2009 18" aftermarket wheel sizing

N

NCZ4

Member
Hi
Just ordered an 09 sDrive 30i, base model with 17 x 8.0 Star Spoke (Style 290) light alloy wheels and 225/45 run-flats (metallic black with red leather and wood). Don't love the wheels and looking for aftermarket 18" black wheel/tire combo.

So, far love the OZ 35th anniverary wheels (18 x 8.0) with 225/40/18 run flats.
http://www.tirerack.com/wheels/results.jsp?filterSize=All&filterFinish=All&filterBrand=O.Z.&filterSpecial=false&filterNew=All&autoMake=BMW&autoModel=Z4+sDrive30i&autoYear=2009&autoModClar=Base+Model&sort=Brand

Also like the Beyern mesh in black, but they are 18 x 8.5. Will they work in the front (all factory optional combos have 8 in the front and either 8, 8.5 or 9 in the rear)? Would they also take 225/40/18's and not rub? How can I be sure?
http://www.beyernwheels.com/BMW_wheels_beyern_typemesh.php

Thanks for any advice.
 
The standard specs for 18 wheels are -

8JX18 ET:29
81/2JX18 ET:40

So for the Beyern wheels I'd say get the 8.5" ET15 for the front (which *should* be OK) and the 8.5" ET40 for the rear.

Not sure the OZ wheels will fit on the front without spacers at ET40. Have a play here

:idunno:

Congrats on the order BTW :thumbsup:
 
Thanks
I still find that a little confusing but will try to confirm with local Beyern dealer.
Would I then go with 225/40/18 or 245/30/18? How do I know best tire size match?
 
Sounds good.
But couldn't I do 18 x 8.5 ET 40 with 225/40/18 all around and then be able to can rotate them?
Seems like on the calculator that ET 40 the best fit. Curious you recommend ET 15 for front?
 
You could if you wanted, but it might look a little under-tyred at the rear. As far as I can see ET40 is too much on the front with 8.5" wheels if the OEM wheels are 8.0" and ET29. GP20 knows all about offsets, maybe he will be along soon?
 
went with 10 x 8.5 ET 40 all around
and 245/40/18 all around
can now rotate and still have beefier tire
being shipped, but guaranteed to fit
 
Just go to a reputable aftermarket wheel and tire vendor website, like tirerack.com
They show many examples of 18 x 8.5 ET 40 recommended for Z4 front and rear fitment.
For example:

The Enkei Racing 18's:
Front and Rear Fitments
18x8.5
Offset: +40mm Backspacing: 6.25" Bolt Pattern: 5-120

Enkei Racing Performance 18's for Z4 even go up to ET 42mm

Overall, aftermarket 18's recommended for Z4 have offsets varying from 35 to 42, none near as low as 15.

I was more concerned about putting the 245's in the front as no one seems to be doing that. But my tire people assure me will be good.
 
Just a final note:
18 x 8.5 ET 40 fit fine all around, as do the 245/40/18 (only 5mm clearance between front struts and tires, but fine).
 
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