The Physics Behind Tipping Trailers: Why Stability Matters

At STAS, safety is more than a feature—it's at the heart of how we design our trailers.
When tipping a fully loaded trailer, even the smallest imbalance can have serious consequences. That’s why we focus on two key pillars:

• Maximizing safety margins through smart engineering, premium materials, and extensive testing

• Educating operators so they understand not just the theory, but how to act in real-world conditions

This blog post dives into the physics of tipping trailers, starting with a fundamental concept: stability.

What is stability, really?

Stability comes down to weight distribution—specifically, the relationship between an object’s center of gravity and its base of support.

The center of gravity is the balance point of an object—where its weight is evenly distributed.
The base of support is the area beneath the object that supports its weight.

An object is stable when its center of gravity is above its base of support.
If the center of gravity shifts outside that base, it tips over.

Example: tipping points illustrated

• Balanced: Center of gravity is centered—maximum stability

• Less stable: Still within base, but shifting—risk increasing

• Tipped: Center of gravity has moved beyond the base—object falls

What happens when a trailer tips?

When a trailer tips, its center of gravity moves in two directions:

• Upward

• Rearward

Let’s look at what this means in practice.

1. Rearward shift: more load on rear axles

During tipping, if the load doesn't start sliding out right away (worst-case scenario), the weight shifts rearward.

• Front support = kingpin (truck connection)

• Rear support = center of axle tridem (air suspension system)

Load shift example:

• Before tipping:

  • Kingpin = 14 tonnes

  • Axle tridem = 24 tonnes

• During tipping:

  • Kingpin = 4 tonnes

  • Axle tridem = 34 tonnes

Why this matters:

• The rear axle suddenly carries up to 40% more weight

• Ground that’s “strong enough to drive on” might not be safe to tip on

• Tires, suspension, and axles operate near their technical limits

2. Upward shift: less margin for error

As the trailer rises, the center of gravity moves higher. Theoretically, this doesn’t change how weight is distributed—if the ground is perfectly level.

But no surface is ever completely flat.

On uneven ground:

• A raised center of gravity amplifies even small inclinations

• The safety margin shrinks dramatically

• Tipping becomes much riskier

Questions about safe tipping practices or trailer stability?

Our team is happy to help.