The Maxxis,Refuse, VittoriaTerreno Zero, and Panaracer GravelKing SS might be the closest comparable gravel tires, all with minimal tread and good puncture resistance. The Marathon Efficiency is on the heavier side and is available in widths up to 60 mm. I'm wondering about price and rolling resistance.
I will be interested in following this tire and seeing how well it tests. The problem with Schwalbe lately is that you don't really know if they have all their versions of Addix speed dialed in. Some are fast (the newest Thunderburt is the fastest ever) but others are middlin' to bad like with the G-One R. With this one being offered in the 28x2.0 it could be a nice replacement for the Speed, which they seem to still be making in Speedgrip.
According to Schwalbe's website, it use the Addix Race rubber compound, but if you are concerned about rolling resistance, wait a bit until the tire is tested.
Weight is comparable to the Almotion which rolls forever. Compound on the Almotion is Addix Tour vs this Addix Race. Not sure what either means. Schwalbe confuses me.
I couldn't resist buying a pair of Marathon Efficiency (in 40-622). As with most tube tires they mounted really easily, with no tools or blisters. After a few days at 50 psi on 30 mm (inside) rims they measure about 42.5 mm wide and 38 mm high. They should come very close to 40 mm wide on 22 to 25 mm rims.
They're marked 50 to 80 psi so I started at 50. That seemed like a lot for my 75 kg body and they did feel pretty hard. After a couple of rides I went down to 32/36 psi F/R which felt much more comfortable. Not as supple as tires with light casings and no protection.
I can't say anything authoritative without instruments but they roll well on pavement even at 32/36 psi. Handling is flawless and they're quiet. Not silent, at higher speeds something between a whistle and a hum is barely audible, but quieter than some slicks.
On dry, hard dirt and easy gravel climbing and braking traction are surprisingly good. Must be the rubber as they don't have much of a tread pattern. I'm too cautious to push it on corners.
My early impression is if you don't mind the weight and want 40, 50. or 55 mm tires with good protection these are worth a look. Something like a GP5000, Corsa N.EXT, Strada Bianca Pro, or RH Extralight would be lighter and feel more like a road tire. Something with a deeper tread pattern would be better on soft surfaces.
After putting 25 or 30 hours on the 40 mm Marathon Efficiency my opinion has drifted towards meh. The 34 to 36 mm road tires I have are definitely faster and the supple Corsa and Strada Bianca Pro are also more comfortable on bad pavement, even at 50% higher pressure. Off road the extra volume of the Efficiency helps but there's not enough tread to grip in soft stuff. My front wheel slid about a foot when I attempted a U-turn on a soft trail, fortunately I didn't fall.
On the plus side grip seems good on hard surfaces. I assume puncture resistance is a strong point but my other road tires are good enough. BRR should be testing the Efficiency in a couple of months, I'll be interested in their report.
