HX 531 welded eMTB rim, 30 mm wide – the ultimate all-rounder? In 29" or 27.5", with its 30 mm internal width, the HX 531 is perfect for heading into the unknown. Offering the ideal compromise between strength, weight and width, this mid-range rim can accommodate a wide range of tyre sizes and is the ideal choice for any eMTB built to tackle real mountain bike terrain.