Will They Fit On A Dually Pickup Truck

Will They Fit On A Dually Pickup Truck cars.truckstrend.com

The mighty dually pickup truck, with its distinctive dual rear wheels, is a symbol of immense power, stability, and towing capability. Designed to handle heavy loads and conquer the toughest tasks, these workhorses are a favorite among contractors, RV enthusiasts, and anyone needing serious hauling capacity. However, with their unique design comes a critical question for owners looking to customize, upgrade, or simply understand their vehicle better: "Will they fit?"

This seemingly simple question encompasses a wide array of considerations, from oversized tires and aftermarket wheels to slide-in campers, fifth-wheel hitches, and various accessories. Unlike single-rear-wheel trucks, the dually’s dual tire setup and wider rear fenders introduce specific challenges and limitations that demand careful planning and precise measurements. Getting it wrong can lead to costly damage, compromised safety, and even legal issues. This comprehensive guide will delve into the intricacies of dually fitment, providing you with the knowledge and practical advice needed to ensure everything fits perfectly on your heavy-duty machine.

Will They Fit On A Dually Pickup Truck

Understanding the Dually’s Unique Design and Its Implications

Before diving into specific items, it’s crucial to understand why duallies pose unique fitment challenges. Their design is centered around maximizing stability and load distribution, which directly impacts what can and cannot fit.

• Dual Rear Wheels (DRW): The most obvious feature. Two tires on each side of the rear axle mean a significantly wider overall footprint. This width is the primary factor limiting tire size and wheel offset.
• Wider Rear Fenders/Flares: To accommodate the dual tires, duallies come equipped with extended rear fenders or fender flares that protrude significantly from the truck’s body. These provide necessary coverage but also define the outer boundary for anything you want to install, especially tires.
• Axle Width and Hubs: Dually axles are typically wider than their single-rear-wheel counterparts to allow for proper spacing between the dual tires. The hubs are also designed to accommodate the unique mounting of two wheels per side.
• Suspension Geometry: While similar to SRW trucks, the suspension is often beefed up to handle heavier loads. Modifications like lift kits must consider the dual-wheel setup to maintain proper alignment and prevent rubbing.
• Critical Tire Spacing: For dual tires, maintaining adequate space between the inner and outer tires is paramount. This gap allows for heat dissipation, prevents rubbing under load or cornering, and ensures proper tire wear.

The Primary "They": Tires and Wheels

When dually owners ask "Will they fit?", they are most often referring to larger, aftermarket tires and wheels. Upgrading tires is popular for aesthetic reasons, improved off-road capability, or increased load capacity. However, it’s where most fitment issues arise.

Tire Size Nomenclature Explained

Understanding tire sizes is the first step. You’ll typically see two formats:

• Metric (e.g., LT275/70R18):
  • 275: Tread width in millimeters.
  • 70: Aspect ratio (sidewall height as a percentage of width).

  

  • R: Radial construction.
  • 18: Wheel diameter in inches.
• Flotation (e.g., 35×12.50R20):
  • 35: Overall tire diameter in inches.
  • 12.50: Tread width in inches.
  • R: Radial construction.
  • 20: Wheel diameter in inches.

Key Factors Affecting Tire Fitment on a Dually

1. Overall Diameter: A taller tire (larger diameter) can rub against the inner fender wells, suspension components, or even the front bumper/fender when turning.
2. Tread Width: A wider tire is the biggest challenge for duallies. It directly impacts the crucial gap between the inner and outer rear tires. Too wide, and they’ll rub against each other, leading to rapid wear, heat buildup, and potential blowouts. It also dictates whether the tire stays within the confines of the dually fender.
3. Wheel Offset and Backspacing: This is critical for duallies.
   • Offset: The distance from the wheel’s mounting surface to the wheel’s centerline.
     • Positive Offset: The mounting surface is closer to the outside of the wheel (pushes the wheel/tire inward).
     • Negative Offset: The mounting surface is closer to the inside of the wheel (pushes the wheel/tire outward).
   • Backspacing: The distance from the mounting surface to the inner edge of the wheel.
   • For duallies, the inner rear wheel needs a specific positive offset or backspacing to ensure it clears suspension components and creates enough space for the outer wheel. The outer rear wheel often requires a different, usually less positive or even negative, offset to push it out and maintain the crucial gap with the inner wheel and clear the fender. Aftermarket dually wheels are typically designed with specific offsets for inner and outer positions.

