If you are using the GT-Tuned that comes with the kit, it is probably not necessary to glue the tires at all. I didn't, and I've had no issue with them coming off, migrating, or spinning in the wheels. If you have no vent holes it will add a bit of stiffness to the tires since the air will be trapped inside. If you want them softer, there's no reason you couldn't add the holes from inside the rim even after the tires are glued.
