Tire Sizing Fundamentals: What Every Salesperson Must Know

Introduction

Tire sizing is one of the most foundational—and most misunderstood—topics in our industry. Customers often show up unsure about what the numbers mean, and even experienced salespeople can stumble when switching between Metric, LT, and Flotation sizing.

This post breaks down the three major sizing systems, explains how they compare, and highlights what front-counter staff must know to guide customers with confidence.

1. Understanding Metric Sizing

Examples: 225/60R16, 205/55R17

What Metric Sizing Is

Metric (P-Metric and Euro-Metric) sizing is the most common format on passenger vehicles. It emphasizes comfort, fuel economy, and predictable handling.

• Width (mm) – Example: 225
• Aspect Ratio (%) – Example: 60
• Wheel Diameter (inches) – Example: 16

Where You’ll See It

• Sedans
• Crossovers
• Small and midsize SUVs
• Minivans

Key Points for Salespeople

• Not all metric sizes are equal—P-Metric and Euro-Metric carry different load capacities.
• These sizes are tied closely to OE ride quality and handling.
• Great for daily commuters, families, and anyone prioritizing comfort.

Sales Application

When a customer is unsure about sizing, start with their OE fitment. Metric sizing is the baseline for most modern vehicles and sets the stage for correct performance and comfort.

2. Understanding LT (Light Truck) Sizing

Examples: LT275/65R20, LT245/75R16

What LT Sizing Means

LT tires are built for higher load capacity, stronger construction, and heavier-duty work. They may look similar to metric sizing at a glance, but they perform very differently.

• Reinforced casing
• Higher PSI capability
• Heavier, more durable construction
• Often deeper tread

Where You’ll See It

• ¾-ton and 1-ton pickups
• Trucks used for towing
• Work trucks, service vehicles
• Farm, ranch, and commercial fleets

Key Points for Salespeople

• NEVER replace an LT-required tire with a P-Metric.
• Load Range (C, D, E, F) matters—match or exceed OE.
• Expect firmer ride; set customer expectations early.

Sales Application

Ask lifestyle and usage questions:

• “How often do you tow?”
• “What’s in your bed during a normal week?”

The right LT tire solves real problems—confidence, stability, safety, and durability.

3. Understanding Flotation Sizing

Examples: 33x12.50R20, 35x12.50R17, 31x10.50R15

What Flotation Sizing Means

Flotation sizes originate from off-road use. The goal is to “float” over softer terrain such as sand, mud, or deep snow.

• Overall Diameter (inches) – Example: 33
• Section Width (inches) – Example: 12.50
• Wheel Diameter (inches) – Example: 20

Where You’ll See It

• Lifted trucks
• Off-road builds
• Overlanding setups
• Sand and mud applications

Key Points for Salespeople

• Does not directly convert to metric—know how to compare diameter and width.
• Fitment depends on lift height, wheel offset, and fender clearance.
• Larger isn’t always better—bigger tires affect gearing, braking, and fuel economy.

Sales Application

Before selling “35s,” ask:

• “What lift do you have?”
• “What wheels?”
• “Daily driver or 80% off-road?”

This prevents rubbing issues, returns, and unhappy customers.

4. How They Compare

5. What Salespeople Need to Know to Sell These Correctly

A. Fitment Fundamentals

Your team must confidently recognize:

• OE sizing
• Load index & speed rating
• Wheel width, offset, and clearance
• Effects of upsizing or downsizing

B. Vehicle Use-Case Analysis

Every recommendation should start with:

• How the vehicle is used
• Towing or payload needs
• Highway vs. off-road percentages
• Desired ride quality & noise level

C. Clear Customer Communication

A salesperson who can explain tire sizing in simple terms builds instant credibility. Customers listen more closely when you translate numbers into benefits:

• Comfort
• Durability
• Capability
• Appearance
• Safety

Conclusion

Mastering the differences between Metric, LT, and Flotation sizing is essential for any tire salesperson. This knowledge prevents fitment issues, builds customer trust, and elevates your shop’s professionalism. When your staff understands how to connect a customer’s needs with the right sizing system, they don’t just sell tires—they deliver solutions.