A tonneau cover gasket serves a critical purpose – to create a tight seal between the truck bed and tonneau cover to protect cargo from weather and theft. This gasket forms a barrier against dust, rain, snow and more, keeping your truck bed contents clean and dry. But what specifically makes this gasket so important? Read on to learn all about the purpose and function of a tonneau cover gasket.
Why Do You Need A Gasket For Your Tonneau Cover?
A tonneau cover alone is not enough to fully seal and secure the truck bed. Even when closed, gaps may exist between the cover and bed due to minor inconsistencies in manufacturing and installation. Over time, a cover can also bend or warp slightly, enlarging these gaps.
Without a gasket, openings let in dust, humidity, rain leaks and more. Valuable cargo could get wet, dirty or even stolen through unsealed areas. A proper gasket eliminates gaps, enhancing protection against:
- Weather – Rain, snow, wind and dust are kept out. Your gear stays clean and dry.
- Theft – Gaps could allow access to cargo. The gasket blocks entry opportunities.
- Pests – Rodents or insects may crawl into unsealed spots. The gasket deters stowaways.
- Noise – Wind and road noise increase with openings. The gasket dampens sound.
- Mileage – Openings lower aerodynamics, decreasing MPG. The gasket improves air flow and fuel efficiency.
How Does A Tonneau Cover Gasket Create A Tight Seal?
This gasket sits between the cover and bed, filling any spaces or cracks. When you close the cover, the gasket compresses to create a tight, impenetrable barrier along the entire perimeter. It works similarly to weather stripping around doors and windows.
Made of dense rubber, foam or vinyl, the gasket regains its shape after opening the cover. The material is durable for long-lasting performance through all weather conditions. No matter how many times you open or close the cover, the gasket continues sealing out elements.
What Factors Determine Gasket Size And Shape?
Several considerations factor into sizing and shaping a tonneau cover gasket:
Truck Bed Size
Gasket dimensions must match the size of your truck bed for full coverage. Measure bed length and width to ensure a proper fit. Gaskets come in standard sizes for common truck models and bed lengths.
Different cover designs require specific gasket configurations. Folding and retractable covers need gaskets with specialized hinges or joints. The gasket shape adapts to how the cover opens and closes.
Covers made of metal, fiberglass, vinyl and other materials have unique requirements for gasket type and attachment. Gasket material and adhesive must be compatible with the cover. Some gaskets slide into built-in tracks while others adhere directly.
If a truck has a spray-in bed liner, the gasket must sit atop the liner. A liner-mounted gasket offers the best seal. Consider liner thickness when sizing the gasket.
Some gaskets seal just 3 sides, leaving a tailgate gap. But full 4-sided gaskets provide the most complete protection. Ensure the gasket you choose covers tailgate joint spaces.
Where Should The Gasket Be Installed?
Installing the gasket properly is key to maximize sealing effectiveness:
Perimeter Of Truck Bed
The gasket should run along the entire parameter of the bed where it meets the cover. All 4 sides must be sealed – front, back and both sides. This prevents any weak points that could allow leaks.
On Top Of Bed Rail
For optimal compression, the gasket fits along the top, outer edge of the bed rail. As the cover closes, it sandwiches the gasket against the rail to fill voids.
The gasket should seal the tailgate edge even when the tailgate is dropped. This ensures no dirt or moisture enters through the tailgate gap. Proper installation keeps the tailgate flush with the gasket.
Outward Edge Of Cover
The gasket should adhere to the outermost edge of the underside of the cover for maximum contact. When closed, the cover’s gasket-lined edge presses firmly against the top bed rail.
Avoid pinching or overlapping the gasket during installation. Any kinks or obstructions can impede sealing performance. The gasket works best when laid flat and smooth.
What Is The Best Gasket Material For Tonneau Covers?
The gasket material plays a major role in durability and sealing capability. The right material choice depends on cover type, truck usage and climate:
Closed Cell Foam
This gasket foam offers excellent compressibility for a tight seal along the length of the bed. The dense, closed cell structure also withstands weathering. Best for vinyl covers.
Rubber gaskets provide flexibility and longevity through extreme temperatures and repeated opening/closing. Works well for metal covers and rugged truck use. High-density rubber has increased tear-resistance.
Flocking gives gaskets a “velvet” texture that creates major friction against the cover and bed. This helps keep the gasket in place without adhesive. Great for folding covers.
Sweeping Brush Strips
For retractable covers, sweeping brush strips made of vinyl strands wipe dust and debris as the cover rolls open or closed. The brush fibers also seal gaps between slats.
Some gaskets apply as a silicone caulk bead. The permanent adhesive bead adheres covers tightly. Provides a decent seal but less convenience than removable gaskets.
How Can You Make An Old, Damaged Gasket Seal Again?
Over time, gaskets can warp, detach or accumulate debris that impedes proper sealing. But rejuvenating an old gasket is possible:
Use isopropyl alcohol to clean gasket surfaces and remove dirt buildup. Top brush attachments can help scrub vinyl or rubber gaskets. Avoid petroleum-based cleaners than can deteriorate rubber.
Warm and Compress
For rubber or foam gaskets, use a heat gun to warm the gasket. Then compress it with hand pressure to restore proper shape and thickness. Allow to fully cool before reinstalling. Be cautious not to overheat.
Seal Detached Areas
Reattach lifted corners or sections with weatherproof adhesive made for automotive sealing applications. Clamps can also temporarily hold separated areas together.
Inject silicone sealant into large gaps or tears in the gasket. Allow the silicone to cure fully before closing the cover. This fills voids to prevent moisture and dust entry.
Replace Compromised Sections
Cut out torn, overly compressed or otherwise deteriorated portions of the gasket. Replace these spots with new gasket sections adhered into place. Use materials that match the original gasket type.
Does Proper Gasket Maintenance Make A Difference?
Like any truck accessory, periodic gasket maintenance ensures lasting performance:
Check for gasket damage, gaps or diminished sealing after heavy use or extreme weather. Problems detected early are easier to remedy.
Clean out mud, gravel, snow or anything lodged under the gasket regularly. Built-up debris can impede sealing. Avoid using sharp tools to prevent gasket tearing.
Apply rubber protectant/conditioner to keep rubber gaskets flexible. Di Electric Grease also helps rubber slide smoothly when opening or closing the cover.
Overtightening clamps can squash the gasket unevenly. But loose clamps cause gaps. Inspect and hand-tighten any clamps regularly.
Misalignment can result in compression or pinching in some spots. Periodically check cover/rail alignment and adjust as needed for consistent contact.
In summary, the tonneau cover gasket serves the vital function of sealing gaps between the cover and truck bed rails. This barrier keeps out dust, moisture and other elements that could damage cargo or reduce MPGs. Choose a gasket material, size and shape right for your cover style and bed size. With proper installation and maintenance, a tonneau cover gasket barricades your truck bed contents against weather, theft and more.