235 in rear, or 255 up front

[joeybananaz18]

I'm looking to grab a set of Arc-8s the next time they have a group buy and just need a bit of help deciding out what route I should take. Here are my parameters:

1. Must be 18 inch wheels as I am looking to reuse my tires, which are Michelin Pilot Super Sports.
2. Must be square as I want to be able to rotate my tires.
3. Must be finished in their matt bronze finish (thanks to nextelbuddy for convincing me how sexy they look)
4. Must be able to retain the fairly comfortable ride I've become accustomed to.
5. Must be able to keep this relatively affordable so i would like to use either my front (235/40/18) or rear (255/35/18) tires and just buy 2 more tires to complete the set.

BONUS: I love the concavity look, but in order to obtain that I would need to go with an 18x9 et30 wheel. Rear won't be a problem but I don't know to what extent I would have to modify the front.

I am not lowered an would be ok with having to run a spacer if clearance would be an issue. I don't want to but would be ok with rolling my fenders. I already have what I believe is a "safe" route planned: 18x8.5 et38 all around wearing 235/40/18. So I figure if I can't make all those requirements happen, I know what I'll be settling on. But if I can make the 18x9s work without ruining my ride, I wouldn't mind trying it out.

So, what I'm wondering I can anyone recommend a set up that will make 1-5 and the Bonus all work on my car. I'm curious to see what scenarios the experts come up with to show trade offs.

Joe

[ZHPizza]

18x9.5 et35 with the 235's should be alright. Might have to roll the rears.

Edit: see here http://www.zhpmafia.com/forums/showthread.php?19220-Zhpe30abe-s-Project-Thread/page9

[joeybananaz18]

If he did 9.5s with 235, do you think I could get away with 9s and 255 up front? Or is that too much shoulder for the fronts?


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[downshift]

Hey Joe, you may have it a little backward front vs rear. The rear will require a LOT more modifications to the fenders to fit a certain width and offset wheel.

Unfortunately, you don't have many options here, given your level of comfort modifying your fenders. Requiring deep concavity, and an 18 inch wheel, limits you even further. 18x9.5 et38 would be a very aggressive fitment, I believe it is within 1mm of my fitment, both radially and axially (tire size and track width/position laterally out from the axle). You will not achieve this fitment without rolling your fenders close to their limit, which can also damage paint locally. This is the route I took, and I am unbelievably happy with the results, but it sounds like you are not interested in going this route.

I think you should figure out what is most important to you; you will have to compromise somewhere!

[joeybananaz18]

Sorry if there's confusion but I'm not at all looking to go 9.5, just 9. Does that give me more options?


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[slater]

I am not lowered an would be ok with having to run a spacer if clearance would be an issue. I don't want to but would be ok with rolling my fenders. I already have what I believe is a "safe" route planned: 18x8.5 et38 all around wearing 235/40/18.

that is definitely the safe, and correct, choice. i run 18x8.5 ET38 ARC-8s with 245/35/18 michelin PSS, and a 3mm spacer in the rear, and it rubs in the rear with passengers sometimes.

BP runs an 18x8.5 ET35 BBS CH setup, with 255/35/18s and mildly rolled rear fenders, and i believe he had some occasional rubbing issues in the rear.

rubbing sucks.

[cornercarver]

that is definitely the safe, and correct, choice. i run 18x8.5 ET38 ARC-8s with 245/35/18 michelin PSS, and a 3mm spacer in the rear, and it rubs in the rear with passengers sometimes.
Something in your numbers doesn't seem right - not that I'm challenging you. Just trying to understand fitments because I'm hoping to buy a set of Sportline 8s' next year and want to make sure I get the right sizes/offsets.

If the OEM rear offset with a 18x8.5 wheel is ET50, why would you move the new 18x8.5 wheel outboard with an ET38 offset? I checked mine and saw at least 1/2" clear between the tire and the shock. Moving a 8.5" wheel out by 12mm seems unnecessary if it's the same width as stock, especially if you've gone down in tire size to a 245. If you were increasing the width of the wheel to, say, 9.5", THEN you'd need to move it outboard to keep it in the same relative position to the shock. Seems like there's also plenty of space between the tire and fender lip to move it out 1/2" without rubbing.

