before you jump on me ;-), I did search and found very little that was helpful, and ...I have thought this through...

...lug pattern is the same, but center bore is different (78 on truck, 108 on van). my motivation is that I also have a truck and have several sets of wheels and tires on hand already... I'm going bigger and so will need to run spacers or different wheels to get some clearance anyhow. I'm thinking ...

...spacers with a 108 center bore to match the van hubs and make a small adapter ring out of 7075 to slip into the 108 center bore that'll provide a 78 mm hub on the outside to mount the truck wheels OR more likely to buy spacers that have 78mm center bores, and turn the inside part of the bore to 108... either way, the overall result will be the same - being able to run truck rims and having enough clearance with the truck rims. as long long as the spacers are well made and fit correctly, this won't put any more stress on anything than buying rims with appropriate offset...

any experience?

 

Be sure to purchase spacers rated for RWD trucks. Some of the billet spacers are rated for this, some of the cast spacers are not.
Steve

 

understood regarding quality billet spacers - that's the plan... although looking like I'll only need spacers on the rear... I dragged a solid front axle assembly home this evening (out of a truck)... so I'll only need spacers on the back to be able to use the same rims on all four corners...

 

This worked great. Use 2" billet aluminum or steel hub-centric spacers for dodge ram truck (5 x 5.5 with 78mm center-bore) so the wheels will be centered and held securely on the outside of the spacer. The hub diameter on your van will be 3.5 inches (ca 98 mm) so you'll need to have one of your friends with a lathe turn out the center-bore on the hub side of the spacer to 3.5" to a little more than a half inch depth (about 0.6 inches). Note that anything less than 2" spacers and the hub will contact the inside of the spacers near the wheel side and keep them from seating. your tires would also still be too far in with the positive offset of the stock truck wheels (the van wheels have negative offset - they stick out quite a bit further from the mounting surface than the stock ram truck wheels do)

...at the same time I added 2" spring spacers in the front and a set of stock ram truck 4x4 (3") lift blocks and u-bolts in the rear. Now 265 75 r16 tires on stock 16" 2nd generation 5-bolt dodge ram rims fit about perfect. they don't stick out much more than stock and other then the additional bolt / contact surface required by the spacers won't put any more wear and tear on the suspension than new wheels with appropriate offset.

I was particularly interested in being able to run second gen truck rims and tires because I have a 95 1500 4x4 and so already have several sets of rims and tires on hand... The original 16" steel wheels off 2nd gen ram trucks look just about exactly like the original van wheels if you want to run stock looking wheels...

I'll post a few pics when I get a chance later in the week and let you know if the 285 75 r16s off my truck rub anywhere when I put them on the van... Cheers!