Square setup on Z4M (four rear wheels)

[ed80]

Before I start shopping for summer tyres (while gazing out at the ice this morning), I wanted to consider a move to a square setup. I have had this on my last BMW (E46) and found that it improved the handling considerably. The easiest option seems to be 18x9 ET30 all round. This is the same as running four stock rear wheels, so I thought I would check if anyone else had done the same?

From what I can tell, it will lead to about 24mm more stick out at the front, with no basically change in the inner suspension clearance. I can swap one of my rears to the front to check exact fit, but first I wanted to see if anyone had experience with it.

My endgame would be to order a set of forged Apex wheels in this size, so it's hard to undo if it turns out to be a bad idea

 

[Mister T]

They're not going to fit without some work and you'll probably end up having to drop the tyre size which will make it a bit of a waste of time.

They'll stick out further than a 219/260 and they're already a tight fit on the front.

 

[ed80]

Yeah, I think you are right. I got a very comprehensive reply from Apex who have a fitment guy running 245/40/R18 all round on those wheels, and it's incredibly tight. I'll dig it out and post here later for posterity.

 

[Mr Tidy]

I can see the front being a problem. a 9J ET30 on the front would be like a 12mm spacer plus half an inch of rim.

Trying a 224 rear on the front might be the only way to be sure!

 

[enuff_zed]

I can see the front being a problem. a 9J ET30 on the front would be like a 12mm spacer plus half an inch of rim.

Trying a 224 rear on the front might be the only way to be sure!

Sound like I may be able to sell this set of negative spacers after all. :wink:

 

[axelleveau]

If you want to go with a brand new set of wheels from APEX, why not go for something like a 9J ET40-42 or maybe even a 8.5J and put 12-15mm of spacer at the rear? At the end of the day, even if the 224 9Js where OK at the front you would have front flush and rear tucked in so rear could do with spacer. From what I have seen on APEX website, they do something similar to run square setup on track E82/87.

 

[Ed Doe]

I'm running 8.5j ET35 fronts with 245/40 track tyres (so very square shoulder compared to road tyres); I only have minimal rubbing of the arch liners when on track.

M224 wheels are 9j ET30. Plugging that into willtheyfit.com brings up the following;


So not a million miles away - I'd say it'd be eminently do-able!

I don't have a clear picture of mine but the below might help give some idea of 'poke' - the M224 would basically be the same as mine with a 11mm spacer fitted if that helps visualise :lol:

 

[ed80]

I'm running 8.5j ET35 fronts with 245/40 track tyres (so very square shoulder compared to road tyres); I only have minimal rubbing of the arch liners when on track.

M224 wheels are 9j ET30. Plugging that into willtheyfit.com brings up the following;
224 vs ec7s.JPG

So not a million miles away - I'd say it'd be eminently do-able!

I don't have a clear picture of mine but the below might help give some idea of 'poke' - the M224 would basically be the same as mine with a 11mm spacer fitted if that helps visualise :lol:

The guy from Apex was running 245/40s on ET30 9J on his own Z4m, he said it was very close but just about ok with ~2 degrees of camber. I think I would squeeze in 245/40s but not 255/40s. I will try swapping wheels around and driving around the block to see if it works at all once the weather improves.

 

[enuff_zed]

I know you’d lose a bit of rubber on the rear, but what about running all front wheels, with spacers on the back?

 

[Dubbedown]

I run Square 224s as my track day rain setup. But it will come down to:

- tire model (how square the shoulders are)
- tire size (width and profile)
- alignment settings
- ride height

But assuming stock height, I think you’ll generally need -2.5 degrees of camber which honestly isn’t that aggressive imo. Removing strut pins + adding washers should get you pretty close.