Make the marinade. In a large mixing bowl combine chopped chipotle peppers, onions, beer, balsamic vinegar, apple cider vinegar, oil, maple syrup, and salt; whisk until completely incorporated.
Marinate the pineapple rings. Place pineapple rings in a ziploc bag and add ½-cup of the prepared marinade to the pineapples. Seal the bag and refrigerate for 4 hours.
Marinate the chicken. Place the chicken thighs in a large 1 gallon ziploc bag. Remove ½-cup of the marinade to use for later. Keep refrigerated. Add the remaining marinade to the chicken thighs; seal the bag and refrigerate for 4 hours.
Prep. Preheat the grill to 400˚F. Remove chicken thighs from ziploc; discard the marinade. Let the thighs sit at room temperature while preheating the grill.
Grill the chicken. Brush the grill grates with oil. Transfer the chicken thighs to the hot grill and place over direct heat; cook undisturbed for 5 minutes. Flip the chicken over; brush with the reserved marinade and continue to cook for 5 more minutes, or until the chicken is cooked through and internal temperature registers at 165˚F. Brush on more of the reserved marinade while the chicken is cooking.
Let it rest. Once they are cooked through, remove the chicken thighs from the grill and set them aside for 5 minutes. Keep them covered.
Grill the pineapple rings. While the chicken is cooking or resting, grill the pineapples on both sides until grill marks appear; about 1 to 2 minutes per side.
Serve. Place the chicken thighs on a plate and serve with the pineapple rings.
Notes
Nutritional Information Note: Since we are not actually consuming all of the marinade, the nutrition information is overestimated.