Your best return for the dollar is in 15 inch tires. The 48psi that the 85
westy requires,makes the tires hard rubber sound transmitters. Sound
deadening  MAY just cover ths up a bit.Maybe not. 15 inch tires that
inflate to say, 35psi, will reduce the road noise.After that, all the other
sound deadening products will work almost equally. Be creative , and save
money.At a junkyard,study what manufactures use, and where they put it.The
foil backed aftermarket product will make the doors shut like a Cadillac. I
used a underhood soundliner from a late Buick(very clean $5), for the rear
hatch.Fits very nice.This will do the sliding door,too.Not the front
doors,as the window is in the way.Need a spray on produce, there.A major
concern is vapor release from the produces you use.Personally,I would not
use anything for undercoating,and out of a spray can, on the interior.
Sound deadener on the fan schroud.Kool Seal was a failure. Went on in the
wheel wells fine,but is flaking off,badly,after 2 years. The lower priced
roofing product is still perfect ,on the front wells.I used large sheets of
sound deadening material from a 90 Dodge caravan(dont use a later year).I
used it below the floor boards in the westy.It gave great results for $5
(entire floor). Has the tar like backing that the expensive stuff has.I
think most folks here that report good sound reduction have late vanagons
to begin with.They have the 205 sized tires,and improved factory sound
deadening.If you think the more money you spend will do the mostest,you are
wrong.Start with the 15 inch wheels .