The correct installation of the car seat is a problem that worries many parents and to which scientists are looking for pertinent and evidence-based answers.

Experts at Ohio State University of Medicine say that after the initial installation, many parents change the position of the car seat to get a better seat angle on the seat. This is why parents use various improvisations such as foam tubes, sponge or rolled towels to fill the gap between the seat base and the car seat.


  is the director at  Injury Biomechanics Research Center , within Ohio State University College of Medicine. He is the author of this article published in LiveScience’s Expert Voices: Op-Ed & Insights.


For parents, the car seat is a necessary item from day one. For first-time parents, it can be extremely difficult to choose the best car seat model. The purchase decision is often influenced by price, safety features, and for some parents the closure is important.

In the United States, all car seats on the market comply with federal safety standards, so any new car seat is technically safe. But what many parents do not know is that some seats are not the best safe choices for each type of car.


A new study by John Bolte of Ohio State University College of Medicine shows that not all car seats fit all car models. Vaults suggest that measurements should be made in the car before purchasing the seat.

 John Bolde

Because there are so many differences between car seats, car seat manufacturers need parents to evaluate each of their particular situations. Previous studies have shown that between 73 and 90% of car seats are installed incorrectly, in some cases there are installation errors because there is an incompatibility between the car seat and the car.

Sometimes car seat manufacturers recommend making changes to the seat for a more correct installation in the car, such as putting on a rolled towel, a foam roller or sponge. Many parents wonder if using an “after-market” product, that is, a product that was not manufactured by the car manufacturer, is really safe.

As long as the parent can obtain the correct angle of inclination, the installation also remaining firm (without moving the seat more than 2.5 cm from the point of attachment), then the chair should behave in case of impact as it was created.

The big problem with after-market products such as towels or foam rolls is that by using them, all the responsibility is transferred to the consumer (parent) and that not all parents will correctly position these improvisations. Buying a seat that fits the car well from the beginning and that installs some is a greater chance that this seat will be used correctly every time.

This is why a firm installation is so important: most injuries to children following road accidents are the result of a collision between the child’s body and a hard surface inside the vehicle. A too loose installation allows the child’s head, arms and legs not to remain tight in the seat frame, but to hit the car doors, the center console or the front seats. A firm, correct installation keeps the child’s body and extremities protected in the car seat cover.

Prof. John Bold with his team members at Ohio State University College of Medicine and colleagues at Center for Child Injury Prevention Studies at the Pediatric Hospital of Philadelphia, studied the compatibility between different types of cars and car seats. In an effort to create a set of guides for parents, grandparents and others involved in purchasing a car seat, researcher Julie Bing and a team of students studied the dimensions of 54 types of vehicles and 59 models of car seats sold on the market. and identified the most common causes of incompatibility. Data from 3186 car / vehicle seat combinations were analyzed.

The research team found that in terms of the angle between the seat base and the car seat for Rear-Facing seats, 43.6% of the combinations were unacceptable. This angle is actually the space between the base of the seat and the car seat. The team of researchers found that the angle can vary by 15 degrees in various car seat combinations. The inclination of the seat is extremely important because it determines the angle in which a Rear-Facing car seat sits.

Julie Bing

If a car has a very sharp tilt angle of the seat, the parent will certainly have difficulty installing it below the tilt angle recommended by the manufacturer. Most car seats are built so that the child’s head has an inclination between 30 and 45 degrees from the vertical. The 15-degree variation between the angles of the various car seats on the market means that many seats end up being installed in an incorrect position (outside that angle between 30 and 45 degrees recommended for positioning the child).

Any car seat sold on the market in the United States must have passed some tests required by federal law Car seat manufacturers have obtained these certifications by testing these seats installed at the correct installation angle. Any deviation from this angle can result in a risk of injury to the child. These needles mean that parents may have difficulty installing the car seat on the seat so that it is perfectly fitted.

Before buying a car seat it is very important to measure the car. Pay attention to the angle of inclination of the rear seat, its width and the position of the headrest of the front seat. If the front seat head restraint has a certain position and your seat is high, this seat will not be able to be mounted correctly because the head restraint will prevent this.

It is very important for parents to make sure that the seat base aligns perfectly with the car seat. Parents should pay attention to the thick foam layer of the car seat. Usually, the foam of the seat can be impregnated at the bottom so that the base of the seat can align with the seat, but this is not always possible.

This article was originally published in the journal Live Science , > and Children’s Car Sfaety reproduced the content of this article, all the conclusions belonging to the authors of the study.

Read more about the installation problems frequently encountered in practice in the Auto Safety Information Center section.