Why the Worst Tire Always Carries the Most Weight

[MikePhua]

The Hidden Burden of Trailer Tires
In the world of heavy hauling, trailers are often the unsung heroes—expected to endure punishing loads, uneven terrain, and long hours with minimal attention. Yet among all their components, tires are frequently overlooked until failure strikes. A recurring observation among seasoned operators is that the worst tire—the one with the slow leak, the aged sidewall, or the questionable tread—inevitably ends up bearing the most weight. This phenomenon isn’t just anecdotal; it’s rooted in physics, wear patterns, and the realities of field maintenance.
Understanding Load Distribution
Trailer load distribution is influenced by several factors:

• Suspension type (air ride vs. spring)
  
• Axle spacing and alignment
  
• Tire inflation pressure
  
• Frame flex and torsion
  

When a tire is underinflated or structurally compromised, it deforms more under load. This deformation causes adjacent tires to offload weight onto the weaker one, especially in multi-axle configurations. In air suspension systems, a malfunctioning leveling valve or deflated airbag can exacerbate this imbalance, forcing one tire to absorb disproportionate stress.
Terminology Annotation

• Airbag Suspension: A system using inflatable rubber bladders to support the trailer and adjust ride height.
  
• Leveling Valve: A pneumatic control device that regulates air pressure in suspension bags based on trailer height.
  
• Sidewall Separation: A failure mode where the tire’s outer casing detaches from the internal structure, often due to age or heat.
  

Field Case and Practical Insight
A hauler in Missouri recently prepared a trailer for a short 30-mile run. One tire, though technically new, had sat unused for years and showed signs of sidewall separation. With limited time and no mounted spare, the operator aired up the tire and hoped for the best. Predictably, the tire went flat before departure. After swapping it with another low-pressure spare, the issue persisted—a slow leak that threatened to derail the schedule.
This scenario is common in rural operations, where access to tire shops is limited and downtime is costly. The operator eventually sourced two used 11R22.5 tires from a local fleet for $50—a bargain that restored the trailer’s balance and reliability. The takeaway: proactive tire replacement, even with used inventory, can prevent cascading failures.
The Physics Behind Uneven Wear
Tires are dynamic load-bearing components. When one tire is compromised, its increased deflection alters the contact patch—the area where the tire meets the road. This change affects rolling resistance, heat generation, and tread wear. Over time, the compromised tire becomes a magnet for stress, accelerating its decline.
In multi-axle trailers, especially those with tandem or tridem setups, the weakest tire often ends up under the heaviest portion of the load due to suspension asymmetry. If one airbag fails to inflate, the adjacent tire becomes the fulcrum point, absorbing vertical force and lateral shear.
Preventative Strategies
To mitigate this issue, operators should adopt a structured maintenance routine:

• Weekly Pressure Checks: Maintain tire pressure within ±5% of manufacturer specs. For 11R22.5 tires, this typically means 95–105 psi.
  
• Visual Inspections: Look for bulges, cracks, and uneven tread wear. Sidewall damage is a leading cause of blowouts.
  
• Rotation Schedule: Rotate tires every 10,000 miles to equalize wear across axles.
  
• Suspension Audits: Inspect airbag integrity and leveling valve function monthly.
  
• Load Planning: Distribute cargo evenly and avoid overloading one side of the trailer.
  

Industry Trends and Data
According to the American Trucking Associations, tire-related failures account for nearly 20% of roadside breakdowns in commercial fleets. A 2022 study by Michelin revealed that underinflated tires reduce fuel efficiency by up to 3% and increase the risk of blowouts by 40%. With tire prices rising—averaging $350–$500 per unit for commercial grades—preventative care is more cost-effective than reactive replacement.
Anecdote from the Road
In 2021, a contractor hauling a loader across state lines experienced a suspension failure mid-trip. One airbag deflated, causing the trailer to lean and overload the rear-right tire. The tire overheated and delaminated, forcing an emergency unload on the shoulder. The operator later discovered that the leveling valve’s rubber connector had cracked—a $5 part that caused a $500 delay. This incident underscores the importance of inspecting small components that influence load distribution.
Conclusion
The worst tire always ends up with the most weight not by chance, but by a combination of mechanical imbalance, deferred maintenance, and reactive decision-making. Understanding the interplay between suspension systems, tire health, and load dynamics is essential for safe and efficient hauling. By investing in routine inspections, strategic replacements, and balanced loading, operators can break the cycle—and ensure that no tire bears more than its fair share.