This is the README for the fira package, version 4.2-2018-01-09.

This package provides LaTeX, pdfLaTeX, XeLaTeX and LuaLaTeX
support for the Fira Sans family of fonts (version 4.2)
and the Fira Mono family (version 3.2), 
designed by Erik Spiekermann and Ralph du Carrois of
Carrois Type Design. Fira Sans is available in seventeen
weights, but six of these are considered "experimental"; the
remaining eleven weights (with corresponding italics) are
supported with this package: Thin, UltraLight, ExtraLight,
Light, Book, Regular, Medium, SemiBold, Bold, ExtraBold,
Heavy. Fira Mono is available in three weights (regular, medium, bold);
there are no italics.

To install this package on a TDS-compliant TeX system
download the file "tex-archive"/install/fonts/fira.tds.zip
where the preferred URL for "tex-archive" is
http://mirrors.ctan.org. Unzip the archive at the root of an
appropriate texmf tree, likely a personal or local tree. If
necessary, update the file-name database (e.g., texhash).
Update the font-map files by enabling the Map file fira.map.

To use, add

\usepackage{FiraSans}

to the preamble of your document. These will activate Fira
Sans as he sans-serif text font. To activate it as the main
text font, use

\usepackage[sfdefault]{FiraSans}

Use 

\usepackage{FiraMono} 

to activate Fira Mono as the monospaced text font. The nomap
option will suppress the tex-text mapping of TeX "smart
quotes" and other ligatures into unicode glyphs for xeLaTeX
and luaLaTeX.

LuaLaTeX and xeLaTeX users who might prefer type1 fonts or
who wish to avoid fontspec may use the type1 option. 

Options scaled=<number> or scale=<number> may be used to
scale the fonts.

The default figure style for Fira Sans is
proportional-oldstyle, but the lining (or lf) option will
change the default to lining figures and the tabular (or
tf) option will change the default to tabular (monospaced)
figures. The default for Fira Mono is oldstyle.

Font encodings supported are OT1, T1, LY1 and TS1.

For Fira Sans, the medium, semibold, extrabold and heavy
options activate those series as the default bold series.
The book, light, extralight, ultralight and thin options
activate those series as the default regular series. For
Fira Mono, the medium option activates that series as the
default regular series.

Commands \firaoldstyle, \firalining, \firatabular,
\firaproportional, \firamonooldstyle and \firamonolining
allow for localized use of non-default figures. Superior
numbers are available using \sufigures. Commands \firathin,
\firalight etc. allow for localized use of those series.

The original OpenType fonts were obtained from

https://github.com/carrois/Fira

and are licensed under the SIL Open Font License, version
1.1; the text may be found in the doc directory. The
type1 versions were created using fontforge or cfftot1.
The support files were created using autoinst and are
licensed under the terms of the LaTeX Project Public
License. The maintainer of this package is Bob Tennent at
rdt(at)cs(dot)queensu(dot)ca.