A method for determining the surface condition on at least one rail head, in particular on its running surface, along a laid railway track formed by rails, wherein at least one rail plane is defined by the two rails, and wherein the following steps are performed: - provision of a measuring carriage with a carriage frame and rotatably mounted wheels on the carriage frame, wherein the carriage frame is supported by means of the wheels on at least one of the rails and is displaceable along the rails, - provision of a measuring unit with at least a first measuring arrangement with a measurement base carrier, a guide arrangement and at least one first sensor, said at least one first sensor being arranged on the measurement base carrier and the guide arrangement being arranged on the carriage frame, wherein furthermore the measurement base carrier is preferably guided by means of the guide arrangement in a displaceable way in a normal alignment with respect to the respective rail plane relative to the carriage frame, and - displacement of the measuring carriage along the rails and thereby determining the surface condition on at least one rail head of at least one rail, wherein during the displacement of the measuring carriage, the measurement base carrier including the at least one first sensor is mechanically supported on the at least one rail by means of a supporting device, and during the displacement of the measuring carriage, the at least one first sensor is constantly guided at a predetermined, fixed distance above the rail by means of the supporting device and with respect to the respective support position of the supporting device on the rail, characterized in that the wheels are arranged in pairs one behind the other on the measuring carriage in the direction of travel of the measuring carriage and of these a first and at least a second pair of wheels is formed, wherein the first pair of wheels is arranged at a first axial spacing from one another in the direction of travel of the measuring carriage and the second pair of wheels is arranged in the same direction at a second axial spacing from one another, wherein the first axial spacing and the second axial spacing are selected to be at least 20% different to each other, and a ratio of the two axial spacings (40, 41) to one another does not form a natural number. - provision of a measuring carriage with a carriage frame and rotatably mounted wheels on the carriage frame, wherein the carriage frame is supported by means of the wheels on at least one of the rails and is displaceable along the rails, - provision of a measuring unit with at least a first measuring arrangement with a measurement base carrier, a guide arrangement and at least one first sensor, said at least one first sensor being arranged on the measurement base carrier and the guide arrangement being arranged on the carriage frame, wherein furthermore the measurement base carrier is preferably guided by means of the guide arrangement in a displaceable way in a normal alignment with respect to the respective rail plane relative to the carriage frame, and - displacement of the measuring carriage along the rails and thereby determining the surface condition on at least one rail head of at least one rail, wherein during the displacement of the measuring carriage, the measurement base carrier including the at least one first sensor is mechanically supported on the at least one rail by means of a supporting device, and during the displacement of the measuring carriage, the at least one first sensor is constantly guided at a predetermined, fixed distance above the rail by means of the supporting device and with respect to the respective support position of the supporting device on the rail, characterized in that the wheels are arranged in pairs one behind the other on the measuring carriage in the direction of travel of the measuring carriage and of these a first and at least a second pair of wheels is formed, wherein the first pair of wheels is arranged at a first axial spacing from one another in the direction of travel of the measuring carriage and the second pair of wheels is arranged in the same direction at a second axial spacing from one another, wherein the first axial spacing and the second axial spacing are selected to be at least 20% different to each other, and a ratio of the two axial spacings (40, 41) to one another does not form a natural number.