Method for determining the material layer thickness of material plies in the production of tyre components comprising the following steps: a) providing a tyre component by a device for producing tyre components, the tyre component being produced in the form of a material ply and as a continuous material, b) continuously conveying the tyre component along a conveying section, a terahertz sensor being arranged above and/or below the tyre component, the terahertz sensor being arranged on a frame, c) carrying out a continuous material layer thickness measurement on the tyre component, the terahertz sensor being moved back and forth transversely in relation to the conveying direction above the tyre component and the terahertz sensor thereby being moved on the frame at a speed of between 50 and 400 mm/s, a terahertz radiation being generated by the terahertz sensor, reflections in the form of echoes being produced at the material boundaries in the tyre component, at least one material layer thickness (10, 11, 12) of the respective material layer in the tyre component being determined by the transit times of the echoes determined by the terahertz sensor, f) continuously evaluating the received measurement signals by software and monitoring the material layer thickness (10, 11, 12) of the respective material layer of the tyre component, the determined material layer thickness (10, 11, 12) of the respective material layer being compared in each case with a prescribed material layer thickness (10, 11, 12) of the respective material layer, g) continuously carrying on with the production process for the tyre component as long as no deviation from a prescribed material layer thickness (10, 11, 12) of the respective material layer is detected. a) providing a tyre component by a device for producing tyre components, the tyre component being produced in the form of a material ply and as a continuous material, b) continuously conveying the tyre component along a conveying section, a terahertz sensor being arranged above and/or below the tyre component, the terahertz sensor being arranged on a frame, c) carrying out a continuous material layer thickness measurement on the tyre component, the terahertz sensor being moved back and forth transversely in relation to the conveying direction above the tyre component and the terahertz sensor thereby being moved on the frame at a speed of between 50 and 400 mm/s, a terahertz radiation being generated by the terahertz sensor, reflections in the form of echoes being produced at the material boundaries in the tyre component, at least one material layer thickness (10, 11, 12) of the respective material layer in the tyre component being determined by the transit times of the echoes determined by the terahertz sensor, f) continuously evaluating the received measurement signals by software and monitoring the material layer thickness (10, 11, 12) of the respective material layer of the tyre component, the determined material layer thickness (10, 11, 12) of the respective material layer being compared in each case with a prescribed material layer thickness (10, 11, 12) of the respective material layer, g) continuously carrying on with the production process for the tyre component as long as no deviation from a prescribed material layer thickness (10, 11, 12) of the respective material layer is detected.