Motivated by the persistently pursued weight reductions in a vehicle projected for a fuel efficiency competition, this thesis deals with designing new and lighter rims for the vehicle. The aim of the thesis is to design the rims with a carbon-fibre reinforced polymer, a lightweight composite material. A profound study on this kind of material is also presented, since it could be useful for lighten, subsequently, other parts of the vehicle. The thesis is based on a review of literature to acquire a theoretical framework. The design process and its validation is supported by finite element analyses. The preliminary design starts with a closed V profile, which appears to be a viable and adequate option for the application. The rim is divided into three parts, the contour and two sidewalls. By modelling and simulating the rim, the profile of each part is optimized and information about the stress´s state is acquired. Therefore the layered structure for the different parts are defined by taking the optimum proportions of the fibre's orientations into account. The parts are then simulated making use of a layered element which in the end validates the design. The reserve factors found are 1,67 for the contour and around 1,5 for the sidewalls, which indicates the good adjustment of the design between safety and performance. On the other hand, an estimation for the weight reduction is calculated, which achieves values around 17% on the better cases. With further work on the manufacturing process the design can in the end offer a reasonable saving of weight.