Some 4.56 gear questions!!

i dont remember but their is something ither on bigblockdart.com or moparts that shows what gear to get for the speedo with the tire you have and gears... plus that 275/60/15 i believe is 28 in not 27 i have the same with bf radials t/a.....if you dont have the money for gears...get a bigger tire like 30in or something for the street