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17" ARC8 on Z4M

Alloy wheels and tyre discussion
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philipw
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17" ARC8 on Z4M

Post by philipw » Thu Apr 01, 2021 7:46 pm

So finally an update. I tried everything I could to find a set of 17s that would fit over the DB9 calipers but after submitting a drawing of them to Apex, there was no chance that they would fit within the barrel.

So I bought a set of 18s last November and just got round to fitting them today. Couldn't be happier with how they fit, did not have to go too extreme with front camber to make them fit with just 2 degrees up front. I think a 245 front tyre would clear the wheel liners but did not want to chance it at the time. Planning to put a set of 5mm spacers on the rear as the front track width is currently 20mm wider than the rear.

For alignment, I always go with toe out on the front for that crisp turn in and I have to say with cup 2 tyres, it is next level! Rear camber is 1.50 thanks to a set of ECS camber arms with a small amount of toe in as straight line high speed stability is compromised a bit with toe out on the front.
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08 Carbon Black M Coupe

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Ed Doe
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17" ARC8 on Z4M

Post by Ed Doe » Fri Apr 02, 2021 9:14 am

I was just about to post my wheel specs for comparison - although 8.5j front I'm contemplating spacers to increase the track, and have no issues with arch liner rubbing currently.

But now I've read to the end I see you've sorted it anyway - car looks absolutely fab! I assume you track it based on the geo, square setup and bbk?

Pic of mine - because Apex wheels are the best :lol:
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Carbon Black '07 M Coupe: Intrax 1k2 Coilovers, AP-Racing, Raybestos ST45s, Tillets, Schroth, Vibratechnic, Apex EC7, Strongstrut, Eventuri, H&S, RTD, 4.1FD :evil:
Silver Grey '06 3.0si Coupe - SOLD :(

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philipw
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17" ARC8 on Z4M

Post by philipw » Fri Apr 02, 2021 8:08 pm

Thanks Ed. I remember seeing your car last year at Redish and was impressed with the EC9 design but decided to go with the more common ARC8 style.

I went for 18x9" ET30 & 18x9.5" ET35 to get the concave look front & rear with 235/40/18 & 265/35/18.
Front track 1535mm & rear is 1519mm without spacers. Might leave it without rear spacers to leave the offset as the turn in is awesome but does highlight the limits of the Bilstein B12 suspension it has. When rapidly changing direction, roll is noticeable so an H&R anti roll bar kit & KW V3 will have to be the next mods!

Yep I have been using it for track work for the past couple of years, very simple modifications (B12, BBK with RSL29, vibra technics mounts, Gruppe M, RTAB limiters, ECS rear camber arms) so far as mods are expensive and preventative maintenance must come first! I found that sorting out the spring rates and fixing the geometry yielded the biggest benefits, standard geometry is set-up for understeer from my experience.
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17" ARC8 on Z4M

Post by Ed Doe » Sat Apr 03, 2021 8:27 am

philipw wrote: Fri Apr 02, 2021 8:08 pm Thanks Ed. I remember seeing your car last year at Redish and was impressed with the EC9 design but decided to go with the more common ARC8 style.

I went for 18x9" ET30 & 18x9.5" ET35 to get the concave look front & rear with 235/40/18 & 265/35/18.
Front track 1535mm & rear is 1519mm without spacers. Might leave it without rear spacers to leave the offset as the turn in is awesome but does highlight the limits of the Bilstein B12 suspension it has. When rapidly changing direction, roll is noticeable so an H&R anti roll bar kit & KW V3 will have to be the next mods!

Yep I have been using it for track work for the past couple of years, very simple modifications (B12, BBK with RSL29, vibra technics mounts, Gruppe M, RTAB limiters, ECS rear camber arms) so far as mods are expensive and preventative maintenance must come first! I found that sorting out the spring rates and fixing the geometry yielded the biggest benefits, standard geometry is set-up for understeer from my experience.
Ah yes, that would have been whilst my engine was in bits after the last trackday.... :lol: :cry:

I can't really complain as a lot of the mods on my car were done before I bought it, but I do wish the fronts were wider, the 8.5j just doesn't have enough concavity and I definitely reckon a 9j would fit (I'm sure the us boys are running 9j fronts with a bit of camber which again isn't an issue for me either!) Always loved the arc-8s and probably would have bought those out of choice (in bronze - I reckon they'd look ace on carbon Black!), but that being said, in the metal the ec-7s have grown on me.

