Few manufacturers list a rating for downward weight on the tow ball (sometimes called tongue load).
It is recommended that this be no more than 10% of the towing load (trailer + load).
Impact on EV range
Towing a load will (sometimes significantly) reduce the EVs range. Pay attention to the aerodynamics of the load (lower speeds and a lower height of the towed load will help).
Often, tow bar installers will rate these at around 500 – 600 kg (unbraked). The downward weight on the tow bar should not exceed about 10%, which is good for carrying bike racks.
The issue is a structural one.
An EV’s instant torque and low centre of gravity mean it can tow well, but has the car been designed with an appropriate structural mounting point for a tow bar?
This is a grey area, and the EV owner should beware.
Braked vs. Unbraked
Although EV manufacturers don’t have much detail on towing, many specify electrically braked trailers (e.g. Polestar).
Electrically Braked
Electric brakes are controlled electronically and activated by the tow vehicle’s brake controller.
When the driver applies the brakes in the towing vehicle, an electric current is sent to the trailer’s brakes, which in turn applies the braking force.
Surge Braked
Surge brakes are a mechanical braking system that works independently of the tow vehicle.
When decelerating, the trailer’s forward motion (surge) toward the towing vehicle activates these brakes.
Unbraked
It does not have brakes, and the usual maximum gross weight for the trailer and load is around 750 kg.
