The Tundra 4x4 has a max towing capacity of 10,100 pounds depending on configuration. We had the opportunity to tow four trailers with a 5.7L-powered Tundra. This trailer with tractor had a total weight of 8,500 pounds. We towed each trailer with and without using the Tow/Haul Mode, which is specific to the 5.7L-powered Tundra. Without using the Tow/Haul Mode the engine and transmission did well, but activating Tow/Haul brought the pair to life with more power and improved engine braking performance. Each truck was equipped with the Towing Package that includes a slew of features including engine and transmission oil coolers and heavy-duty battery and alternator. The optional tow mirrors are worth the money and Toyota says that an electronic trailer brake controller accessory will be available soon.