It is a 7,000 lb. Airstream. The big problem he is running into is that the tongue weight is 800 lbs. Plus he want all the knick knacks that make driving with kids easier. Really limits your choices when you want to go Japanese, and particularly Toyota.
And another question, he asked me the difference between the Land Cruiser and the Lexus LX. I know that suspension/drive-train wise, the only difference between the FZJ80 and the LX450 was softer springs -- is that still the case? He is contemplating the LX and swapping springs.
The Lexus 200LX towing capacity is even lower, 7000 lbs. I think it is due to the AHC. Remember the rule for towing, you should be towing something 25-30% less than the Max tow capacity of your vehicle. So if you're towing a 7000lb Airstream you probably want a vehicle with something more like a 9500lb tow capacity. I'm sure Airstream would be the best ones to contact. Or Colonial Airstream in NJ, they would be able to recommend minimum tow vehicles for their trailers.
Toyota recently re-rated their tow ratings and lowered them. So I'm not sure if the 25-30% rule would still apply with the new rating??
Anyway, the guys at Colonial could shed light on your brothers problem.
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Here are the Toyota tow options in 4x4:
2011 Tundra Double Cab 5.7 v8 4x4__9800lbs
2011 Tundra CrewMax 5.7 v8 4x4____9000lbs
2011 200 Land Cruiser 5.7 v8_______8200lbs
2011 Sequoia 5.7 v8 4x4___________7100lbs
2011 200 Lexus LX 5.7 v8__________7000lbs
All of the vehicles above have a Payload of approx 1400-1600lbs. So a tongue weight of 800lbs leaves 600-800lbs of payload (people, gear, etc).
Also, if he wanted just to tow, the 2wd versions of some of those vehicles are rated a little bit higher. Although 2wd on a truck just seems wrong to me.