|The WTB Riddler 37 on a Velocity A23|
I am going to try to stay away from repeating myself between the RidingGravel.com stuff and here, so this post should have some different information than that linked one does. Okay, so as far as this tire goes, here are some thoughts I have.
It has the oddity of being what size WTB says it is. Tire companies have, for years now, said such-and-such a tire is "x" inches wide and you could easily win bets by saying that the tire would not be that width, but skinnier. Almost every single time, this was the case. However; now it seems that, for whatever reasons, tires are more than likely going to actually be the size printed on the sidewalls, or be bigger than stated width. The Gravel King 40's are an example where I don't think anyone has measured one of those tires at 40mm. It is always reported to be wider than that.
Don't get me wrong, I love that things have switched around in that way concerning tires. It makes you feel like you got more for your hard earned dollars when your 40mm tire turns out to be more like a 42mm tire. That said, your now 42mm tire may not fit the bike you had intended it for. That's the flip side of this tire deal, and it can be a bummer. But just know that as far as the gravel bike tire class widths go, you should be getting what you paid for, and you'd better have the room for that tire in your bike!
The Riddler 37 is just such a tire. 37.2mm average width across both tires I measured, and that is on a "roadie width" A23 rim. I really feel the 36-37mm width tires are the sweet spot for most gravel. Not too heavy, but just wide enough to give you most of what a heavier 40mm tire would. Not as skinny and as low volume as a 33-35mm tire either, which you are more likely to get a harsher ride out of because you can't go so low on the pressures. Plus at that width, around here, tires start "hunting lines", cutting into and not rolling over gravel, and that's wasting energy.