A pneumatic tire configured to rotate about an axis of rotation (AXR), the tire comprising - a tread comprising a first tread area portion , the tread being configured to form a contact with a surface when the tire is used, wherein an area of said contact of the tread with the surface forms a contact patch having a leading edge and a trailing edge , - a power source , - a transmission device, - an accelerometer arranged between the first tread area portion and the axis of rotation (AXR), and - a control unit configured to operate in a power saving mode and a normal mode, wherein - in said normal mode the control unit is configured to measure acceleration by the accelerometer , and characterized in that - in the power saving mode the control unit is configured to save power by not measuring acceleration by the accelerometer, wherein - a contact of the first tread area portion with the surface is detected by sensing the acceleration by said accelerometer , - the time required for the tire to make one revolution is determined, - the control unit is configured to switch from the normal mode to the power saving mode after a detection that the first tread area portion is on the contact patch , preferably on the trailing edge of the contact patch, and - the control unit is configured to switch from the power saving mode to the normal mode when a first specified time depending on the rotation speed of the tire, such as between 0.10 and 0.99 times the time required for the tire to make one revolution, has elapsed since said detection that the first tread area portion is on the contact patch , preferably on the trailing edge of the contact patch, in order to detect the leading edge and/or the trailing edge of the contact patch. - a tread comprising a first tread area portion , the tread being configured to form a contact with a surface when the tire is used, wherein an area of said contact of the tread with the surface forms a contact patch having a leading edge and a trailing edge , - a power source , - a transmission device, - an accelerometer arranged between the first tread area portion and the axis of rotation (AXR), and - a control unit configured to operate in a power saving mode and a normal mode, wherein - in said normal mode the control unit is configured to measure acceleration by the accelerometer , and characterized in that - in the power saving mode the control unit is configured to save power by not measuring acceleration by the accelerometer, wherein - in said normal mode the control unit is configured to measure acceleration by the accelerometer , and characterized in that - in the power saving mode the control unit is configured to save power by not measuring acceleration by the accelerometer, wherein - a contact of the first tread area portion with the surface is detected by sensing the acceleration by said accelerometer , - the time required for the tire to make one revolution is determined, - the control unit is configured to switch from the normal mode to the power saving mode after a detection that the first tread area portion is on the contact patch , preferably on the trailing edge of the contact patch, and - the control unit is configured to switch from the power saving mode to the normal mode when a first specified time depending on the rotation speed of the tire, such as between 0.10 and 0.99 times the time required for the tire to make one revolution, has elapsed since said detection that the first tread area portion is on the contact patch , preferably on the trailing edge of the contact patch, in order to detect the leading edge and/or the trailing edge of the contact patch. <EOS>