The Critical Rear Tire Gap

This cannot be overstressed. You need a minimum of 1.5 to 2 inches (38-50mm) of clear space between the sidewalls of the inner and outer rear tires. This prevents them from rubbing when the truck flexes, turns, or carries a heavy load. Rubbing generates immense heat, rapidly degrades tire integrity, and is a major safety hazard.

Beyond Tires: Other "Fits" to Consider

While tires are paramount, "Will they fit?" also applies to other significant additions.

• Truck Campers:
  • Weight Distribution: A dually is ideal for heavy campers, but the camper’s center of gravity must align with the truck’s design.
  • Overhang: Ensure the camper doesn’t extend too far past the rear bumper, affecting departure angle or legal limits.
  • Clearance: Check for clearance with the cab (especially on short-bed duallies with large campers), and ensure no interference with the dual rear fenders. Some campers require specific dually-friendly designs or extensions.
• Fifth-Wheel Hitches and Trailers:
  • Bed Clearance: Ensure the fifth-wheel hitch provides enough vertical clearance (typically 6 inches) between the trailer’s kingpin box and the truck’s bed rails, especially when going over uneven terrain.
  • Turning Radius: The combination of a wide dually and a fifth-wheel trailer can lead to cab-to-trailer contact during tight turns. Slider hitches are often recommended for short-bed duallies to prevent this.
  • Weight Ratings: Always adhere to the truck’s Gross Vehicle Weight Rating (GVWR), Gross Combined Weight Rating (GCWR), and Gross Axle Weight Ratings (GAWRs).
• Toolboxes and Bed Accessories:
  • Bed Length: Ensure the accessory fits within the bed length without interfering with other equipment (like a fifth-wheel hitch).
  • Wheel Well Clearance: Some larger toolboxes or bed systems might need to clear the inner wheel wells.
  • Tie-Down Points: Confirm compatibility with existing tie-down points or find suitable mounting solutions.

Measuring and Calculating for Proper Fit

Accurate measurement is your best friend. Don’t guess.

1. Measure Your Current Setup:
   • Existing Tire Dimensions: Use a tape measure to get actual diameter and width.
   • Fender Clearance: Measure the distance from the top of your tire to the inside of your fender well.
   • Front Wheel Well Clearance: Turn your steering wheel lock-to-lock and measure clearance at various points.
   • Rear Tire Spacing: Crucial for duallies – measure the exact gap between your inner and outer rear tires.
   • Wheel Backspacing/Offset: If you have the wheels off, measure from the mounting surface to the inner lip of the wheel for backspacing.
2. Use Online Calculators: Many tire and wheel websites offer calculators that compare new tire sizes to old ones, showing changes in diameter, width, and how they relate to offset.
3. Understand Wheel Specs:
   • Bolt Pattern: Must match your truck (e.g., 8x170mm for Ford, 8x200mm for Ram, 8×165.1mm/8×6.5" for older GM/Ram).
   • Hub Bore: The center hole of the wheel must be large enough to clear your truck’s hub.
   • Load Rating: Crucial for duallies. Ensure the new wheels and tires have a combined load rating that exceeds your truck’s GAWR for both axles.

Modifications for Fitment

Sometimes, a direct bolt-on isn’t possible, and modifications are needed.

