How much can we tow with SUV?
Looking for a travel trailer to pull with an SUV. Tow vehicle is a 2019 Yukon Denali 4x4 with a tow rating of 8100 lbs. and a payload of 7300. It seems like the latter will be the limiting factor. May...
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Sorry for a long answer to mkirsch. First, the OP was asking about towing a trailer with an SUV, and SUVs tend to have a short wheelbase suitable only for smaller trailers. SUVs also tend to have a high center of gravity due to high ground clearance and a narrow wheelbase - this makes them inherently less stable, and thus less suitable for towing. Secondly, the source of the wheelbase “formula” for the rule of thumb of 110" for a 20' trailer adding and subtracting one foot of trailer for each 4 inches above or below 110". Source: "How to tow Safely - A Complete Towing Guide" by J.D. Gallant, 2003 published by RV Consumer Group. (My comment: lots of technology advances since 2003!)
If we were talking about trucks, then I would not have mentioned the “formula” since a commercial truck with a short wheelbase tractor can pull a 53 ft. box trailer at highway speeds without issues because it's hitch is directly over the rear axle so there's no lever arm to affect the direction of travel.
Towing a travel trailer is a combination of lengths and weights and countermeasures. Wheelbases are like pivot points and the distances between them are like levers. If you push sideways on the rear corner of the TT, the wheels act like a fulcrum and the torque moment is coupled to the hitch ball, the next pivot point. The force X distance product for each end will be the same so the shorter the distance from the rear corner to the wheels, the less force is applied to the hitch through the longer moment arm. At the hitch, the next fulcrum point would be the rear axle of the tow vehicle, again the distance between the hitch and the rear axle becomes the moment that gets transferred to the front wheels. This is where the wheelbase comes in to play, the longer the wheelbase, the less force is applied to the front wheels. As far as weights go, if the tow vehicle weights more that the trailer the tail can't wag the dog, however if the trailer weighs more than the tow vehicle, the tail can wag the dog.
Proof of this leverage is the 5th wheel hitch, which puts the hitch directly over the rear axle and eliminates the lever arm between the hitch and rear axle that allows side forces to affect the direction of travel. This makes 5th wheel trailers inherently more stable than bumper pulled trailers and the lack of a lever arm largely removes the wheelbase of the tow vehicle from handling considerations.
If we were talking about trucks, then I would not have mentioned the “formula” since a commercial truck with a short wheelbase tractor can pull a 53 ft. box trailer at highway speeds without issues because it's hitch is directly over the rear axle so there's no lever arm to affect the direction of travel.
Towing a travel trailer is a combination of lengths and weights and countermeasures. Wheelbases are like pivot points and the distances between them are like levers. If you push sideways on the rear corner of the TT, the wheels act like a fulcrum and the torque moment is coupled to the hitch ball, the next pivot point. The force X distance product for each end will be the same so the shorter the distance from the rear corner to the wheels, the less force is applied to the hitch through the longer moment arm. At the hitch, the next fulcrum point would be the rear axle of the tow vehicle, again the distance between the hitch and the rear axle becomes the moment that gets transferred to the front wheels. This is where the wheelbase comes in to play, the longer the wheelbase, the less force is applied to the front wheels. As far as weights go, if the tow vehicle weights more that the trailer the tail can't wag the dog, however if the trailer weighs more than the tow vehicle, the tail can wag the dog.
Proof of this leverage is the 5th wheel hitch, which puts the hitch directly over the rear axle and eliminates the lever arm between the hitch and rear axle that allows side forces to affect the direction of travel. This makes 5th wheel trailers inherently more stable than bumper pulled trailers and the lack of a lever arm largely removes the wheelbase of the tow vehicle from handling considerations.
