i had the same problem with the old bongo, had new front tyres and had them balanced, 3 months down line, same again wear on both edges, took it and had it 4 wheel alignment done, and he couldnt do it to start with because there was too much play in the bushes, hence the side wear on the front tyres
(the machanic told me thats why my tyres are balding on inner and outer edges, but he said it to me as thoe i should have known that
) i had to have the lower and upper wish bone bushes replaced at about £80 for all 4.
had the bongo for about 3 days after having them replaced and then it got wrote off on way to silverdale so cant really comment if it would have made any difference over time but the handling was totally different, well improved much firmer ride and was really stable going round corners compared to what it used to be like.
Worth having them checked, for what it cost for the bushes, cheaper than having to buy 2 new front tyres.
Sorry, I'm a believer in the pureness of the original design, including wheel trims, although I think they may be a bit better on the later models? Unless you subscribe to that philosophy, you can't be truly mean - so I claim the crown as King Scrooge 
so i dont have to go into detail 