• Lift Kits/Leveling Kits:
  • Purpose: Increase ground clearance and create space for larger tires.
  • Considerations: Affects suspension geometry, steering angles, and potentially ride quality. Ensure the kit is designed for a dually and maintains proper alignment for dual tires.
  • Types: Body lifts (aesthetic, no suspension change) vs. Suspension lifts (coil spacers, new shocks, leaf springs, etc.).
• Fender Flares/Wheel Well Trimming:
  • Purpose: Provide additional clearance for wider tires or meet legal requirements for tire coverage.
  • Considerations: Trimming is irreversible and can impact resale value. Aftermarket fender flares are a common solution for dually owners running wider tires that extend beyond the stock fenders.
• Wheel Spacers/Adapters:
  • Purpose: Push wheels further out from the hub, primarily used to correct offset issues or adapt different bolt patterns.
  • Cautions: Use high-quality, hub-centric spacers specifically designed for heavy-duty applications. Poor quality or improper installation can lead to wheel vibration, stud failure, and catastrophic wheel separation, especially under load. Avoid them for the rear duals if possible; proper offset wheels are always preferred.
• Custom Beds/Fenders: For extreme builds or highly specialized applications, custom beds or wider fenders might be fabricated, but this is a significant undertaking.

Important Considerations & Potential Challenges

Ignoring fitment details can lead to severe consequences.

• Safety:
  • Tire Rubbing: Leads to premature tire wear, sidewall damage, heat buildup, and potential blowouts.
  • Component Interference: Rubbing on suspension, steering, or brake components can cause damage and compromise control.
  • Overloading: Ensure new components maintain or exceed original load ratings, especially tires and wheels.
• Legality:
  • Tire Coverage Laws: Many states require tires to be fully covered by fenders. If your new tires stick out, you might need wider fender flares.
  • Height Restrictions: Some states have limits on vehicle height or bumper height.
• Warranty Implications: Modifications can void parts of your vehicle’s factory warranty. Consult your dealer.
• Performance Impact:
  • Gearing: Larger tires effectively change your final drive ratio, reducing torque and potentially impacting towing performance and acceleration. Re-gearing the axles might be necessary.
  • Fuel Economy: Larger, heavier, and more aggressive tires increase rolling resistance and unsprung weight, significantly reducing fuel efficiency.
  • Braking: Increased unsprung weight and rotating mass can negatively impact braking performance.
  • Speedometer/Odometer Accuracy: Larger tires will cause your speedometer to read low and odometer to under-report mileage. This can usually be corrected with a tuner or dealership recalibration.
• Towing/Hauling Capacity: Ensure modifications do not compromise your truck’s advertised towing or payload capacities. Often, larger tires reduce effective capacity if gearing isn’t changed.

Tips for Success

1. Research Thoroughly: Don’t rely on guesswork. Use forums, manufacturer specifications, and online resources.
2. Consult Professionals: Talk to reputable tire shops, off-road specialists, or custom fabrication shops with experience in dually trucks.
3. Test Fit If Possible: If buying used wheels or tires, or if a shop offers it, a test fit is the best way to confirm clearance before committing.
4. Prioritize Safety: Never compromise safety for aesthetics or perceived performance. The consequences can be dire.
5. Start Small: If unsure, make incremental changes. A mild leveling kit and slightly larger tires are less likely to cause issues than a radical lift and massive tires.

Estimated Cost Considerations for Dually Fitment

Achieving the perfect fit on your dually can involve various components and services, each with an associated cost. Below is an estimated price range for common items and services related to dually fitment. Prices can vary significantly based on brand, quality, location, and specific vehicle model.

