In a large bowl, combine the shredded chicken, diced avocado, ranch dressing, cooked rice, lime juice, salt, and pepper. Mix until well combined.
Lay out the flour tortillas on a clean surface.
Divide the chicken mixture evenly among the tortillas, placing it in the center of each.
Top each filled tortilla with shredded lettuce and diced tomato.
Fold in the sides of the tortilla and then roll it up tightly from the bottom to the top to form a burrito.
If desired, heat a skillet over medium heat and place the burritos seam-side down. Cook for 2-3 minutes on each side until golden brown and heated through.
Serve the burritos with lime wedges on the side for squeezing over the top.