Case studies relating to child seats and children's age, height and weight have led to there being considerable confusion among the majority of parents when it comes to deciding which seat they should use for their children. The moment of greatest doubt is usually when it comes to deciding on the next model of child seat to purchase. Should the choice be made based on weight, height or age?
The basic premise to be clear on as far as a child's safety in the car is concerned is, above all, that they must travel using a seat appropriate for their height and physical characteristics. Weight is decisive in that any CRS will indicate the maximum weight that a child seat can support while maintaining its full capacity for protection. Once the maximum officially approved weight has been exceeded nobody can guarantee the seat's safety because no tests are carried out under those conditions.
Luckily, the new regulations and standards are planned and designed so that the determining factor for choosing a child seat is the child's height (here you can find answers to all your queries about the new standard ECE R129). This is because the interior of cars, and more specifically the design of seat belts, are intended for passengers at least 150 cm tall. Children and people below a height of 150 cm should use booster cushions to make it possible for their seat belt to fit perfectly and thus ensure a safe journey.
A child under 135 cm tall must travel in a child seat (we recommend one with a backrest) in such a way that the appropriate belt can be adjusted correctly and safely. In any case, weight is not what determines the choice of a child seat and, in point of fact, 36 kilos is the upper limit for officially approved child restraint systems in Europe. That does not necessarily mean that you cannot safely sit a child of this weight or even heavier in a booster seat.
Using it will not lead to it breaking, it is simply that the manufacturer will not take responsibility for the device or certify that the booster seat will offer optimum protection, as there is no current regulation to approve it and neither are the requisite laboratory tests carried out.
In the case we are concerned with, regarding children under 135 cm tall but yet who weigh over 36 kilos, they must use a booster seat (here are all the latest models of booster seats with a backrest). Using a booster seat enables the child to be securely fastened in by the seat belt and therefore travel more safely than without it. Also, if possible, it is best to choose a booster seat that can be tied or fastened to the car seat, so that the possibility of it slipping out from under the child is minimized.
In future, when only the ECE R129 standard will be valid, and if all seats approved under the previous standard are banned, all booster seats will be fitted with a backrest.