As odd as it seems it is true. Full size vans are trucks with a long roof. Mini vans are a combination car/truck uni-body with a long roof. A Chrysler mini van can haul approximately 1400 lbs total. That includes passengers and everything you have added inside the van that was not there when it was on the show room floor including a water bottle. Same for the Tundra. So if your brother-in-law put 1400 pounds of soil in the van and then he got in to drive it, he was over loaded.
The difference is the Tundra is a truck with a frame and it was made to tow and work in rugged enviroments. Your Tundra has approximately a 10,000 pound tow rating and a 1000 pound tongue weight. That 1000 pound tongue weight counts ageist the bed load capacity and same for the mini van.
The mini van has a 3600 pound tow rating and a 360 pound tongue weight. That means 360 pounds is counted ageist the van load rating of 1400 pounds. So now if he is towing 3600 pounds he can only have 1040 pounds inside the van. Four people without gear in the van and you are over loaded. Most recommend not being within 10% of load capacity.
1/2 ton trucks are that compromise of a work vehicle and daily use. Some 1/2 ton trucks haul more than others. Some say a 3/4 ton truck is a compromise between 1/2 ton and one ton. It all depends on what your needs are. My Tundra has hauled and or towed everything I have ever needed. I have added a few thing that make it a more compliant tow vehicle, E rated tires, air bag over load springs. These things do not change the tow or load capacity but they do make it handle a full capacity load better. I have had 2000 lbs in the bed and four people in the cab. Yes it was only from Home Depot to my house but that is a 100 miles. Yep, over loaded and drove almost as if nothing was in the back. People tow 14,000 pound fifth wheels with Tundras. Is over loading smart, no but it happens. Trucks really excel in rugged off road environments even when loaded and other vehicles don't.
Ask you brother-in-law how much time the Chrysler mini van has spent in the shop. Even the car magazines reviewing the Chrysler mini vans can not keep them out of the shop. Your Toyota won't have those kind of issues.
