They're the "normal" type of tyre/rim combo - with a steel or kevlar bead around the edge of the tyre that hooks under a groove in the rim (with inner tube or in some modern MTBs without ot form a tubeless setup).
The other type is tubular (commonly referred to as "tubs") where the inner tube is contained within a tyre carcase that is stitched together then glued to the tub specific rim.
