42" or 54" bolt-on Roof Rack rails?

I've decided that I'm going to bite the bullet and drill some holes in my roof for a bolt-on rack, but I'm undecided what length of track to buy.

My thinking thus far is that I prefer a track over the simple landing pads for weight distribution and flexibility in bar location. Following that train of thought then, a 54" track seems to accomplish both objectives better than the 42" track (Yakima tracks).

I've measured my roof line and it appears like the 54" track should fit just fine. I've also seen a few 54" installs floating around the internet, but it seems like the vast majority go with the 42" tracks.

Does anyone have experience installing either length that they'd be willing to share? Is there a good reason that most of these installs seem to use the 42" track? And additionally, are there any locations in the roof that I need to avoid when drilling (ie. underlying structural beams, wires, etc.)?

Any help would be much appreciated. I clearly want to get this right the first time.

 

Thank you for the input. I already have a hitch, a bike rack, and a small trailer so I am already over the debate about which hauling system is best for me. 5 years ago, I chose a hitch system and I've loved the utility that it added to the car...no regrets at all, and I'd 2nd your recommendation to others. This roof rack will be installed for the purpose of giving me even more options and additional flexibility/convenience for my cargo needs. This is not an either/or proposition, it is an AND proposition.

Incidentally, and for sake of framing in this thread discussion, I'm also not debating clip-on rack vs. bolt-on rack. I've decided on a bolt-on roof system, and now the only question remaining is what size track. I'm just wondering if there are any logical arguments for (or against) either the 42" or the 54" size.

 

Sorry for not adding any closure to this thread. I decided to purchase the 54" tracks with the intention of cutting them down a few inches if necessary. When the tracks arrived, I placed them on my roof and began to gently arch them over the roofline. I very quickly became uncomfortable with the amount of stress that the arched track was going to place on the front bolt, and I wasn't even close to touching the roof with the track because I wanted to make sure that I didn't bend the track...which I was now beginning to realize was going to get returned. The problem is that the Prius roof curves so quickly that almost all of the track tension is concentrated between the first and second bolts. the rest of the track will bolt down relatively flat, but that front section will get pulled down exclusively by the front bolt. I also knew that I was going to run a cargo box which has the potential to create lift (and "bouncing" forces) on the front tower, which incidentally also lands between the first and second bolt holes. All-in-all, I just wasn't liking the odds of that front bolt having a long life. Additionally, I realized that a pair of parallel tracks was not going to look right (IMO) next to the pair of unparallel rubber roof seams. Running the tracks parallel to the roof seams would look better, but would negate one of the largest benefits to a tracked system; the ability to slide the towers (still firmly attached to the bars) fore and aft. I also discovered that the tracks would be twisted along the path as well since the Prius roof is curved in both directions. The nail in the coffin for my track plans though was the plastic end caps that are supposed to finish off the rails. Along with the rest of the track, they are designed to be mounted on a flat surface and their only attachment point is the one screw holding the front edge of the track, and that screw is way behind the body of the end cap itself. On the Prius, that plastic cap was going to "float" more than 1/8" off the surface of the roof due to the curved roofline. For me, that alone just wasn't going to work (undiagnosed OCD, lol). They market these tracks as being identical to a factory installed rack, but that just simply isn't true. The bottom of the track was a piece of plastic extrusion. I was expecting double sided foam or a rubber seal...or something...anything. Factory roof tracks are sealed from water along the entire length of the track. These tracks are only sealed at the actual holes in the roof. Water will travel underneath these tracks and it will sit there since there's no clear path for it to escape. Overall, I was very disappointed with the implementation of a roof track system by both Thule and Yakima. Rather than trying to remedy all of the various problems with this situation, I ultimately returned the tracks and went with control towers and landing pads.

From day one, I preferred the look of the landing pad "warts" when the rack is off but I was always concerned about the concentrated weight loads. I exchanged several e-mails with the infamous EVNut and he convinced me that his roof/landing pads have held up well to several years of abuse. He also gave me the tip of popping off the dome light to be able to see under the headliner. That tip was huge for my confidence level. You can see both of the rear roof beams clearly from the dome light opening, so at that point I knew that I'd be able to avoid them. I independently arrived within 1/8" of Darell's front pad position, so I adjusted mine to match his since I knew that he didn't hit anything when he drilled. Then I set my rear towers back a little bit farther than his for more bar spread (35.5" center-of-bar to center-of-bar...NOT measured at the tower bases). I was shooting for 36" spread, but I got nervous about hitting the rear roof beam so I backed down 0.5". Be warned that 36" would land a hole VERY close to the beam. I actually think that it would work in retrospect, but I wasn't willing to take the risk. Having installed the landing pads and using them on a 10-day family vacation with ~250lbs up top I am 100% satisfied and have no regrets opting out of the tracks. If I were to REALLY want the tracks, the only way that I'd feel good about mounting them would be to have them pre-bent to match the roofline of the Prius so that the front mounting bolts weren't under constant stress. The other thing I'd mention for the sake of additional information is that the bolts for the landing pads are much larger than the bolts for the tracks. Although, you'll presumably have more bolts in the track, the landing pads have two much larger bolts in close proximity to each tower.

I hope that ALL of that doesn't discourage anyone too much, but I thought that it was worth sharing my experience. I was frustrated with the lack of information about this subject myself when I was going through this ordeal. If anyone proceeds with a track installation, it would be beneficial for everyone to hear about your experience. Good luck!

It seems off-subject now, but I've attached a picture of my final install loaded up.

 

Sorry for the delay, I haven't been out on this forum in quite a while. I bolted the Yakima #7 Landing Pads (#8000227) to my roof. I used the Yakima "Control Towers" (#8000214) with their standard SM (48") round bars (#CROSS-BARS). IIRC, I might've even cut those cross bars down a little. I actually no longer have my Prius, but I used that roof rack system a TON over the course of 6 or 7 years. The ability to take the entire rack on and off in a matter of seconds is game changing...literally less than 30 seconds.

I know you didn't ask, but I'm sure that somebody will want to know... Leaving the empty rack on dropped my mpg to 42-43. I didn't observe any change in noise or mpg with the rack off and only the 4 "warts" remaining. With the cargo box only, I'd pull around 40 mpg and with the cargo box and two bikes (plus two bikes on a hitch rack) I'd drop to 35-37mpg. Two bikes up top only was slightly better than two bikes plus cargo box, and 4 bikes up top was a "worst case scenario" between 33-35mpg. All of those figures are rough averages. Headwind and tailwind conditions change things up or down significantly.