Ford E350 Dually Wheel Center Hole Size Guide: Front vs Rear Differences Explained

Here's the Deal

There appears to be some confusion about Ford dually wheels. Your 2001 Ford E350 Class C typically uses the same center bore size for all wheel positions, even though they share the same 8x6.5" (8x165.1mm) bolt pattern. All wheel positions typically use the same center bore size on the E350 platform, though hub configurations may vary. The spare wheel you purchased should fit all positions if it matches the E350 specifications, so the fitment issue may be due to an incorrect part or damaged components.

This isn't just a Ford quirk - it's actually an engineering design that optimizes wheel fitment for different axle configurations. The center bore, also called the pilot hole, must match the hub's pilot diameter for proper wheel centering and safe operation. Using a wheel with the wrong center bore can cause vibration, uneven tire wear, and potentially dangerous wheel wobble. You'll need to either find a front wheel with the correct larger center bore, or have your current spare wheel's center hole machined out to the proper diameter by a qualified machine shop.

What's Behind This

The confusion about Ford dually wheels stems from differences between Ford's various platforms. For the E350 van, all six positions typically use the same 8x6.5" (8x165.1mm) bolt pattern and similar load ratings, the hub configurations differ between front and rear axles. The E350 platform typically uses consistent hub pilot diameters across all positions. Check your specific vehicle's manufacturer specifications to confirm the exact requirements.

Here's what makes this particularly tricky for RV owners:

• Ford changed hub specifications multiple times between model years, so even "matching" years might have different requirements
• Aftermarket wheel manufacturers often produce wheels with generic center bores that may not match Ford's exact specifications
• Many tire shops and parts stores don't distinguish between front and rear dually wheels when selling spares
• The visual difference in center bore size is often subtle enough that it's not immediately obvious until you try to mount the wheel

The engineering reason behind different center bores relates to wheel centering and load distribution. The center bore ensures the wheel is perfectly centered on the hub before the lug nuts are tightened. This prevents the wheel studs from carrying centering loads - they should only handle clamping force. When the center bore is too small, the wheel can't seat properly against the hub face. When it's too large, the wheel can shift slightly during installation, potentially causing an off-center condition that leads to vibration and premature wear.

However, due to the different hub configurations between front and rear axles, the wheels are not interchangeable between all positions on the E350 van platform. This design approach is common across commercial vehicle platforms where reliability and load-carrying capacity take precedence over convenience.

Getting Started

WARNING: Always use proper jack stands and safety procedures when lifting and working under your RV. Never rely solely on a jack to support the vehicle weight.

Before you can solve your spare wheel dilemma, you'll need to measure the exact center bore dimensions on your existing wheels and confirm which type of spare you actually need. Start by safely lifting your RV and removing one wheel from each axle - front and rear - to get accurate measurements. You'll need a good caliper or measuring tape, and make sure to measure the actual hub pilot diameter as well as the wheel's center bore.

Here's how to properly measure and identify your wheel specifications:

1. Remove one front wheel and one rear dually wheel using proper jack stands and safety procedures
2. Clean any dirt or corrosion from the hub face and wheel mounting surfaces
3. Measure the hub pilot diameter on both front and rear axles using calipers - verify these measurements with Ford specifications
4. Measure the center bore of both wheels you removed
5. Check for any markings on the wheel that might indicate front/rear specific applications
6. Document the measurements and take photos for reference when shopping for replacements

While you have the wheels off, this is also a perfect time to inspect your existing wheels for any damage, corrosion, or wear issues. Look for cracks around the lug holes, bent rims, or any signs of stress. Pay particular attention to the rear dually wheels, as they're subjected to higher loads and more frequent mounting/dismounting cycles.

You'll also want to identify whether your spare needs to be a front-specific wheel or if a rear dually wheel will work for your intended use. Many RV owners prefer to carry a front wheel as a spare since front tire failures are often more critical for vehicle control and safety. However, statistically, rear tires experience more wear and damage due to their higher load carrying duties.

Making the Repair

You have several options to resolve your center bore mismatch, each with different cost implications and complexity levels. The most straightforward solution is to return or exchange your current spare for one with the correct center bore size. However, if you want to keep the wheel you purchased, or if finding the right wheel proves difficult, there are mechanical solutions available.

One option is having the center bore machined out, though this can weaken the wheel structure and void warranties. This precise operation requires proper equipment and expertise, and should only be done after consulting manufacturer specifications. Here's what's involved in this process:

• Find a machine shop with experience in wheel modification and the proper boring equipment
• Expect to pay between $50-150 per wheel depending on your local labor rates
• The process typically takes 1-2 hours per wheel once they have it in the machine
• Make sure they understand the critical importance of maintaining perfect concentricity during boring
• Request that they deburr and smooth the finished bore to prevent any sharp edges

Another option is using hub-centric rings, though this is generally not recommended for heavy-duty applications like your Class C RV. These plastic or aluminum rings fill the gap between a larger wheel bore and smaller hub, but they're designed for lighter passenger vehicles and may not provide adequate support for your RV's weight and driving conditions.

If you decide to shop for a replacement spare instead, here are the key specifications you'll need:

• Bolt pattern: 8x170mm (which you already confirmed matches)
• Center bore: Measure your hub to get the exact diameter and verify with Ford specifications
• Load rating: Must meet or exceed your RV's requirements (check your door jamb sticker)
• Offset: Should match your existing wheels to maintain proper track width and suspension geometry
• Wheel diameter and width: Should match your existing setup unless you're planning a tire size change

When shopping, be specific about your application. Tell suppliers you need a front dually wheel for a 2001 Ford E350, not just "a dually wheel with 8x170 pattern." Many online retailers and local shops can look up the exact specifications for your vehicle year and model, which eliminates the guesswork.

Call in the Pros

While measuring and identifying wheel specifications is something most RV owners can handle, there are several aspects of this repair where professional help is worth the investment. A qualified tire shop or truck service center will have the tools and experience to quickly identify your exact wheel requirements and source the correct replacement.

Professional shops offer several advantages for this type of issue:

• Access to comprehensive wheel fitment databases that include center bore specifications
• Relationships with commercial wheel suppliers who stock Ford dually wheels
• Proper equipment for safely mounting and balancing heavy RV wheels
• Experience with hub-centric fitment issues and potential solutions
• Warranty coverage on parts and labor if problems arise

If you choose to have your existing wheel's center bore machined out, it's crucial to find a machine shop with experience in wheel modification. Not all shops have the proper boring bars or understand the precision required for this type of work. Ask potential shops about their experience with similar jobs and request to see examples of their wheel boring work.

For future reference, consider establishing a relationship with a commercial tire dealer who specializes in fleet and RV service. These businesses understand the unique requirements of larger vehicles and typically stock or can quickly source the specific wheels and tires your E350 requires. Many offer road service as well, which can be invaluable if you experience a tire failure while traveling.

Don't overlook Ford dealerships with commercial vehicle departments. While they might be more expensive than independent shops, they have direct access to OEM wheels and can guarantee proper fitment. This might be worth the extra cost for critical components like wheels where safety is paramount.

Finally, consider joining online forums specific to Ford Class C RVs or E350-based motorhomes. Other owners often share sources for hard-to-find parts and can provide specific part numbers and vendor recommendations based on their own experiences with similar repairs. When measuring your specific hub and wheel dimensions, always verify these measurements against Ford's official specifications to ensure accuracy before making any modifications or purchases.