A tonneau cover that flaps violently at highway speeds is a common problem that can damage your cover and the contents of your truck bed. Thankfully, there are several solutions that can help stop a tonneau from flapping on the freeway.
What Causes Tonneau Cover Flapping?
Tonneau covers flap while driving for a few key reasons:
If the cover is not installed correctly per the manufacturer’s instructions, it can lead to a loose fit that allows wind to get underneath and create flapping. Key installation steps like tightening the cover evenly, aligning the rails, and securing any clamps or tension knobs properly are important to prevent flapping.
Wear and Tear
Over time, factors like UV exposure, temperature fluctuations, and normal use can degrade and stretch tonneau cover materials. This allows the cover to sag and flap more readily when driving at freeway speeds.
Some types of tonneau covers like soft roll-up covers are more prone to flapping than hard covers. The flexible vinyl material can flutter more easily. Upgrading to a tri-fold or retractable hard cover is one way to get a tighter, more wind-resistant tonneau.
The faster you drive, the more likely tonneau cover flapping becomes. The wind resistance increases exponentially at higher speeds, so flapping usually occurs more above 65+ mph.
How To Stop Tonneau Cover Flapping
If your tonneau cover already flaps or you want to prevent it from happening, here are the top solutions:
Tighten The Cover
Go over the entire cover and ensure every clamp, tension knob, and fastener is tightened properly per the installation guide. Focus on tightening evenly across the length of the cover. This removes any slack in the material to prevent whipping motions.
Adjust The Tension
Many retractable and roll-up covers have tension cables or knobs that can be tightened to keep the vinyl taut. Increase tension symmetrically on both sides so the cover stays centered on the bed. Be careful not to over-tighten.
Check The Installation
Make sure the cover is sitting flush with the bed rails and tailgate with no gaps. Realign the cover if needed. Verify all clamps/bows are correctly placed and bolts tightened to spec with the right torque.
Add Wind Flaps
Wind flaps and deflectors that attach to the front and rear of the truck bed can redirect airflow in a way that reduces tonneau flapping at high speeds.
Keep the vinyl cover surfaces conditioned with UV protectants and vinyl cleaners to maintain elasticity and prevent drying/cracking that leads to flapping.
Upgrade The Cover
If your current cover is worn out or a basic model, upgrading to a higher-end retractable or folding hard cover can provide a tighter seal and increased wind resistance. The sleek low-profile design also helps reduce flapping.
For roll-up covers, placing magnetic weights or sandbags along the edges can help weigh it down to prevent the vinyl from lifting up and fluttering at speed. Just don’t overload the cover.
Install Side Rail Seals
Sealing pads that affix into the bed rail gaps on either side of the tonneau cover can help close any openings that allow wind under the cover. This provides a flush air seal.
Adjust Rear Seals
Make sure the rear tonneau seals are resting correctly against the inside of the tailgate with no gaps. Adjust or replace the seals if they are loose, cracked, or misaligned.
Use Gutters/Drain Tubes
Slide-in gutter pieces fill the interior vinyl rail channels to prevent wind entry (and water buildup) that causes flapping. Just bear in mind drainage.
Lower Rear Window
Partially opening the rear cab window helps redirect wind over the tonneau cover instead of under it for less lifting force.
When To Consider A Tonneau Cover Upgrade
If your current tonneau cover flaps excessively or you’ve tried adjusting/reinforcing it with no success, it may be time for an upgrade. Here are signs to look for:
- The cover has become warped, stretched out, or has sagging corners
- Vinyl portions are cracked, ripped, or forever weathered
- It never sits flush and tight no matter how much you adjust it
- The cover lets in a lot of dust/debris and water
- It doesn’t latch or lock securely
- Makes loud slapping noises at freeway speeds
- Has broken components like hinges, snaps, or tension rods
Investing in a higher quality, tight-fitting tonneau like a tri-fold, retractable, or premium roll-up cover can make a huge difference in preventing flapping at highway speeds (and overall performance). Just make sure to verify compatibility with your truck’s bed size before purchasing.
Load Stabilization Tips To Reduce Flapping
How you load the truck bed can also impact tonneau cover flapping:
- Position heavier gear near the cab and avoid placing loads right behind the tailgate
- Secure lighter items with straps/cargo blocks to prevent sliding
- Get a bed divider/extender to keep items centered in the bed
- Use truck bed mats and rugs to provide more friction against cargo movement
- Keep the weight low and spread out evenly across the bed
- Avoid sudden braking/acceleration that shifts the cargo mass rearward
Keeping a balanced, stabilized load makes the truck more aerodynamic and reduces lift force on the tonneau cover while driving on the highway.
When To Remove The Tonneau Entirely
In some cases, the most straightforward solution is to take off the tonneau cover entirely when driving at higher speeds:
- Temporary fix before buying a replacement cover
- For optimal fuel economy on long highway trips
- When hauling oversized items that require an open bed
- If the cover is heavily damaged and no longer able to function
- If you don’t mind going coverless when freeway driving
Just remember to store the removed cover properly to prevent further damage.
Key Takeaways On Stopping Tonneau Flapping
In summary, a flapping tonneau cover is typically caused by installation error, wear and tear, wind resistance, and driving speed. Make sure to:
- Tighten all clamps, seals, and hardware evenly
- Use tonneau tension cables, straps, and weights
- Keep vinyl clean and conditioned against cracking
- Align the cover flush with no gaps or openings
- Upgrade to a snug-fitting retractable or tri-fold cover
- Load the truck bed intelligently to avoid shifting
- Add cab window deflectors or bed wind flaps
- Remove the cover entirely if needed for long highway trips
With the right adjustments and reinforcements, you can stop an annoying tonneau from flapping like a sail at freeway speeds. Just focus on tightening up any looseness while maintaining smart cargo placement and aerodynamic truck bed air flow.
Here are some other helpful questions and answers about tonneau covers:
How much do tonneau covers typically cost?
Tonneau cover prices range from $200 – $2000+ depending on the material, style, and truck bed size. Basic soft roll-up covers start around $200-400. Higher-end folding/retractable covers run $800-2000+.
How do I know if a tonneau will fit my truck?
The tonneau description will specify which truck bed size and model years it’s designed to fit. Measure your truck bed or look in the owner’s manual to verify the right size before ordering.
What are the main differences between hard and soft tonneau covers?
Soft covers use vinyl or canvas over aluminum frames. They roll or fold up for access. Hard covers are made of aluminum, fiberglass or ABS plastic. They fold, retract or lift up via hydraulic struts. Hard covers provide more durability and security.
How much can tonneau covers improve gas mileage?
By streamlining airflow over the bed, tonneaus can improve highway fuel economy by around 10-15% depending on speed. Retractable and rigid folding covers offer the best aerodynamic profiles.
What kind of warranty do most tonneau covers have?
Many come with a 3-5 year limited warranty on hardware, equipment failure, cracking, etc. Higher-end covers may offer lifetime warranties. Make sure to register after purchasing to activate coverage.
How difficult are tonneau covers to install?
Basic vinyl roll-ups allow for DIY install in 30-60 mins with clamps/bows. Folding hard covers take 1-2 hours with drilling. Retractables are hardest, often needing professional installation due to rail alignment.
What maintenance do tonneau covers need?
Keep vinyl conditioned and clean. Lubricate hinges every few months. Inspect seals and tension cables for wear. Tighten any loose clamps or hardware over time. Avoid direct pressure washer use.
Let me know if you need any clarification or have additional questions!