Originally Posted by
Steve B.
I use the largest tire that'll fit
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.