Well I'll kick this off and state that if looking for new wheels or tyres for your van then a few things need to be taken into consideration.
First off, the wheel stud pattern or PCD, on the T4 eurovan, this is 5x 112. So this is the first factor when looking for a suitable wheel.
Secondly the centre bore, this is the hole in the centre of the wheel that locates in spigot on the wheel hub, on the eurovan and 99.9% of all VWs this is 57.1mm.
So armed with the above figures you can start looking for your next set of wheels, which would include most wheels from Audi, VW and Mercedes, although Mercedes have the same pcd of 5x112 as VW, the centre bore is larger than VW , this can be overcome by buying spigot rings. ( search VW to Mercedes spigot rings on eBay ) .
Some other points to consider:
Early eurovan as standard may have came with 14 inch wheels, fitting these to newer vans may not be possible as they may not clear the brake calipers.
Wheel ET , is also a consideration , this is how far the the wheel sits of centre ( or away from the hub ) a too high of an ET may cause problems as it may foul on suspension components, or scrub on the fenders or not allow full lock on steering, the ET of a wheel is also effected by the with of the rim, a 5j rim is narrower than a 6j rim etc .
Also remember that your Eurovan is based on a commercial vehicle and is heavy, so when considering what wheels to choose, the load rating needs to be considered, usually the manufacturer will be able to advise on this and is usually stated on their website and is stamped on the inside of the wheel, where as fitting VW or Audi wheels etc don't usually have these markings but you may be able to Google the part number stamped on the wheel to obtain this, but generally car wheels will not be rated for van use even tho they physically fit, which is common sense as a VW Golf weighs far less than a Eurovan.
Tyres:
As above tyres need to be load rated too, you can fit car tyres or commercial tyres, car tyres generally have a lower profile than a commercial tyre and will wearout quicker. Load rating for the tyre is on the tyre after the size, eg. 205/65/16c 101.
205 is the width of the tread area. 65 is the side wall aspect ratio , that is in this case 65% of the tread area. 16 is the rim size in inches. " C" designates a commercial tyre. 101 in this example is the load rating, in a car tyre of the same approx size the load rating may be around 91 or if its extra load tyre 94 which is too low.
That's enough for now, I'll edit this post of typos and will add further info as it comes to me.
Further reading here:
http://www.carbibles.com/tyre_bible.html