Someone recently posted that they had been told the Tufo Diamond nominal 28mm tubular measured only 25mm wide. I just bought a few of these to evaluate them, and mounted a pair on my recently rebuilt 1974 Raleigh Competition. This is the Diamond 28, nominal 28mm, and I yesterday measured it at 29mm inflated to 90psi on a classic Mavic tubular rim. AFAIK, the Diamond is only available in 28 and 30mm nominal width, but maybe there might have been a narrower one available in the past.
Very nice tire BTW. 90 psi, available in classic black tread with tan sidewall. Too bad it isn't available in a ribbed road tread as well as the diamond cyclocross tread.
I've actually never ridden a wide tubular before, never owned del Mondos, usually rode Clement Criterium or similar width "In The Day". I must say the feel of these wide Tufos is excellent. A tubular of this width may very well be the optimum tire for the type of riding most of us here actually do.
Big Spring, TX