I Carry a lot of loads too and recently replaced rear springs (king Springs) and heavy duty shockers from Pedders. I'm happy with the solution. Rear looks now like there is no load at the back at all, handing is not affected. More in this post. http://www.vwwatercooled.org.au/f136...tml#post439571
The van has 17" steel wheels with 235/55/17 tyres.