The stock e46 wheels have an offset of something like 46mm. The e92 has 28mm offset. Your aftermarket (I assume) wheels for the e46 might be as low as et35. You need no less than 10mm spacers. You should use the ones from H&R or even better the ones from Rogue Engineering. Most spacers less than 10mm are not hub centric and should not be used. Make sure your spacers are hub centric.
Be aware. There are a few things you need to know in order to get this right. Your goal is end up with an offset in the front between 25 and 30mm. This means you have to know the offset of your replacement wheels. You have to make sure your spacers are compatible with both your hubs and your wheels. You also have to replace the wheel bolts with the appropriate length for your wheel and spacer combination. If you are not comfortable figuring this out, then go to a knowledgeable tire and wheel store to get it done properly. The last thing you want is broken parts in your front suspension.
Dinan compliment of stuff plus PF rotors and RG63s. Enough for now.
Why, yes. I am an abrasive bastard.