What size spacer for E36 wheels on an E30?

[tony92ic]

I picked up a set of early 17x7 M Contours.  Will I need spacers to make them work? And if I do what size should I try?

I assumed 20mm since e30s generally are 20mm offset and e36s 40mm, but I noticed BBS uses 40mm on its 17x7 for the e30. that would seem to indicate I may not need spacers at all.

Also do the 17" wheels make the ride unacceptably harsh? I am going to put them on my cabby so the chassis doesn't like it too stiff.  I am thinking about some high performance all seasons like the Kumho AST hoping that the sidewall will be a little softer than a pure summer tire. I have Kumho ASXs on it now (205/55/15) and really like the ride and handling. Nice compromise.

[Warsteiner]

Are these original E36 M3 M-Contours?

[DesktopDave]

I'm sure that the offset will have to change depending on wheel width.

Decent links:
http://www.maxbimmer.com/forums/showthread.php?t=54146
http://www.1010tires.com/WheelOffsetCalculator.asp

Someone else definitely knows better than I do, but I'd have to guess that each additional inch more than the stock 6" inch width would need ~13mm more offset (larger ET number) to keep from rubbing the strut.

I'm thinking out loud here, please correct me if I'm wrong:
Replacing the stock 14x6" et30 steelies with some 16x8" et30 rims would put about 25mm more on each side of the rim.  Less offset would push the rim out of the wheel well.  A 16x8" et20 would only have 15mm more depth but stick out 35mm more.

I keep measuring the fenders, strut housings and wheel liners to see what various wheel/tire combos would fit.  Maybe a 5-lug conversion with e34 or e38 wheels would be best.  Tire sizes give some flexibility too, but the offset is critical.  Spacers can help, but they're not a perfect solution, especially over 20mm thick.

I like the Kumho Ecsta ASXs too.  They are a nice compromise in a summer tire.  Barely all-season though; snow tires are the answer up here.

[4banger]

ive got 17x8.5's on my stratusR/T(stock size) and to be honest with those side walls under a inch and half tall it rides rougher than my 1 ton deisel truck.  when you start going with bigger rims the sidewall height drops and that makes the ride a bit harsher.

[DesktopDave]

+1 on that.  Last October I swapped my 55-series summer tires for 75-series winter tires and can't believe the difference in comfort at the same tire pressure.  OTOH handling is definitely much worse, and the snow tires are noisy too.