While 700c and 29er tires are interchangeable what matters is the bead seat diameter, not the ERD.

The ERD is the distance that you need to calculate spoke length, the distance from a nipple to the one on the opposite side of the rim. Bead seat diameter is the diameter of the hook that holds the bead of the tire to the rim. ERD of a 700c rim is usually in the 600mm range, and it varies across rims, while the bead seat diameter of all 700c/29er rims is 622mm.

Chris