Single Axle vs. Double Axle

You’ll often hear, or read on a forum, that someone knows someone who says they wouldn’t drive anything without a double axle. They go on and on about better tracking or better safety, etc. Usually, these comments are made by individuals with little or no understanding of engineering or design. Let’s break this myth. The Bowlus is safer and better designed with a single axle. And, you guessed it – weight determines needs.

Every tire has a load capacity, and this dictates the requirement for the number of tires; a car, because it’s heavy, needs four tires, and a motorcycle, only two. Recreational trailer tires hold a load capacity specific to each tire. In the case of a Bowlus, with a gross vehicle weight rating (GVWR) of 4,000 pounds for the Endless Highways Edition, we use Goodyear Endurance 205R15 at 65psi with a load; this equates to 2150 lbs. per tire. This dictates just one axle and two tires. The 25’ Airstream, on the other hand, has a GVWR of 7600 lbs. For such a heavy travel trailer, two axles and four tires are required. Let’s ignore for a moment the arguments that two axles greatly compromise interior layouts and reduce interior space or that they cost twice as much to replace or maintain. Instead, let’s look at how aerodynamics, specifically weight balancing, and the design of an RV impact tracking and safety. Our owners tell us that when they’ve experienced challenging driving conditions (particularly down mountain passes) with other, heavier travel trailers they’ve owned or rented, a double axle did not deliver better tracking or provide a feeling of more safety. One Bowlus owner shared with us that, due to the poor handling of a heavy travel trailer he was once driving, he was pulled over for a suspected DUI. Additionally, tandem axles have twice the running gear weight which results in slower acceleration, more braking, and the need for a heavier tow vehicle. All of these measures still don’t cancel out poor handling. With the Bowlus, and its incredible weight distribution and a lower center of gravity, sway is never an issue. The Bowlus’ low weight also makes it easier to rotate on two wheels (with the jockey wheel), so it can be positioned anywhere.

Lastly, let’s touch on tire maintenance. You should regularly inspect your tires for damage and keep your tires properly inflated. This can be easily completed during your circle check before you leave your campsite. RV tires, depending on how they are stored, can deteriorate due to poor maintenance and exposure to UV light. (We partially address this with our fender skirts that you can personalize with the name of your Bowlus). The #1 cause of RV tire blowouts are old tires and overloading. The idea that you can simply “limp” home on 3 tires doesn’t compute since the heavier RV still requires four tires, and severe damage will result from traveling with even one damaged tire. So, remember to replace your tires every seven years, even if they look perfect; it’s a small price for safety. Finally, consider upping your AAA membership to include your RV. It’s good to know you’re not alone. Let us know if you have any other questions you’d like us to address.