Just wanted to share because I'm really into good tires and wheels. My geared road bike( early 80's Viner) had been equipped with 25mm GP4000s, in yellow, they look great. A few weeks ago I hit something and ripped open the back tire. Seemingly impossible to find in colors, I replaced them with 26mm Grand Bois Cerf. Oh man these tires are so nice. I understand now why people like them so much. Put them to the test yesterday on a 300k over rough roads. No flats, no problems, seemed to float over all but the biggest bumps and pot holes. 100 psi front, 105 back. The bike itself just feels better. Nice tires make a difference, and even though people have said they are not as great with being flat proof, I have no problem with stopping to fix a puncture, and I rarely flat anyway.

I have a Viner from about 1980. Do you have any pictures?

Trying to wear down my Continental GP 4 season 28mm tires enough that I can justify ordering Grand Bois.

Great tire, but you have to be skinny. They can blow off a rim at 80psi.

That has not been my experience, I regularly run them at 95psi.