Heat grill. In small bowl, combine lime juice, oil, chili powder and garlic; mix well. Brush mixture over chicken breast halves, bell peppers and zucchini. Let stand at room temperature 10 minutes to marinate.
When ready to grill, place chicken, bell peppers and zucchini on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 8 to 10 minutes or until vegetables are tender, chicken is fork tender and juices run clear, turning once.
To serve, slice chicken and vegetables; place in center of each tortilla. Top with desired toppings; roll up.