Road transport, as one of the most critical pillars of a country's economic and developmental infrastructure, accounts for a significant portion of national capital and plays a decisive role in economic sustainability and growth. Therefore, the optimal maintenance and preservation of road pavements are of particular importance. Although the design life of pavements in Iran is typically estimated to be between 10 and 20 years, in practice, distress often appears much earlier, usually within 5 to 6 years after opening to traffic—an issue that further highlights the need to revise design, construction, and maintenance practices for these vital infrastructures. Research indicates that one of the most significant factors contributing to such distress is vehicle overloading, particularly improper load distribution across axles. Failure to comply with regulatory requirements in this regard increases stress on the pavement and accelerates its deterioration. Accordingly, the present study analyzes and evaluates axle load distribution patterns using data recorded by a Weigh-in-Motion (WIM) system on the Tehran–Rudehen axis.

The analysis was conducted under four scenarios:

In the first scenario, all vehicles (both loaded and unloaded) were considered.

In the second scenario, only loaded vehicles were examined.

In the third scenario, overloaded vehicles were analyzed.

In the fourth scenario, overloaded axles within vehicles were considered.

The results showed that in the first and second scenarios, no overloading was observed. However, in the third scenario, 56.6% of vehicles were overloaded, and in the fourth scenario, 89.4% of axles carried loads exceeding the permissible limit. These findings indicate the significant impact of improper load distribution on increasing the load imposed on the pavement.