hello aspirant,

When a two-wheeler  turn along an unbanked road, the force of friction provides the centripetal force. The two wheeler leans inward to counteract a torque that tends to topple it outward. Firstly, friction cannot be relied upon to provide the necessary centripetal force on all road conditions. Secondly, the friction results in wear and tear of the tyres. On a banked road at a turn, any vehicle can negotiate the turn without depending on friction and without straining the tyres.

Hope this helps. All the best.