Depends on what transmission you have also.
My 04 TJ with the 42rle auto read 60 on the speedo and 70 on the GPS. That was with 33" tires and stock 3.73 gears. I never changed my speedo gear, just dealt with it.
Now I am running 35" tires and 4.88 gears. My speedo matches the GPS! Glad I never changed the speedo gear.