The outer contact area is less rounded (flattened) and the flat angular bottom offers a perfect form fit

which is why he wanted something a little different

Get yourself a set of single-speed spacers

You'll wonder how you ever got along without it

Schwalbe Marathon Plus MTB Tyre - Black - Reflex - Wirebead - SmartGuard - E-50 - Addix - Performance - 2.10 Inch - 27.5 Inch Exclusive The outer contact area isThe most puncture resistant MTB tyre approved for fast e bikes, with ECE R75 mark. On the central ribs it rolls easily over hard paths, while strong outer lugs give great off road traction. The SmartGuard provides superior puncture protection, with good visibility even in the dark. It is impossible to guarantee that a flat will never happen, but the Marathon Plus has the best defence against everyday tyre wreckers such as glass, flints or metal