Why do tire manufacturers recommend inflating and then deflating tubes in new tires?

The correct rationale behind the recommendation for inflating and then deflating tubes in new tires is primarily to position the tube correctly inside the tire. When a tire is being mounted, the tube is initially deflated to facilitate easy insertion. Upon inflating the tube, it expands and fills the available space, allowing it to seat properly against the tire's interior surface.

As the tube inflates, any folds or wrinkles within the tube are smoothed out, ensuring that it is positioned correctly without bunching up or being pinched between the tire and the wheel rim. This proper positioning is crucial to ensuring the even distribution of air pressure inside the tire and preventing potential damage or failure during operation.

Mixing the rubber compound, testing for leaks, or allowing for thermal expansion are considerations that do not directly relate to this specific practice of inflating and deflating a new tire tube. Instead, the focus is on achieving the correct placement and orientation of the tube within the tire, which is essential for safe and effective tire performance.