M3 Wheels on Z4?

SlikM · 03-21-2009, 04:02 AM

This seems like an obvious answer because of all the CSL's we see on Z4M's around here but can someone tell me if the OEM M3 E46 wheels (18's and 19's) all fit on the Z4M?

I tried a quick search but nothing specific, sorry if this is a repost.

AWM3 · 03-21-2009, 04:45 AM

Generally speaking they do fit, but there are minor differences. The M3 front wheel is the same width (8") but has an offset of 47, while the Z4M has an offset of 42. Therefore an M3 wheel will be 5mm closer to the strut (moved inward away from the fender) than the Z4M wheel. In certain situations, like with aftermarket coilovers, the M3 wheel might contact the strut or spring. Also, M3 wheels will narrow the front track by a total of 1cm (5mm on each side) which doesn't sound like much but it could change the handling slightly. Since there is already a lot of space between the fender lip and the wheel in front, the M3 wheels will exaggerate that and make it appear that there is too much space between the wheel and fender. Because of these considerations, many people use a spacer on the front with the M3 wheels. A 12 mm spacer with matching longer wheel bolts will move the wheel a net distance of 7 mm closer to the fender (12-5=7) which will restore any lost clearance on the inside and will reduce some of the unattractive gap between the tire and fender, as well as widenng the front track slightly.
In the back the situation is reversed. The M3 wheel is 9.5" wide with an offset of 26. The Z4M wheel is 9 inches wide with an offset of 30. So the M3 wheel gains 6 mm (1/4 inch) of width on the inside and the outside, but the wheel is moved 4 mm closer to the fender. So on the inside the wheel position is only 2 mm changed, while on the outside the wheel is 10 mm (6+4=10) closer to the fender. This is fine because there is plenty of clearance with the stock tire sizes. No spacer is used on the rear. When you start getting away from OEM tire sizes, that adds another set of numbers that have to be factored in.
Also keep in mind that many aftermarket E46M3 wheels did not have factory offsets, so before assuming such wheels will work on the Z4M, you have to check out the specifications.
Short version - use M3 wheels with a spacer on the front.

03-21-2009, 04:02 AM	#1
SlikM First Lieutenant 28 Rep 335 Posts Drives: '08 BSM/Blk M Coupe Join Date: Jan 2009 Location: Rancho Cucamonga iTrader: (2)	M3 Wheels on Z4? This seems like an obvious answer because of all the CSL's we see on Z4M's around here but can someone tell me if the OEM M3 E46 wheels (18's and 19's) all fit on the Z4M? I tried a quick search but nothing specific, sorry if this is a repost.
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03-21-2009, 04:45 AM	#2
AWM3 BMW Fan 11 Rep 553 Posts Drives: 2012 E92 M3, Alpine White Join Date: Apr 2008 Location: Georgia, USA iTrader: (0)	Generally speaking they do fit, but there are minor differences. The M3 front wheel is the same width (8") but has an offset of 47, while the Z4M has an offset of 42. Therefore an M3 wheel will be 5mm closer to the strut (moved inward away from the fender) than the Z4M wheel. In certain situations, like with aftermarket coilovers, the M3 wheel might contact the strut or spring. Also, M3 wheels will narrow the front track by a total of 1cm (5mm on each side) which doesn't sound like much but it could change the handling slightly. Since there is already a lot of space between the fender lip and the wheel in front, the M3 wheels will exaggerate that and make it appear that there is too much space between the wheel and fender. Because of these considerations, many people use a spacer on the front with the M3 wheels. A 12 mm spacer with matching longer wheel bolts will move the wheel a net distance of 7 mm closer to the fender (12-5=7) which will restore any lost clearance on the inside and will reduce some of the unattractive gap between the tire and fender, as well as widenng the front track slightly. In the back the situation is reversed. The M3 wheel is 9.5" wide with an offset of 26. The Z4M wheel is 9 inches wide with an offset of 30. So the M3 wheel gains 6 mm (1/4 inch) of width on the inside and the outside, but the wheel is moved 4 mm closer to the fender. So on the inside the wheel position is only 2 mm changed, while on the outside the wheel is 10 mm (6+4=10) closer to the fender. This is fine because there is plenty of clearance with the stock tire sizes. No spacer is used on the rear. When you start getting away from OEM tire sizes, that adds another set of numbers that have to be factored in. Also keep in mind that many aftermarket E46M3 wheels did not have factory offsets, so before assuming such wheels will work on the Z4M, you have to check out the specifications. Short version - use M3 wheels with a spacer on the front.
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