Hmmm, could be wrong, but I think that Giant OCRs -- both alu. and composite -- come stock with long-reach brakes, and have clearance certainly for 28s, and I think 32s (esp. some, e.g. Panaracer Pasela, that are slightly undersized relative to claimed size). I recall reading a review of OCR 1 (I'm referring to current North American spec.) over on RBR in which the reviewer described using 32s for commuting. Might be worthwhile checking?