If the GP4000 are tight (what size?), I'd say the PR's probably won't fit. I think the 27 PR are wider than the 28 GP4k
They're 25's (actual width seems to be about 27mm) and there's enough clearance not to quite cause any rub. Was hoping 27's would come in at 27mm though.
@Roosterrun started
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If the GP4000 are tight (what size?), I'd say the PR's probably won't fit. I think the 27 PR are wider than the 28 GP4k