[DanEC]

I slathered plenty of anti-sieze lube on pins and hubs of both the wheels and the adaptor. Once they had been on a time or two I wiped the excess off. I also used the 5-pin wheels and adaptors (I know we are looked down on amongst the 6-pin crowd) and had a problem on my rear wheels because the ERA lug bolts were too long and had to be trimmed off per the instructions from Vintage Wheels. The fronts were OK.

I wanted to maintain as much length as possible and trimmed them with an air driven cut off wheel after marking them with a template. But I managed to get a couple that were just a few hundreds too long and when I tightened the adaptor and pins in position their over length (and end surfaces not being 100% flat) cocked the pins just enough that the wheels would not slide on.

After realizing this I went back over the lug bolts with my micrometer and figured out the couple that needed a touch of grinding to shorten them and re-installed and then the wheels went on OK just with thumping on the sidewalls with my palms. I learned that it doesn't take much to distort the adaptor and pin very slightly to create interference.

I think Vintage just brought out FIA wheels - is that what you are using or Trigos? Did you trim the rear lug bolts?