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[Mandersm]

Hi guys

I`m planing to get a square set of ARC-8 for next year, and really want to get 245 to fit.
Will i get enough camber with M3 control arms and Dinan camper plates? I`m willing to roll fenders if I need to.

Setup I`m planing for (square):
Wheels: Apex ARC-8 - 8,5x18" ET45
Tires: PSS 245/35-18"
Car: 125i (128i)

I`m on the fence about if I want a square setup or wider rear wheels.
I want the car to have to have the absolute best handling and performance there is. So I want i light and strong wheel. And as I understand a square setup will give me this.

Can anyone tell me if Apex ARC-8 wheels are any good in quality, and can be driven "hard"?
The wheels I have now are no longer round (all four is ready for the bin), and this is after only to years of normal daily driving.

[Kgolf31]

APEX are designed to be beaten on. They can handle the forces, they are at track wheel.

They are my autox and track wheel

17x8.5 et40

[e36addict]

The setup you describe is the exact setup I used to run.. Worked great. Only suspension mod was ST coils.. No camber plates, no roll in the rear. Never rubbed at all.

[WillisW555]

That's the setup I'm planning to use as well. Good to hear about Apex's durability.

[Expert@ApexWheels]

We're glad to hear such positive feedback of our wheels! The ARC-8's can surely be used as a track wheel and has been proven to be able to take track abuse from track cars and race cars around the world. The 18x8.5" ET45 squared is a very popular fitment for those that are looking for a direct fitment with 235/40/18 sized tires, though the 245/35/18 tires would require a small spacer and some negative camber up front. The negative camber in front can be achieved by either installing M3 control arms, or camber plates.

[SamN]

David - is there a square setup with 17's that will work (arc-7/8)? Thx!

[chris82]

Apex are among the best wheel out there for track use (or street of course). Affordable, light, strong, durable, specific offsets for each application. I had a set of arc8s myself, such a great wheel! So many teams runs them in the BMW crowd and I honestly have never heard a negative about them on any of the bimmer forums

[Kgolf31]

Originally Posted by SamN

David - is there a square setup with 17's that will work (arc-7/8)? Thx!

There is, but you're running a more aggressive offset.

Instead of ET45, you're running ET40. I run it, you just need camber and rolled fenders to fit the tires front/rear

[Expert@ApexWheels]

Originally Posted by SamN

David - is there a square setup with 17's that will work (arc-7/8)? Thx!

We have 17" ARC-8's available, but the EC-7's do not come with a 17" option. We do not have an ARC-7 wheel, so I'm guessing that you meant to say EC-7's. With camber plates and M3 arms, you can get our 17x8.5" ET40 ARC-8's wheel to fit up front. That can be used with either 245/40/17's or 255/40/17's. The back of the car will be a problem, but the front of the car will have some rubbing. Using the 17x8.5" ET40 even with a 245/40/17 in the rear will rub without fender rolling. This is due to the car having unusually high rear offsets (the stock 8.5" wheel has a 52mm offset). The 1-series racers run our 17x8.5" wheel with 255/40/17 square, but they were willing to mess with the rear fenders beyond just a simple roll.

Our 18" 1-series wheel is 18x8.5" ET45 for both the ARC-8's and EC-7's, which is an easier rear fitment in the rear due to being in 5mm more, but even at this offset rubbing can occur, so a rear fender roll is recommended. The 245/35/18 is the recommended tire size. A 245/40/18 is far too tall for the car and would cause tire rubbing on the fenders. The 255/35/18 tires can fit up front on the 8.5" ET45 wheel but a thin 5mm spacer may be needed in addition to camber plates being needed for all these listed fitments. 255/35/18 would be very aggressive on the rear at that offset, so messing with the fenders would definitely be needed.

[feeshta]

Originally Posted by e36addict

The setup you describe is the exact setup I used to run.. Worked great. Only suspension mod was ST coils.. No camber plates, no roll in the rear. Never rubbed at all.

I know I'm a little late to the party here, but did you have the front fenders rolled? David from Apex is saying that this steup will not fit in the front without some modification, so I am a little confused.

