On Wednesday, October 16, 2019 at 10:24:05 PM UTC-5, jbeattie wrote:

28mms sucks in loose gravel and dirt. Last weekend was gravel on 35mm and my cohorts were on 40mm

-- Jay Beattie.

Agree with Jay on this. Most gravel roads that are regularly used by cars can be ridden just fine with road bike tires. These gravel roads have two or three perfectly smooth strips of road about one and a half foot wide. Road tires work fine on these smooth surfaces. If dry. But any gravel road where the rock is actually completely covering the road, forget about road tires. You want big wide treaded tires. And let half the air out too.