Originally Posted by
topflightpro
The tire clearance thing is bike. IIRC, cross rules stipulate a max 35 tire width. (I could have that wrong, it's been a long time since I raced cross.) For gravel, a lot of people run 40+ tires. In fact, a lot of riders even run smaller wheels with bigger tires - essentially 26in MTB wheels and tires.
Yup. Many of the earlier gravel bikes only took ~40mm tires, but many of the new ones are accommodating 650b wheels and larger tires. Some even have provisions to alter the fork to compensate for the geometry change with different wheel sizes.