I began installing a new TonnoPro Tri-Fold today for my 2010 model. Upon setting the cover on top of the bed to square it up for installation, to my dismay, I observed a 5/8” open gap between the top of the front bed rail and the bottom edge of the tonneau cover. This would never do… I bought a tonneau cover specifically to keep stuff dry in the bed!!!
As most of you may know, there is a differential in the height of the side and front bed rails on a Tacoma, the front being somewhat lower than the adjoining side rails (see photo). Duh! You’d think that the folks that manufacture these covers would notice and adjust their design accordingly to keep the water out. As much as they charge for them, we deserve better!
I don’t believe this issue is specific to TonnoPro, since I’ve observed similar complaints from others in the TW forums using different brands of tonneau covers.
Consequently, I began searching for some type of weather seal or methodology to seal the gap between the bottom edge of the tonneau cover and the top edge of the front bed rail. I couldn’t find anything adequate at any of the local auto parts stores, so I took a look at what Lowe’s had to offer. It was pretty slim pickings there until I happened upon their water pipe insulation. They had two types: One was made of polyethylene and the other of rubber. Both were pre-slit and self-sealing. I opted for the ½” pipe rubber version, since it is more compliant for sealing and is more durable (see photos). It comes in a 6’ length and sells for $4.98.
I proceeded to remove the front cargo utility track that holds cargo tie-down cleats (see photo). I then attached one edge of the self-sealing pipe insulation to the back of the utility track, with the intent being to clamp the edge of the insulation between the utility track and the front of the bed that it bolts to (see photos). The self-sticking inside edge of the insulation made it easy to attach one edge only to the back of the utility track.
Note: It is not necessary to remove the protective plastic tape covering the self-sealing edge on the opposite side of the insulation, just leave it on.
Note: For those of you who may have more forward fitting tonneaus, you may want to stick the pipe insulation to the rear surface of the front bed rail instead of the back of the utility rack. This moves the pipe insulation about an inch more forward. Check the position of the front seal on your tonneau to see if it lines-up better relative to the top of the utility rack or the top of the front bed rail.
I then bolted the utility track back onto the front of the bed leaving some extra insulation protruding from each end for final trimming (see photo).
Using a razor blade, I trimmed the ends of the insulation on an angle to match the slanted taper of the side rails (see photo).
As you can see, after clamping down the tonneau cover there is no longer any trace of a gap to allow the ingress of water.
After finishing, I took my Tacoma to a car wash and subjected the front edge to prolonged spraying with a hand held nozzle. Not one drop of water entered the bed!
I hope that this tip will be beneficial to others.