A tie rod including a first tie rod part and a second tie rod part of plastic material, and a joint providing a length-adjustable connection between the first and second tie rod parts is provided. The joint includes a first and a second series of ribs made on the first and second tie rod parts, respectively. The first series of ribs is capable of engaging with the second series of ribs to define a relative longitudinal position of the first and second tie rod parts. The joint further includes a clip hinged to the first tie rod part and carrying the first series of ribs, the clip being foldable to snap onto the first tie rod part to lock an end of the second tie rod part within a seat of the first tie rod part.