Whisk vinegar, olive oil, garlic, tarragon, and thyme together in a small bowl. Place chicken thighs in a gallon-sized resealable plastic bag and pour vinegar mixture over the chicken; turn to coat. Seal bag and let marinate at room temperature for 1 hour.
Preheat an outdoor grill for medium-high heat and lightly oil the grate. Remove chicken from marinade and discard marinade.
Grill chicken for 15 minutes, flipping every 5 minutes. Transfer chicken to a plate and let rest for 10 minutes before serving.