Preheat the oven to 250°F. Rinse the racks of ribs with cold water to remove any grit. Pat dry.
Place a sheet of aluminium foil that's about 4 inches longer than the ribs on each side. Sprinkle the ribs liberally with either rib rub (see notes) or salt on each side. Place the sliced garlic and thyme on top of the ribs.
Place another sheet of aluminum foil on top of the ribs. Fold the aluminium foil in, starting on the sides, so the ribs are packaged up and no juices can escape. Place the packaged ribs on a baking sheet with the back of the ribs down, so they make a U shape. It's important they are placed like this so that they can sit in their juices. Place in the oven and slow cook for 5 hours.
While the ribs are cooking make the Peach Bourbon BBQ Sauce. Place the peaches on a cutting board and roughly chop them. (If you are using fresh peaches see notes above)
In a medium saucepan set over medium heat, add the olive oil. When hot add the onion. Cook until translucent, around 5 minutes. Add the garlic, jalapeno, chipotle pepper and peaches. Cook an additional 5 minutes until everything has softened up. Add the apple cider vinegar, water, bourbon, tomato paste, honey, Dijon Mustard, light brown sugar and Worcestershire sauce. Bring the sauce to a simmer and and then cover and turn the heat to low. Cook covered for an additional 10 minutes. The sauce will thicken up a bit.
With an immersion blender, blend the sauce together. If you do not have an immersion blender carefully transfer the sauce to a regular blender and blend until smooth, then transfer back to the pot.
Preheat your grill on medium heat and place a grill mat down. After 5 hours remove the ribs from the oven. Cover them liberally with the BBQ sauce. Transfer them to the grill and cook for an additional 5 minutes so they crisp up a bit. Pull them off the grill and cover with more sauce. Serve hot.
