The information in an owner's manual stating "do not use chains" could have various reasons depending on the specific vehicle and manufacturer. Here are some common reasons why an owner's manual might advise against using tire chains:

1. Clearances and Interference: Certain vehicles have limited space between the tire and other components within the wheel well. The use of tire chains could potentially cause interference or damage to these components, leading to safety hazards or vehicle malfunction.

2. Traction Control Systems: Some modern vehicles are equipped with traction control systems that rely on specific tire characteristics to operate effectively. The use of tire chains can interfere with these systems and affect their performance, potentially compromising safety.

3. Tire Size and Design: Tire chains are typically designed to fit specific tire sizes and profiles. If your vehicle's tires deviate significantly from the recommended size or design, the use of chains could cause fitment issues, resulting in poor performance, increased wear, or damage to the chains or tires.

4. Suspension and Handling: The addition of tire chains can alter the vehicle's handling characteristics, especially in vehicles with advanced suspension systems or specific handling requirements. The manual may advise against using chains to maintain optimal handling and stability.

It's important to respect the guidance provided in the owner's manual regarding the use of tire chains. If your vehicle's manual explicitly advises against using chains, it is generally recommended to explore alternative options for improving traction in winter conditions, such as snow tires, studded tires (where permitted), or other traction devices specifically recommended for your vehicle.