Spacers?

[e30itis]

my dumb self bought  15 inch basket weaves from an ix thinking it was a straight swap for the 14 inch bottle caps i have on my 318ic looks like the have different offsets can i use then with spacers and what size also longer lugnuts?.pse help:(

[DesktopDave]

From what I've googled the iX has 15x7 ET41 rims.  Your stock bottlecaps are likely 14x6 ET35.  

152mm rim - 35mm offset = 117mm from hub face to inner rim..
178mm rim - 41mm offset = 137mm from hub hub to inner rim.

So if I've done my math OK you'd need 20mm alu spacers to clear the struts.  If you're willing to risk spacers, I'd go with a stud conversion to match.  Racing studs are likely too long for the street (usually 80-90mm from what I've seen), I'd suspect you'd need about 60mm.

It's going to be expensive no matter how you do it.  I'd suggest you sell them to an iX'er and get custom rims or the Euro BBS 15" rims we all really want.

Here's a great link for e30 rims...http://www.maxbimmer.com/forums/showthread.php?t=54146

[e30itis]

risk?pardon my ignorance but is there a risk with spacers?aaaah these novice mistakes r costing me

[DesktopDave]

No prob...that's why you're here, to ask the experts...until one shows up I'll tell you what I know...

Spacers move the rim further out, putting far more load on the studs or lug bolts.  Some spacers are plastic as well, they can deform from brake heat and cause the rims to become unbalanced.  20mm aluminum spacers are as far as I'd go.  If they were steel I'd be tempted to go further.

I wouldn't even trust plastic for hub-centric rings - they allow you to properly center 4x100 pattern wheels with larger hub bores than our 57mm.

There are also adapters that bolt to the hub (4x100 pattern) and have another set of studs installed (say 4x114mm or 5x125).  That allows you to use rims made for many different cars but I'd personally avoid them all.  I've had rims come off cars (happily at low speeds) and it is never pretty.  Getting a broken lug bolt out is an incredible PITA.