet more “simplified” English – “Manglish”, some call it – as their first language. Manglish dispenses with many of the “little” words, e.g., “What you want?” in place of “What do you want?”)