Kosel K1-TS, 15 x 7, 12.6 lbs, $150 each at Tire Rack[/b]
See, that's a good example of the "$$/weight" value ratio. Is a loss of 0.4 pounds (-3%) worth an extra $30 each (+25%) versus the regular K-1s? Or how about an extra $50 each (+50%) versus the $99 Kazera KZ-M? I certainly don't think so.

Faced with the choice of the 12.6# $99 KZ-M and 13# $149 K-1TS, I'd rather pocket the extra $200 and use it for much more efficient means of going 0.013437654 seconds per lap faster (like more track time, or maybe two extra spare wheels for rains...)

Like I said: $$/weight value scales takes a big dumper below 13 pounds...