Q:

When do words like "Rewirable" keep the 'e' from "Rewire"?

I was spelling "rewirable" earlier and could've sworn it should be spelled 'rewireable' but google said otherwise.  Whats the deal here?  I never paid a lot of attention in my english classes throughout school so I don't always know the correct terminology or names for different parts of speech. 
Thanks

A:

Ngram viewer shows NO instances of "rewirable" in the American English corpus. British English shows a real horserace between the two forms, with "rewireable" ahead through the turn (1950s), and then "rewirable" leading for awhile in the backstretch (1960s & 1970s), neck-and-neck through the last turn to the homestretch, and "rewireable" pulling ahead in the end (1990s–present)
So it looks like "rewireable" is now the favored spelling on both sides of the pond. In written publications anyway. As for which spelling you see on the internet. . .  "YourMileageMayVary".

