In 1977, I purchased a SEKAI 2500 Grandtour with the smoking hot "Sekai Special" 300 gram gumwall tires, 27 x 1 1/8. That was a very light and narrow wired-on tire for that era.
For another $40, which I did not have as I was a poor high school sophomore, I could have purchased a SEKAI 2700 Grandtour Deluxe with the 27 x 1" "Sekai Special Ultralight" gumwall tires at the unbelievable weight of only 270 grams.
http://www.ece.ubc.ca/
At the time, most gumwall tires were 350 or 400 grams.
Both tires were almost certainly made by IRC or Panaracer, and even today a wired-on tire in that size is hardly lighter, even in the more competitive 700c tire. The main improvement since that time has been in the kevlar beads available on some times, and introduced within a year or two of 1977, I think.
- Don Gillies San Diego, CA, USA
P.S. if you have a pair of "Sekai Special" 27" (or even 700c) tires in your garage, would you consider selling them to me? I am restoring some SEKAI 4000's and it would be great to have some authentic tires for my restorations.