A tire comprising: a tread portion provided with a tread pattern, the tread pattern comprising a series of a number N of tread design units arranged repeatedly and circumferentially of the tire in a sequence, the tread design units having at least two different circumferential lengths, characterised in that, when viewing the tread design units as the number N of pulses having magnitudes proportional to the respective circumferential lengths of the tread design units, and defining a pulse train such that the number N of the pulses are arranged in the same sequence as the tread design units at intervals which are defined by the circumferential lengths of the corresponding tread design units expressed in term of a ratio to one of said at least two different circumferential lengths, and further expressing magnitudes of the pulses by the respective circumferential lengths in term of a ratio to the median value of said at least two different circumferential lengths, the average of the magnitudes of the pulses corresponding to said at least two different circumferential lengths is limited to 1.00, a maximum value Fmax of amplitude F(k) of k-th order, k = 1 to 2N, of frequencies obtained by Fourier transforming said pulse train with the following formula is limited to satisfy the following condition: Fmax <= 4.52 - 0.0125 N, F k = 10 k 2 c k 2 + d k 2 c k = ∑ j = 1 N p j ⋅ sin 2 πk l ⋅ X j d k = ∑ j = 1 N p j ⋅ cos 2 πk l ⋅ X j wherein P(j) is the magnitude of the j-th pulse, j = 1 to N, counted from a beginning of the pulse train, x(j) is the position of the j-th pulse from the beginning of the pulse train, and 1 is a circumference length parameter equal to the sum of said ratios expressing the circumferential lengths of all the tread design units in a series, and the amplitudes F(k) of every two of the adjacent orders (k) and (k+1) are limited so as not to satisfy a condition that both of the amplitudes F(k) and F(k+1) have values of 2/3 or more times said maximum value Fmax. a tread portion provided with a tread pattern, the tread pattern comprising a series of a number N of tread design units arranged repeatedly and circumferentially of the tire in a sequence, the tread design units having at least two different circumferential lengths, characterised in that, when viewing the tread design units as the number N of pulses having magnitudes proportional to the respective circumferential lengths of the tread design units, and defining a pulse train such that the number N of the pulses are arranged in the same sequence as the tread design units at intervals which are defined by the circumferential lengths of the corresponding tread design units expressed in term of a ratio to one of said at least two different circumferential lengths, and further expressing magnitudes of the pulses by the respective circumferential lengths in term of a ratio to the median value of said at least two different circumferential lengths, the average of the magnitudes of the pulses corresponding to said at least two different circumferential lengths is limited to 1.00, a maximum value Fmax of amplitude F(k) of k-th order, k = 1 to 2N, of frequencies obtained by Fourier transforming said pulse train with the following formula is limited to satisfy the following condition: Fmax <= 4.52 - 0.0125 N, F k = 10 k 2 c k 2 + d k 2 c k = ∑ j = 1 N p j ⋅ sin 2 πk l ⋅ X j d k = ∑ j = 1 N p j ⋅ cos 2 πk l ⋅ X j wherein P(j) is the magnitude of the j-th pulse, j = 1 to N, counted from a beginning of the pulse train, x(j) is the position of the j-th pulse from the beginning of the pulse train, and 1 is a circumference length parameter equal to the sum of said ratios expressing the circumferential lengths of all the tread design units in a series, and the amplitudes F(k) of every two of the adjacent orders (k) and (k+1) are limited so as not to satisfy a condition that both of the amplitudes F(k) and F(k+1) have values of 2/3 or more times said maximum value Fmax. P(j) is the magnitude of the j-th pulse, j = 1 to N, counted from a beginning of the pulse train, x(j) is the position of the j-th pulse from the beginning of the pulse train, and 1 is a circumference length parameter equal to the sum of said ratios expressing the circumferential lengths of all the tread design units in a series, and the amplitudes F(k) of every two of the adjacent orders (k) and (k+1) are limited so as not to satisfy a condition that both of the amplitudes F(k) and F(k+1) have values of 2/3 or more times said maximum value Fmax.