A method of measuring a thickness of a tire tread, the method comprising the steps of: providing a tire tread, wherein the tire tread at least has a first tread layer formed of a first compound and a second tread layer formed of a second compound, wherein the electrical conductivity of the first compound is higher than the electrical conductivity of the second compound or wherein the first compound is an electrically conductive compound and the second compound is an electrically non-conductive compound; continuously conveying the tire tread; arranging a first terahertz sensor and a second terahertz sensor above and below the tire tread, respectively, wherein the first and second terahertz sensors (150, 155) are configured for emitting first and second radiation beams (152, 166), respectively, into the tire tread; receiving from the first radiation beam a first reflected radiation beam from a surface of the first tread layer and determining a first distance; receiving from the second radiation beam a second reflected radiation beam from an interface of the first and second tread layers (160, 130) and determining a second distance; receiving from the second radiation beam a third reflected radiation beam from a surface of the second tread layer and determining a third distance, and carrying out a material thickness measurement, preferably a continuous, repeated or periodical material thickness measurement during the continuous conveying of the tire tread, of the first and second tread layers (120, 160) by emitting the first and second radiation beams (152, 166) by the first and second terahertz sensors (150, 155), respectively, receiving the first, second, and third reflected radiation beams (162, 165, 164), characterized in that the first and second terahertz sensors (150, 155) are connected together at a fixed sensor distance or sensor height and that the first and second terahertz sensors (150, 155) are arranged colinear, and in that said carrying out a material thickness measurement determines a thickness of the first tread layer using said first, second and third distances (d1, d2, d3) and said fixed sensor distance or sensor height. providing a tire tread, wherein the tire tread at least has a first tread layer formed of a first compound and a second tread layer formed of a second compound, wherein the electrical conductivity of the first compound is higher than the electrical conductivity of the second compound or wherein the first compound is an electrically conductive compound and the second compound is an electrically non-conductive compound; continuously conveying the tire tread; arranging a first terahertz sensor and a second terahertz sensor above and below the tire tread, respectively, wherein the first and second terahertz sensors (150, 155) are configured for emitting first and second radiation beams (152, 166), respectively, into the tire tread; receiving from the first radiation beam a first reflected radiation beam from a surface of the first tread layer and determining a first distance; receiving from the second radiation beam a second reflected radiation beam from an interface of the first and second tread layers (160, 130) and determining a second distance; receiving from the second radiation beam a third reflected radiation beam from a surface of the second tread layer and determining a third distance, and carrying out a material thickness measurement, preferably a continuous, repeated or periodical material thickness measurement during the continuous conveying of the tire tread, of the first and second tread layers (120, 160) by emitting the first and second radiation beams (152, 166) by the first and second terahertz sensors (150, 155), respectively, receiving the first, second, and third reflected radiation beams (162, 165, 164), characterized in that the first and second terahertz sensors (150, 155) are connected together at a fixed sensor distance or sensor height and that the first and second terahertz sensors (150, 155) are arranged colinear, and in that said carrying out a material thickness measurement determines a thickness of the first tread layer using said first, second and third distances (d1, d2, d3) and said fixed sensor distance or sensor height.