Currently in countries such as Brazil, the need of fuel consumption reduction and the consequent emission of air pollutants reduction are part of product development and vehicle homologation, implicating in weight reduction. In commercial vehicles, a great portion of the weight is related to its structure, in this case, chassis frames which are predominantly made of steel. This essay presents a material substitution of a chassis frame component from steel to aluminum resulting in weight reduction of around 40% with an increase in cost of also 40%. Chassis frames of 5Ton and a 3.5Ton trucks are the starting point of this study. Weight reduction potential were found during software simulation stages, especially on the following components: transmission crossmember, intermediate crossmember and single frame crossmember. Along the study, many geometry optimization iterations were done, but none of them satisfied the minimum weight reduction target set and, as a consequence, a material substitution study from steel to aluminum began. The study was split in two distinct phases: the first one involves material definition and its mechanical behavior, with material tests, compatibility with steel (the rest of the frame remains made out of steel) and with the current coating process. The second phase was related to the new geometry development throughout FEM (Finite Element Method) simulations, optimizations and fatigue life analysis, Once the structural part is virtually validated, a POC (proof of concept) to confirm the manufacturability and also the costs involved. Samples were sent to the final customer (OEM) which has tested the solution in accelerated durability tests validating it as a commercial product.