The distance a tear will travel before it falls to the ground and stops. Certain items can max this stat without visually changing the stat.
Range is actually based on time in the air, making shot-speed affect range as increased speed means farther distance traveled.
Range has no maximum value, but there is a so called "soft-cap". After certain set values are reached the benefits gained from this stat start to decrease.
Usually, Range stops being useful once the distance traveled equals the length of a room. Items that allow tears to home in on enemies (The Magician, Spoon Bender, Telepathy For Dummies, and Sacred Heart), however, can utilize Range stats beyond that. Higher values allow homing tears to stay on screen longer and thus also give them more time to chase down their targets.