Max tow capacity is a theroetical number. Lets say that your 7000 lbs figure is correct. In theory, Toyota says a 2 wheel drive Tundra with 150 lb driver and a full tank of gas, can tow a flat bed trailer weighing 7000 lbs and it has 1300 lbs of payload.
Anything added by Toyota, the dealer, or the customer, takes away from payload and towing capacity.
Example:
Toyota adds 4X4 (200 lbs), now the tow capacity is 6800 and payload is 1100 lbs
Dealer adds a bed mat, floor mats, nerf bars, and sattelite radio (175 lbs), now tow capacity is 6675 and payload is 975
Customer adds WD hitch (100 lbs) and passengers (400 lbs) , now tow capacity is 6175 and payload is 475 lbs
Tongue weight on a 6000 lb trailer will be about 720 lbs.
The 6000 lb trailer is still within max tow capacity, but, the payload is overloaded by 245 lbs, and any type of cargo will overload further.
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