Steve I guess I don't understand your comments on weight. I just googled a 2009 Ford Escape with 16 inch wheels and it's 4700 pounds then add a full tank of gas to bring that up to 5000 lbs then add four adults at 200 lbs that teeters on 6000 lbs...a 3400-4000 lb trailer on 15 inch wheels seems reasonable....
Please help me understand the weight issue.
The example you mentioned only has 6000 lbs on 4 wheels, or roughly 1500lbs per wheel. A 4000lb Bigfoot will load it's 2 wheels at closer to 1850lbs each wheel when weight transfer from the WD hitch is factored in. If you start to search for aluminum automotive wheels with a compatible bolt pattern, you will find few or none with this load rating. You can of course, find some automotive rims and many truck rims that can handle this load, but they will have very different bolt patterns and offsets than the common trailer standards.
The other problem is that trailer tires with a high enough load rating will require up to 60lbs pressure, again most automotive rims are not designed or rated for this high a pressure.
This is of little concern to most other smaller fiberglass trailer owners, whose loaded trailers are less than 3000lbs. They are free to safely use pretty much any suitable sized rim that will bolt up.
The last time I actually weighed my Bigfoot at the end of a trip, it showed 3600lbs on the axle with an near empty water tank. Fully filled and loaded up, I am sure it would scale at 3900-4000lbs at the axle, which would imply a total weight of 4200 - 4300lbs as the tow vehicle is supporting some of the tongue weight. This also means each wheel would be supporting close to 2000lbs, assuming the load is centered (unlikely), and was the reason I upgraded my axle/suspension, wheels and tires.
I'm sure my unit is on the heavy side for a 17 Bigfoot, as it is well optioned out including an air conditioner, which adds another 120lbs or so. Even so, I doubt it is much more than 300lbs heavier than an average loaded 17 Bigfoot weight. I think the 80's 17 footers are somewhat lighter than average as their refrigerators were smaller and many came without an oven, awning
or the extra fiberglass cowling over the propane
tanks and spare tire. Options like Fantastic fans, day/night shades and skylights didn't even exist for the early models either, all which add to the total for newer models.
Bigfoot themselves even seemed to acknowledge the increasing gross weights in 2004, when they switched from 14 to 15 inch rims before abandoning the 17 for the new 2005 17.5 with a 4400lb GVW