Immerse 4 large jars in simmering water until pear butter is ready. Wash lids and rings in warm soapy water. Preheat oven to 400 degrees F (200 degrees C).
Mix pears, red wine, sugar, and ginger in a large bowl. Spread on a large baking sheet.
Bake in the preheated oven, stirring every 20 minutes, until pears are soft and mushy, about 2 hours.
Pack pear butter into hot, sterilized jars, filling to within 1/4 inch of the top. Run a clean knife or thin spatula around the insides of the jars to remove any air bubbles. Wipe rims with a moist paper towel to remove any residue. Top with lids and screw on rings.
Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower jars 2 inches apart into the boiling water using a holder. Pour in more boiling water to cover jars by at least 1 inch. Bring the water to a rolling boil, cover the pot, and process for 10 minutes.
Remove the jars from the stockpot and place onto a cloth-covered or wood surface, several inches apart, for 24 hours. Press the center of each lid with a finger to ensure the lid does not move up or down. Store in a cool, dark area.