[Expert@ApexWheels]

Originally Posted by feeshta

I know I'm a little late to the party here, but did you have the front fenders rolled? David from Apex is saying that this steup will not fit in the front without some modification, so I am a little confused.

The 18x8.5" ET45 setup is the one ran by the user that you've quoted, and that does not require modifications with a 235/40/18 tire. A 245/35/18 sized tire would need either camber plates or M3 control arms and a small spacer to ensure adequate fender and strut clearance. There may be certain street tires that may get away without needing those, but it's very rare, and we like to recommend fitment advice that would be guaranteed to fit without problems for the majority of the tire choices available.

[Kgolf31]

Originally Posted by David@ApexRaceParts

The 18x8.5" ET45 setup is the one ran by the user that you've quoted, and that does not require modifications with a 235/40/18 tire. A 245/35/18 sized tire would need either camber plates or M3 control arms and a small spacer to ensure adequate fender and strut clearance. There may be certain street tires that may get away without needing those, but it's very rare, and we like to recommend fitment advice that would be guaranteed to fit without problems for the majority of the tire choices available.

Basically dead on with what David said.

ARC8 Fitments are not optimal. APEX isn't going to come out and say "Yes, the wheel will fit without issues" Because well, that isn't the case.

I run 17x8.5 ET40 and run 5mm spacers up front with fenders rolled on a 245/40/17 Hankook RS3 tire to make it fit. Heavy camber (-3.6*) upfront too

[Bimmer-Bob]

Originally Posted by Kgolf31

Basically dead on with what David said.

ARC8 Fitments are not optimal. APEX isn't going to come out and say "Yes, the wheel will fit without issues" Because well, that isn't the case.

I run 17x8.5 ET40 and run 5mm spacers up front with fenders rolled on a 245/40/17 Hankook RS3 tire to make it fit. Heavy camber (-3.6*) upfront too

FWIW, I run the exact same wheels with 245 series Dunlop ZII's, and no spacer is required. Strut clearance is extremely close, however, but no problems with rubbing (even under load).

[FrankSz]

I've been wanting to pull the trigger on a square ARC8 18x8.5 setup for track days on my 128i, but all that I have read on this and other forums does not make sense, and APEX has been no help.

I have a staggered set of Style 263 wheels with Bridgestone Potenza RE050A runflats and a staggered set of Style 264 wheels with Michelin Pilot Super Sports. Both rears are 18x8.5 ET52 with 245/35R18, and I have tried both rears on the front with a 12mm spacer, effectively an ET40. Both fit identically, with 7mm clearance between the wheel lip and the strut. The "curb rash" protection ring on the tires both protrude 5mm past the wheel lip, leaving 2mm clearance between the tire and the strut. I chalked the strut and did a gentle run around the block, all the chalk was taken off by the tire, no issue with the wheel. I then drove it hard slalom in a parking lot, no fender rubbing, only strut. So how is it possible for any 18x8.5 ET45 to work? This would put the wheel 2mm from my strut, guaranteed rub on hard driving, never mind the complete interference with the tire. Ultimately I believe it comes down to the fact that all offsets are not created equal. Offsets are supposed to be the distance from the center line of outside of the wheel lips to the hub mounting surface. I bought a set of RTX Mystique 18x9 ET42 for the rears, they rubbed the fenders even after I had them rolled and 2 deg negative camber. I checked the offset, it was actually ET37, put it 5mm closer to the fender than it should have been and explains the rubbing.

So, the only true way I can see to ensure a perfect fit is by the backspacing dimension. Based on my stock Style 263/264 18" diameter wheels, I have exactly 168mm from the hub mounting surface to the strut, so I need an 18x8.5 wheel with a backspacing of about 158mm so the tires are 5mm from the strut. So I asked APEX, what's the backspacing? Reply: "Unfortunately we do not have backspacing measurements, but I do believe there is a way for you to convert the offset to the backspacing. We do not have that formula readily available." You're kidding, right? You do build these, don't you? From a drawing with dimensions, I would hope. At least you could pull one off the shelf and take a measurement for a sale.

Which brings me to my question for the forum members, does anyone have an ARC8 18x8.5, either ET38 or ET45, that would be willing to measure and post the backspacing (hub mounting surface to the outside of the inner wheel lip)?