Item/Service Category	Description	Estimated Price Range (USD)	Notes
Aftermarket Tires	Larger diameter or wider tires, typically All-Terrain (A/T) or Mud-Terrain (M/T)	$300 – $800 per tire	High-load rating required; price varies by size, brand, and type.
Aftermarket Wheels	Dually-specific wheels (inner/outer) with correct offset/backspacing	$250 – $600 per wheel	Designed for dually spacing; often sold in sets of 6.
Lift Kit (Suspension)	2" – 6" suspension lift, includes shocks, springs, control arms, etc.	$800 – $4,000+	Varies by lift height, brand, and components. Installation extra.
Leveling Kit	Front-end leveling (spacers or torsion keys) to reduce factory rake	$100 – $300	Typically for front only; simpler to install.
Installation (Lift/Leveling)	Labor cost for professional installation of lift or leveling kit	$400 – $1,500+	Depends on kit complexity and shop labor rates. Alignment usually extra.
Alignment (Post-Lift)	Essential after suspension modifications to correct steering and tire wear	$100 – $250	Critical for safety and tire longevity.
Fender Flares	Aftermarket flares to cover wider tires and meet legal requirements	$200 – $800+ (set)	Aesthetic and functional; various styles and materials.
Wheel Spacers/Adapters	Used to push wheels out or change bolt pattern (use with caution for duallies)	$100 – $300 (per pair)	High-quality, hub-centric recommended. Avoid for rear duals if possible.
Speedometer Recalibration	Adjusting speedometer/odometer for larger tires	$50 – $300	Can be done with a programmer/tuner or by a dealership.
Re-gearing Axles	Changing differential gears to compensate for larger tires (improves performance, fuel economy)	$1,500 – $3,000+ (per axle)	Significant cost; often requires professional installation and setup.
Truck Camper Dually Adaptations	Specific camper modifications or accessories to clear dually fenders (e.g., extensions)	$500 – $2,000+	Varies greatly by camper model and required adjustments.
Fifth-Wheel Slider Hitch	For short-bed duallies, allows hitch to slide back for turning clearance	$800 – $2,000+	Essential to prevent cab/trailer contact on tight turns.

Frequently Asked Questions (FAQ)

Q1: Can I put regular (SRW) wheels on my dually?
A1: No, not safely or correctly. Dually wheels have specific offsets and load ratings designed for the dual-wheel setup. Using SRW wheels will result in incorrect tire spacing, potential rubbing, and insufficient load capacity, leading to dangerous situations.

Q2: What’s the biggest tire size I can fit on my dually without a lift?
A2: This varies significantly by truck make, model, and year. Generally, you might be able to go one or two sizes larger (e.g., from a 33-inch stock tire to a 34-inch or small 35-inch) if the tire isn’t too wide and you maintain the critical rear tire gap. Always measure and consult forums specific to your truck model.

Q3: How much space do I need between my rear dual tires?
A3: A minimum of 1.5 to 2 inches (38-50mm) of clear space between the sidewalls is crucial. This prevents rubbing under load, during turns, or over bumps, which can cause tire failure due to heat and friction.

Q4: Will a lift kit affect my dually’s towing capacity?
A4: A properly installed, high-quality lift kit designed for duallies should not directly reduce the structural towing capacity of the truck’s frame. However, larger tires (which often accompany lift kits) can effectively change your gearing, leading to reduced towing performance and increased strain on the drivetrain. Re-gearing is often recommended for heavy towing with larger tires.

Q5: Are wheel spacers safe on a dually?
A5: While often used, wheel spacers on duallies are generally discouraged, especially for the rear duals. They add more points of failure and can put extra stress on wheel studs and bearings, particularly under heavy loads. If you must use them, opt for high-quality, hub-centric, bolt-on adapters specifically rated for heavy-duty applications, and ensure professional installation and regular inspection. It’s always safer and more reliable to use wheels with the correct offset.

Q6: My new tires rub slightly when I turn. What can I do?
A6: Slight rubbing can sometimes be addressed with minor trimming of plastic inner fender liners or, in some cases, adjusting steering stops. However, if the rubbing is significant or involves metal components, it indicates a major fitment issue that needs a more substantial solution like a lift, different wheels, or smaller tires. Don’t ignore rubbing, as it can be dangerous.

Conclusion

The question "Will they fit on a dually pickup truck?" is more complex than it appears, requiring a thorough understanding of the vehicle’s unique design and the specific dimensions of whatever "they" refers to. From the critical spacing between dual rear tires to the careful consideration of wheel offset, fender clearance, and the impact of modifications on performance and safety, every detail matters.

By meticulously measuring, researching, and, when necessary, consulting with experienced professionals, you can confidently customize your dually to meet your needs without compromising its legendary capability or your safety. Remember, a well-planned and properly executed fitment ensures your dually remains the powerful, reliable workhorse it was designed to be, ready to tackle any challenge you throw its way.