Features of the present disclosure implementing techniques that allow the user equipment (UE) to autonomously (e.g., without the network control) manage timing synchronization of a plurality of carriers using sidelink synchronization signal (SLSS) from one or more other UEs in order to identify a synchronization source. A synchronization source associated with a frequency carrier from a set of frequency carriers may be selected according to one or more SLSS sync source selection techniques or rules. For instance, the described solution may be utilized to enable UEs to autonomously perform V2X carrier aggregation (CA). In some examples, the synchronization carrier(s) to be searched may be determined based on the SLSS capability of the UE (e.g., transmission and reception of SLSS capabilities of the UE).