Proper Loading of Triple Axle Trailer to Minimize Sway

Updated 03/21/2019 | Published 03/20/2019

Question:

Im thinking of buying a trailer that has had a third axle without brakes installed in front of the original two. the trailer now stands level without using the jack stand, no weight on the tongue with no load. Will this affect how this trailer handles on the road as far as swaying goes at highway speeds? Any thing else I should be concerned about? Three 7000 lb. axles, 18 Ft. OA flatbed, pintle hitch. Thanks.

asked by: Wayne M

Helpful Expert Reply:

The fact that your modified trailer has a third un-braked axle added in front of the two braked axles will not directly affect sway. Nor will the fact that it seems to balance pretty well on its own without a load.

Trailer sway, or the lack of it, is mostly a function of load distribution. If the loaded trailer is too light at the tongue (too heavy at the rear) the rear of the trailer will tend to swing like the pendulum on a grandfather clock. Tongue weight (TW) should always stay in the range of 10 to 15% of gross weight to keep sway under control. We offer a tongue weight scale # e99044 which can read up to 2K. This is a handy way to know for sure how well your load is distributed.

Other methods to measure TW are outlined in the linked article.

Multi-axle trailers, especially triple axle trailers, tend to pivot on the front axle, because this axle is closest to the tow vehicle, and this can cause what is called "scrubbing" of the rear axle's tires as they kind of get dragged along for the ride as the trailer pivots on the front and center axles. For this reason tires on the rear axle of a triple axle trailer can sometimes wear out faster.

Also please note that if the trailer was manufactured with two axles its rated weight capacity will be based on those two OEM axles, as determined by the manufacturer. There is no guarantee that the addition of the third axle has increased the trailer's actual weight carrying capacity. It is entirely possible that the trailer's frame could be its weakest part.

If this were the case the additional axle would certainly reduce the load on the two OEM axles but this cannot be assumed to have increased the trailer's load capacity above what the manufacturer indicates on the VIN/capacity sticker.

expert reply by: Adam R