Highway pavements are an important component that provides comfort and safety for road users while riding. Therefore, by the authorities responsible for road operation, it is quite important that the level of service of the pavements is in good condition. In the study, it was aimed to investigate the relationship between the existing serviceability level of the pavements and the ride comfort for passenger cars, and to determine the limit values of IRI according to the comfort criteria described in the ISO 2631 standard. For this purpose, IRI measurements were made on a state road about 80 km long providing intercity connections and the road was divided into sections evaluated. In the same road sections, vibration data were measured in the vertical direction over the driver's seat in the vehicle at different ride speeds. The measurements were evaluated according to the ISO 2631 coded standard and the awz (frequency weighted root mean square in vertical direction) values were found. A mathematical model was developed using the artificial neural network method between the average ride speed and awz data of the assessed road sections, and the IRI data. By means of the developed model, the limits of IRI have been determined for different ride speeds depending on the comfort levels specified in the ISO standard. As a result of the analyses, it was determined that as the ride speed increases for comfortable riding, the IRI limit values decrease.