Conti GPs come in at 270g for a 700 x 23 tire.
For that weight you might as well get the Ultra Gatorskin in 700 x 25 (280g)
Why the 250g weight limit, if I may be so bold to inquire? The One-Way isn't a particularly light bike to begin with, and anything cutting down from those 600g stock monsters will be a significant reduction in rotating mass.
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"I feel like my world was classier before I found cyclocross."
- Mandi M.