I modified my stock rear 4-bolt hubs by drilling and taping them to the 5-bolt pattern. To get more threads in the new holes I milled the back of the flange flat and welded on nuts to the back side of the hubs. I can now switch from the cheep VW wheels or the more expensive alloys when ever I want.

The question I have is do you need to balance the hubs or would this be over kill?

Normally, we press in the Porsche studs and tack weld 'em instead of using the lug bolts. I don't think that you need to balance 'em unless you really loaded up the welds.
Geoff

I ran across a set that was balanced that prompted me to check other ones I had that where not balanced. The ones I checked (drilled 5lug with STUDS) where so close to being balanced that I didnt feel/see a need to balance them.

I think your playing with fire running nuts on the back side. Part of the reason we run the studs is for strength. The studs are Rockwell hardened.

Let us know how it works out.

B

I have mixed feelings on this.....if done properly, I see no real issue with the tapping of the hubs if the material thickness is not comprimised and one has at least 75% thread engagment (normal Class B fitment)
I'd use a tap drill smaller than recommended to get a tighter fit myself.

The addition of the nuts on the farside of the hub is a good idea and would be better if using high strength nuts and not "regular" nuts as found at Orchard Aircraft Supply

Now the real question is, do the bolts fit the new wheel choices correctly? I have a rim for a Honda (aftermarket Kosei Racing rim) that I thought I could drill and tap the hubs for and use the factory bolts...but I cannot, the mounting surface between the bolt and the wheels are different....ball socket verses angle socket...

So, I either use studs and the correct lug nuts or find lub bolts with the correct mating surface (which I doubt are available, but I might be wrong)