Will 33×12.5×20 Tires Fit a Stock F-150? The Definitive Guide

The short answer is generally yes, a 33×12.5×20 tire can fit a stock F-150, particularly on newer models (2009 and newer). However, “fit” doesn’t necessarily mean “fit perfectly without any rubbing or modifications.” Let’s dive deep into the nuances.

Understanding Tire Sizes and F-150 Compatibility

Decoding tire sizes is crucial. In 33×12.5×20, “33” represents the overall tire diameter in inches, “12.5” is the tire width in inches, and “20” is the wheel rim diameter in inches. The critical factors influencing whether these tires will work on your stock F-150 boil down to:

• Model Year: Newer F-150s (2009+) generally have more clearance than older models.

• Trim Level: Some trims, like the Raptor, come with a factory lift and wider fenders, making them more accommodating. Lower trims might require more consideration.

• Wheel Offset: This is absolutely critical. The offset dictates how far the wheel sits inward or outward relative to the hub. A negative offset will push the wheel outwards, potentially creating clearance issues with fenders, while a positive offset can cause rubbing on the suspension components. The stock wheel offset is designed for the factory tire size. Aftermarket wheels often have different offsets.

• Individual Truck Variation: Manufacturing tolerances exist. Even two identical F-150s might have slight differences in suspension and body panel alignment.

The Potential Issues with 33×12.5×20 Tires on a Stock F-150

Even if the tires technically fit, you might encounter these problems:

• Rubbing: The most common issue. The tires might rub against the upper control arms, the inner fender liners, or the mud flaps, particularly at full steering lock or when traversing uneven terrain.

• Reduced Turning Radius: Wider tires can limit the steering angle, decreasing your turning radius.

• Impact on Fuel Economy: Larger, heavier tires increase rolling resistance, leading to a noticeable drop in MPG.

• Speedometer Inaccuracy: Changing tire size alters the tire’s revolutions per mile. This can throw off your speedometer and odometer readings.

• Strain on Suspension Components: Heavier tires put more stress on the ball joints, wheel bearings, and other suspension parts, potentially shortening their lifespan.

Solutions and Mitigation Strategies

If you’re determined to run 33×12.5×20 tires on your stock F-150, here’s how to address the potential issues:

• Leveling Kit: A simple leveling kit (typically a 2-2.5 inch lift at the front) provides the necessary clearance to prevent rubbing. This is often the easiest and most cost-effective solution.

• Wheel Spacers: While not ideal due to potential safety concerns if improperly installed or maintained, wheel spacers can push the wheels outward, creating more clearance. Consult with a professional before considering wheel spacers.

• Trimming: In some cases, you can trim the inner fender liners or mud flaps to eliminate rubbing. Use caution and ensure you don’t compromise the structural integrity of these components.

• Adjusting Steering Stops: Some vehicles have adjustable steering stops that can limit the steering angle, preventing rubbing at full lock.

• Speedometer Calibration: Once you’ve installed the new tires, have your speedometer recalibrated to ensure accurate readings. A reputable tire shop can usually handle this.

Frequently Asked Questions (FAQs)

Here are some frequently asked questions to further clarify the topic:

1. What is the best way to determine if 33×12.5×20 tires will fit my specific F-150?

The absolute best way is to test fit them. Borrow a set of wheels and tires from a friend, or ask a tire shop if they can temporarily mount a set for test fitting. Observe closely for any rubbing or clearance issues while turning the steering wheel fully in both directions.

2. Do I need to re-gear my F-150 after installing 33-inch tires?

Re-gearing isn’t always necessary, but it’s highly recommended, especially if you frequently tow, haul heavy loads, or live in mountainous terrain. Larger tires effectively change your gear ratio, making the engine work harder. Re-gearing can restore performance and fuel economy.

3. Will 33×12.5×20 tires affect my F-150’s warranty?

Potentially. Installing aftermarket parts, including tires that deviate significantly from the factory size, could void the warranty on related components if a failure is directly attributed to the modification. Check your warranty documentation or consult with your Ford dealer.

4. What is the ideal wheel offset for running 33×12.5×20 tires on a leveled F-150?

This depends on the specific truck and the amount of leveling. Generally, an offset between +1mm and +25mm is a good starting point. Consult with a wheel and tire specialist for personalized recommendations.

5. How much does a leveling kit typically cost to install?

The cost varies depending on the type of kit and the labor rates in your area. A basic leveling kit can range from $100-$300, and installation typically costs between $200-$500.

6. Can I run 33×12.5×20 tires on my stock F-150 if I only drive on the street?

Even with strictly on-road driving, rubbing can still occur, particularly at full steering lock. A leveling kit or minor trimming is usually recommended.

7. Are there any specific brands of 33×12.5×20 tires that are known to fit better on stock F-150s?

Tire size variations exist between manufacturers, even within the same nominal size. Reading online reviews specific to your F-150 model year can offer insights into which brands tend to fit more easily.

8. What tools are needed to trim the inner fender liners?

A sharp utility knife, a heat gun (optional for shaping the plastic), and safety glasses are the basics. For a cleaner look, consider using a rotary tool with a cutting wheel.

9. Is it better to use wheel spacers or get wheels with a lower offset?

Getting wheels with the desired offset is generally the safer and more reliable option. Wheel spacers introduce additional stress and potential failure points.

10. What is the impact of tire load range on ride quality?

Higher load range tires (e.g., Load Range E) have stiffer sidewalls, resulting in a harsher ride, especially on a lighter vehicle like the F-150. Consider Load Range C or D tires for a more comfortable ride if you don’t need the extra load capacity.

11. Where can I find reliable information about F-150 tire and wheel fitment?

Online forums dedicated to F-150s are a great resource. Search for threads specific to your truck’s model year and trim level. Reputable tire retailers also offer fitment guides and expert advice.

12. What should I do if my tires are rubbing after installing a leveling kit?

Double-check that the leveling kit was installed correctly. If the rubbing persists, consider a smaller tire size, a more aggressive wheel offset (carefully), or further trimming of the fender liners. A body lift might also be needed as a last resort, but that is a more involved process.

By carefully considering these factors and taking appropriate precautions, you can likely enjoy the aggressive look and improved off-road capability of 33×12.5×20 tires on your F-150, even with minimal modifications. Remember to prioritize safety and consult with professionals when needed.