Not a good shape for strength/stiffness/durability of the stays though. Fine enough with thick-wall stays, or low mileage and/or soft-pedaling riders. But I wouldn't do it on a lightweight frame that you're going to ride a lot.

I converted a Bridgestone road frame (recovered from the dumpster) to use 26" (559) balloon tires that way. Hammered an enormous piece of pipe in between the stays, which widened the dropout spacing. Then I clamped the pipe in position relative to the BB shell, and bent the stays back in at the dropout end to the correct OLD. Made very good clearance for what I seem to recall as a nominal 1.95" tire (not sure and I no longer have the bike). It was an awesome polo bike until a chainstay broke, at the indent. Admittedly, I made a deeper indent than most people would do on a road bike. I only needed it to work temporarily, and the frame being free meant the stakes were low.

Mark B