Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This build uses fairly standard AD tank runes and masteries, with the exception of the Run Speed Quints. These allow Garen to catch literally any champion outside of Yi, and is the focal point of the build.
Ridiculous movement speed coupled with his massive 4200 hp, 60+% crit, and Atmas makes you a very very scary tank.
Rune Prices: (for anyone curious)
Marks: 9 x 410 = 3690
Seals: 9 x 205 = 1845
Glyphs: 9 x 205 = 1845
Quints: 3 x 2050 = 6150
Grand Total: 13,530
Thanks for looking ^_^