Method for estimating a relative motion of vehicle body portions with respect to each other along a road segment having a length, wherein said length corresponds at least to a plurality of tire rotations, the method comprising: a) associating a respective monitoring unit to at least two tires of a vehicle, said monitoring units comprising at least one respective sensing element adapted to measure at least one quantity descriptive of a respective deformation of said tires; b) fitting said at least two tires to a respective wheel of said vehicle and operating said vehicle so as to cause rotation of said at least two tires on a rolling surface along said road segment wherein, due to said fitting and operating, said at least two tires are deformed so as to form a respective contact area between each of said at least two tires and said rolling surface; c) for each of said at least two tires, measuring said quantity at least during respective passages of said respective monitoring units in correspondence of said respective contact areas, d) for each of said respective passages, processing the measured quantity so as to obtain a value of a respective tire deformation undergone by each of said at least two tires in each of said respective passages, and to obtain, for each of said at least two tires, a respective plurality of values of said respective tire deformation over multiple tire rotations, said method characterized in that it comprises the further steps of: e) assembling said respective pluralities of values of said respective tire deformations so as to obtain, for each of said at least two tires, a respective curve representative of a deformation of said tires over multiple rotations along said road segment, f) comparing relative trends of said at least two curves so as to identify said relative motion of said respective vehicle body portions with respect to each other along said road segment. a) associating a respective monitoring unit to at least two tires of a vehicle, said monitoring units comprising at least one respective sensing element adapted to measure at least one quantity descriptive of a respective deformation of said tires; b) fitting said at least two tires to a respective wheel of said vehicle and operating said vehicle so as to cause rotation of said at least two tires on a rolling surface along said road segment wherein, due to said fitting and operating, said at least two tires are deformed so as to form a respective contact area between each of said at least two tires and said rolling surface; c) for each of said at least two tires, measuring said quantity at least during respective passages of said respective monitoring units in correspondence of said respective contact areas, d) for each of said respective passages, processing the measured quantity so as to obtain a value of a respective tire deformation undergone by each of said at least two tires in each of said respective passages, and to obtain, for each of said at least two tires, a respective plurality of values of said respective tire deformation over multiple tire rotations, said method characterized in that it comprises the further steps of: e) assembling said respective pluralities of values of said respective tire deformations so as to obtain, for each of said at least two tires, a respective curve representative of a deformation of said tires over multiple rotations along said road segment, f) comparing relative trends of said at least two curves so as to identify said relative motion of said respective vehicle body portions with respect to each other along said road segment.