Originally Posted by
aliasfox
One additional thought - how fresh was the GP5k when you measured it? If it's freshly mounted, I'd give it a day or two at-pressure to settle in before measuring. Maybe even leave the bike outside in the sun to allow the tire to 'relax' a bit.
All of my tires, from 23mm to 32mm, always look just a little... shy... when first mounted.
The tire expended maybe 0.5mm after a few rides.