The previous owners seem to have all spent small fortunes with centre gravity motorsport getting the car corner weighted and geo setup. To my tastes though there's still a little too much push, so I'm hoping to spend some time eventually finessing this aspect... Time is at a premium though at the moment with a 12week old baby now, so in the grand scheme I'm just grateful for the odd drive right now :lol:

You planning any trackdays this year? I'm hoping to get up to donny for an evening slot at some point late summer, subject to availability etc. Might pop onto a cheeky brands hatch day at some point too, again time permitting!
Carbon Black '07 M Coupe: Intrax 1k2 Coilovers, AP-Racing, Raybestos ST45s, Tillets, Schroth, Vibratechnic, Apex EC7, Strongstrut, Eventuri, H&S, RTD, 4.1FD :evil:
Silver Grey '06 3.0si Coupe - SOLD :(

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17" ARC8 on Z4M

Post by philipw » Thu Apr 15, 2021 10:58 pm

Ed Doe wrote: Sat Apr 03, 2021 8:27 am
philipw wrote: Fri Apr 02, 2021 8:08 pm Thanks Ed. I remember seeing your car last year at Redish and was impressed with the EC9 design but decided to go with the more common ARC8 style.

I went for 18x9" ET30 & 18x9.5" ET35 to get the concave look front & rear with 235/40/18 & 265/35/18.
Front track 1535mm & rear is 1519mm without spacers. Might leave it without rear spacers to leave the offset as the turn in is awesome but does highlight the limits of the Bilstein B12 suspension it has. When rapidly changing direction, roll is noticeable so an H&R anti roll bar kit & KW V3 will have to be the next mods!

Yep I have been using it for track work for the past couple of years, very simple modifications (B12, BBK with RSL29, vibra technics mounts, Gruppe M, RTAB limiters, ECS rear camber arms) so far as mods are expensive and preventative maintenance must come first! I found that sorting out the spring rates and fixing the geometry yielded the biggest benefits, standard geometry is set-up for understeer from my experience.
Ah yes, that would have been whilst my engine was in bits after the last trackday.... :lol: :cry:

I can't really complain as a lot of the mods on my car were done before I bought it, but I do wish the fronts were wider, the 8.5j just doesn't have enough concavity and I definitely reckon a 9j would fit (I'm sure the us boys are running 9j fronts with a bit of camber which again isn't an issue for me either!) Always loved the arc-8s and probably would have bought those out of choice (in bronze - I reckon they'd look ace on carbon Black!), but that being said, in the metal the ec-7s have grown on me.

The previous owners seem to have all spent small fortunes with centre gravity motorsport getting the car corner weighted and geo setup. To my tastes though there's still a little too much push, so I'm hoping to spend some time eventually finessing this aspect... Time is at a premium though at the moment with a 12week old baby now, so in the grand scheme I'm just grateful for the odd drive right now :lol:

You planning any trackdays this year? I'm hoping to get up to donny for an evening slot at some point late summer, subject to availability etc. Might pop onto a cheeky brands hatch day at some point too, again time permitting!
Oh dear, that is unfortunate! The top end is my next fear but if it goes then its an excuse to fit Shrick cams and maybe a carbon air box should funds stretch!

So far so good with the 9J on front, no rubbing with road driving but track use will highlight any issues. I was very tempted with the matte Bronze colour but wasn't brave enough to buy them as the penalty for not liking them would be severe! Hope you manage to get out on track at some point this year, I have Thruxton booked for June so looking forward to seeing how it drives with the lighter rims:)
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17" ARC8 on Z4M

Post by Ed Doe » Wed Apr 21, 2021 10:27 am

philipw wrote: Thu Apr 15, 2021 10:58 pm Oh dear, that is unfortunate! The top end is my next fear but if it goes then its an excuse to fit Shrick cams and maybe a carbon air box should funds stretch!

So far so good with the 9J on front, no rubbing with road driving but track use will highlight any issues. I was very tempted with the matte Bronze colour but wasn't brave enough to buy them as the penalty for not liking them would be severe! Hope you manage to get out on track at some point this year, I have Thruxton booked for June so looking forward to seeing how it drives with the lighter rims:)
Indeed it was a bit of a pain! Heyho, fully sorted now, so hopefully many miles of enjoyment to look forward to now!

I was the same - when it was apart I very very nearly plumped for Schrick cams, but with the surrounding investigative work required, financially it made more sense to put new OE Cams and the Schrick DLC Follower in and just enjoy as is. I convinced myself I didn't need ~375bhp anyway, and adding another £800 or so into the mix for a proper map wasn't sensible :lol: one day!!

Good to hear no rubbing on the front with the 9J, but just FYI, my 8.5J fronts did start to push the bumper on track I think - but then I'm running quite conservative front camber (and generally quite conservative Geo) - another thing I need to sort out!

I'll let you know how I get on with booking tracktime this year - enjoy yours! I do enjoy an evening session - quite pleasant having a few hours popping on/off the track to suit yourself in the late afternoon sunshine :)
Carbon Black '07 M Coupe: Intrax 1k2 Coilovers, AP-Racing, Raybestos ST45s, Tillets, Schroth, Vibratechnic, Apex EC7, Strongstrut, Eventuri, H&S, RTD, 4.1FD :evil:
Silver Grey '06 3.0si Coupe - SOLD :(

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