I've looked at the regs for brakes on trailers, but I'm not sure how it would apply to flat towing a vehicle. My '92 Jeep weighs in around 3,000 lbs (spec curb weight is 2,855–3,241 lb (1,295–1,470 kg)). We'd be pulling it with a 2015 Yukon 4WD (rated towing weight 8200 lb/ 3719 kg, curb weight 5707 lb / 2588 kg).
The regs say: