
Tubers that are slightly withered and wrinkled will probably still grow. I would go ahead and plant them. In the meantime, you can stop them from further drying out by lightly spraying them with water from a spray bottle.
Dahlias that are overwintered in a too-warm location tend to get dry and wrinkled - this is something to keep in mind when you store them for next year. For more information on storing dahlia tubers, please visit the following link:
https://www.gardeningknowhow.com/ornamental/bulbs/dahlia/storing-dahlia-tubers.htm