Buying new 18" rims to replace 17" I need help

carjul140 · Post by **carjul140** » Mon Jan 31, 2022 7:03 pm

Need help before purchasing these for a 2008 Z4 3.0si without sport suspension.
Front - 225/45/18 on 8J EH2+IS30 rims
Rear - 255/40/18 on 9J EH2+IS41 rims

Do you think these would fit without any rubbing issues? Or any other issues? Car has about 22,000 miles or 36,000 kms so close to stock height

True-Blue · Post by **True-Blue** » Mon Jan 31, 2022 7:55 pm

carjul140 wrote: ↑Mon Jan 31, 2022 7:03 pm Need help before purchasing these for a 2008 Z4 3.0si without sport suspension.
Front - 225/45/18 on 8J EH2+IS30 rims
Rear - 255/40/18 on 9J EH2+IS41 rims

Do you think these would fit without any rubbing issues? Or any other issues? Car has about 22,000 miles or 36,000 kms so close to stock height

Rears might be ok, fronts very unlikely to work

Mr Tidy · Post by **Mr Tidy** » Mon Jan 31, 2022 9:07 pm

Welcome to the forum by the way!

That size might work on the front. I fitted a set of E89 wheels to my 2nd 3.0Si Sport so M-Sport suspension and the fronts were 8Jx18 ET29 with 225/45 tyres and I didn't have any issues with rubbing. Rears were 8.5Jx18 ET40 with 255/40 tyres but I don't think another half inch would be an issue.

Hopefully this photo of the fronts fitted will give you an idea of how they looked.

carjul140 · Post by **carjul140** » Mon Jan 31, 2022 9:43 pm

Hi. Thanks for reply and photo. It helped a lot to visualize it. Our et and ture sizes are very similar. I don't have the sport suspension so the car sits a 1/2 inch higher than yours. I plugged in the sizes on one of the websites and it said that on my rears, it would push the rims inwards by 7.7mm and outwards by 17.7mm. I have lots of height in the rears, and about 25mm to the edge or the fender lip. So it should be fine for the rears. They also said that for the fronts it would push the rims inwards by 16mm and outwards by 16mm. Now thst makes no sense as the rims are 1 inch narrower and tires are 1.25 inches narrower. So it looks like the offset of 30 vs original 46 is impacting the way it sits. I still don't get it as I thought it would either affect it by pushing it inwards or outwards. Thanks again

Mr Tidy · Post by **Mr Tidy** » Mon Jan 31, 2022 11:46 pm

What did you compare to for the fronts? If it was a comparison with your 17s with less than 8J rims those 18s could sit further in and further out if that makes sense!

OE staggered 18s were 8Jx18 ET47 fronts so an 8Jx18 ET30 should just sit 17mm further out and plenty of people seem to have run 15mm spacers on the front.

OE staggered rears are 8.5Jx18 ET50 so your proposed 9J ET41s should be OK. I've seen quite a few 3.0Sis running 224s from the Ms and those rears are 9Jx18 ET30 so sit 11mm further out than what you are planning.

carjul140 · Post by **carjul140** » Tue Feb 01, 2022 1:41 am

My compariso was my 17x8 square setup with et46 as originally built from bmw. I feel the rear is not an issue. The fronts I'm not so sure. The rims I'm looking at are from an X1 E84, style 356 M rim. They weigh 1.85kg more than my style 201 rims. I hope they will work out

carjul140 · Post by **carjul140** » Tue Feb 01, 2022 10:16 pm

Thanks fir your help. I have an hour before deciding if I should buy these rims and tires. Your setup based on a 3.0 si is the best answer so far and makes me believe it should work on mine. So no rubbing at all, even when turning sharply and hitting a bump? Thanks again

Z4-forum.com

Z4-forum.com