Originally Posted by
ClydeClydeson
Honestly, this is the best solution.
THe flaw with the formulas given above (except mine, of course) is that they (a) assume having a tire wider than 'ideal' is somehow a disadvantage on smooth surfaces, and that (b) the type of gravel you plan on riding is the only type you will ride. In fact, any drawbacks from wider tires is miniscule, especially if you add pressure for rides expected to be smooth or paved, and on rough or soft surfaces the wider the better. Anyhoo, isn't the whole point of gravel bikes to be able to take on roads and tracks with which you are unfamiliar? Wider tires mean you can turn down any road or trail without worry. 35mm tires, for instance, are pretty multi-purpose, but on the roughest of roads you need to proceed with great caution. 42 or 45mm tires are damn close to what we used on rigid mountain bikes in the 80s and 90s - they can go anywhere.
Cycling is great sport for those who love to continuously tinker with things whether it's tires, handlebars, saddles, gear setup, etc. There is a never ending list of things to tinker with. I certainly do plenty of that. I've tried plenty of tires and finally settled on my Specialized Pathfinder Pro size 42 which are fairly speedy on paved when needed. If I felt like I needed to be faster on my gravel bike on paved I would go with my Terreno Zero size 38 tires.
I think it just depends on what your goals are and preferences are. For most people in day to day riding wider is better and there are plenty of gravel tires that will at least do okay on paved surfaces.