BMW: Wheels for E30s, bolt pattern, honda wheels

Question
This is where I get confused.  I have an 88M3 and understand they are different, but I also have two 88iXs and they are 15x7 with 4 bolt pattern. My other 88s 325, 325i, 325is & 325ic all have 14x6 wheels with a 4 bolt pattern.  If I decide to upgrade to a 15" wheel on these e30s, I obviously need to make sure the wheels are 4 bolt, but what tire sizes should I consider and I do not know where to find the offset, as I do not want to use spacers, thanks again.  Steve
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Followup To

Question -
I have seen other BMW owner's switch the BBS style wheels on their E30 from 14" to 15".  How come this does not cause a problem and when can you go from 14" to 15" and from 15" to 14" with your wheels?  I do understand they need to have the same bolt pattern, but what I am unclear on is how do you know they will work properly, as the manufacture's owner's manual recommend a certain diameter.  Example most E30s 1988 - 1991 come with 14x6 with a 4 bolt pattern and the M3 & iX have 15"x7" with a 5 bolt pattern. So, if I have the proper bolt pattern can I put a 15x7 wheel on an E30 that came with a 14x6 wheel? I also do not want to use spacers.  Thanks

Answer -
Steve,
 Good question...

 First off, Some E30's were offered with 15" wheels from the factory.  The M3 is not really a good comparison, because not much on that car is in common with the standard E30.  The M3 has 5-lug hubs and completely different suspension than the standard E30.  

 When you go up from 14" to 15" wheels, you have to change the size of the tire to keep the same (or close) rolling radius.  195/60/14's are factory tires, and I think the 15" wheels had 205/55/15 tires.  I'm not 100% on that though.

 I think the wheel option was for later E30's, probably 1988 and newer.

 If you want to go bigger than 15", you can always check on some Honda wheels.  There are FAR more wheel options for the Honda Civic than there are for the E30, so you can find good deals and an abundance of wheel designs.  They aren't really my style, but some people like them, and they have the same bolt pattern (4x100mm).  Make sure you check the offset, and backspacing to match.

 Good luck,
 Josh

Answer
Yes, it can seem confusing, but throw the M3 out, and it's strait forward.  Once again, the M3 is the only "odd-ball" of the bunch.  You can put the IX wheels on the 325i's, or vice-versa.  I think you can get away with 215 wide tires on an E30 without rubbing issues, but it will be extrememly tight.
 Look at the later 5-series, there is probably 10 different wheels offered from the factory for those cars.  The E36 is the same way.  The E30 just never got those options for some reason.  There are probably 4-5 wheels available for the E30 from the factory.  BBS makes some pretty good looking wheels for our cars, but they are more pricey than picking up a set of 15" originals.  The BBS wheels you are talking about are called "Basket-weave" wheels.  In Europe they had the same 15" Basket-weaves, except they had a larger, wider polished lip and they look really good.
 A company called Ronal makes the "LS" which is also for the E30, and they look great as well (probably my favorite besides the BBS RX's)
 
 If you want 5-lug, you can buy a whole M3 suspension although they fetch a pretty high price.  Then you could run latemodel wheels on your E30.  You can also take the rear suspension from an E36 318ti (hatchback) and put it under yours, and I think Z3 front suspension will bolt up, but the geometry takes some playing with to get it to fit right.  But you would have 5-lug suspension.

 So right now, you can check out TireRack.com, and select your car (E30) and they will show a list of wheels they carry for it.

 Good luck,
 Josh