Preheat oven to 275 degrees F. In a large oven-safe saucepan, bring sugar and 3 cups water to a boil over medium heat; cook, stirring occasionally, until sugar is dissolved, about 5 minutes. Add wine, ginger, cinnamon, allspice, tea leaves, and orange zest; bring to a boil again. Add pears, remove from heat, and cover; transfer to oven.
Bake pears 1 1/2 hours, turning every half hour until tender but still crisp.
Remove from oven; let stand until cool enough to handle. Serve warm in cooking liquid.