18" wheel sizes for z3m coupe

[sean.bmwm3]

Hi guys, I have just upgraded from a e36 m3 to my first z3m coupe and need some help regarding wheels. I want to fit a set of 18" BBS RGR (81/2" front and 10" rear) but have no idea on what off sets to go for or if I have to fit spacers!

[c_w]

I would say ET35 front and as close as ET10 you can get for the rear. Most aftermarkets only go down to around ET15-20 so you have to run small 10mm spacers on the rear.

I have run a 10J ET15 rear wheel with a 10mm spacer fine. Even without the spacer the wheel still sits out 5mm more than the OE wheel.

[coupe fan]

I have got BBS RSGTs. Looked up the old invoices.

18" x 8.5" 5 x 120 lugholes ET 38 offset
19" x 8.5" 5 x 120 lugholes ET 22 offset

My wheels are in basement storage at my garage so I cannot measure the spacers. The wheel supplier should include/know the correct spacers to put in the boxes for a ZMC. Tirerack did. You can always get the spacers later after trying the wheels on the car and judging what you need.

I seem to recall that they also put in longer (than OEM) bolts due to the spacers.

[c_w]

Yep definitely need longer bolts with any spacers (bar perhaps 3mm "clearance" spacers).

Most wheel "specialists" I have spoken to in the UK just don't understand the mixed offset issue with the Z3M and assume at best it is the same as the E46 M3. One place I enquired about said they could get 3-series wheels to suit the car and run a spacer at the back which but they don't understand that with 3-series offsets it would require about a 30mm spacer to sit right so not exactly ideal!

The Z3M is unique in BMWs (AFAIK) to have an such a "low" offset of ET8 for the rear wheels (the front offset is a "3-series" offset, so easy to suit). The closest offset to the rear is that of the 5-series (or E46 M3/CSL) which tend to be around ET20.

[sean.bmwm3]

Thanks for the help. I now have the head ache of ringing round suppliers for a good deal!