Originally Posted by
drewtk
That's where I come out. Now that I've had a gravel bike for a while, I'd want more than 38mm of clearance.
Trek says the 2019 Checkpoint can handle up to 38's. Trek revised the Checkpoint for 2020 to say it can handle up to 45's. While some people do run wider than 38's on their 2019 just fine, the bottom line is that the 2020 has more tire clearance.
I definitely prefer something larger than 38. I ride enough gravel events where there can be a wide variety of gravel including some short single track sections or just chunkier gravel. Much better with something 40 or higher.