The seatstay clearance @ 320mm from axle center is almost always greater than the chainstay clearance @ 320mm. So, so far so good, but you really have to take that chainstay measurement. And don't forget the fork blades, either! For Hetres, I recommend a clearance of no less than 46mm @ 320mm from axle center. This will provide ~3mm clearance between the tire and the chainstay. You can get away with less, but then starts getting risky.