What am I missing? If you were rubbing with a wider wheel and a 275, then I'd understand.

[downshift]

Something in your numbers doesn't seem right - not that I'm challenging you. Just trying to understand fitments because I'm hoping to buy a set of Sportline 8s' next year and want to make sure I get the right sizes/offsets.

If the OEM rear offset with a 18x8.5 wheel is ET50, why would you move the new 18x8.5 wheel outboard with an ET38 offset? I checked mine and saw at least 1/2" clear between the tire and the shock. Moving a 8.5" wheel out by 12mm seems unnecessary if it's the same width as stock, especially if you've gone down in tire size to a 245. If you were increasing the width of the wheel to, say, 9.5", THEN you'd need to move it outboard to keep it in the same relative position to the shock. Seems like there's also plenty of space between the tire and fender lip to move it out 1/2" without rubbing.

What am I missing? If you were rubbing with a wider wheel and a 275, then I'd understand.

It's because it looks better and still doesn't rub

[BCS_ZHP]

Know you want square, know you want 18’s, anyway here’s some measurements on 19’s and they rode on multiple ZHPs, both stock & lowered suspensions. Go to willtheyfit.com and type in the below data compared to what you want to see if it’ll fit. Fronts had no issues, rears were close but no fender rolling required.

19" staggered VMR 710s
- front 19 x 8.5 with 35 mm off set & 235/35-19 tires
- rear 19 x 9 with 40mm offset & 265/30-19 tires

[BCS_ZHP]

And here’s what that setup looks like with stock suspension

http://www.zhpmafia.com/forums/attachment.php?attachmentid=14125&d=1400983634

[BCS_ZHP]

And then lowered on PSS-9’s

http://www.zhpmafia.com/forums/attachment.php?attachmentid=15075&d=1407671004

[Vas]

I been wanting 19" Apex arc8 since Bruce said they are a great fit.

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[slater]

Something in your numbers doesn't seem right - not that I'm challenging you. Just trying to understand fitments because I'm hoping to buy a set of Sportline 8s' next year and want to make sure I get the right sizes/offsets.

If the OEM rear offset with a 18x8.5 wheel is ET50, why would you move the new 18x8.5 wheel outboard with an ET38 offset? I checked mine and saw at least 1/2" clear between the tire and the shock. Moving a 8.5" wheel out by 12mm seems unnecessary if it's the same width as stock, especially if you've gone down in tire size to a 245. If you were increasing the width of the wheel to, say, 9.5", THEN you'd need to move it outboard to keep it in the same relative position to the shock. Seems like there's also plenty of space between the tire and fender lip to move it out 1/2" without rubbing.

What am I missing? If you were rubbing with a wider wheel and a 275, then I'd understand.

going to a lower offset wheel, say ET38, increases the track width by 24mm.

and i run the 3mm spacer on the back to bring the square wheel setup offsets 'in line' with the stock ratio (so i effectively have increased track width in the rear by 30mm, and 30mm in the front).

in a perfect world i would run 9's or 9.5's in the rear on a 265/35/18, and one day i might, but i would have to run the 18x9.5 ET58 ARC-8s to avoid running into fender clearance issues... but then i might have shock clearance issues, so i'd likely need to run a 10mm spacer... i haven't measured yet. i do run into traction problems with the 245's in the rear, especially with the LSD, because it makes me do stupid stuff. otherwise 245-width PSS' are totally adequate for 235hp. :)

[cornercarver]

going to a lower offset wheel, say ET38, increases the track width by 24mm.

and i run the 3mm spacer on the back to bring the square wheel setup offsets 'in line' with the stock ratio (so i effectively have increased track width in the rear by 30mm, and 30mm in the front).

in a perfect world i would run 9's or 9.5's in the rear on a 265/35/18, and one day i might, but i would have to run the 18x9.5 ET58 ARC-8s to avoid running into fender clearance issues... but then i might have shock clearance issues, so i'd likely need to run a 10mm spacer... i haven't measured yet. i do run into traction problems with the 245's in the rear, especially with the LSD, because it makes me do stupid stuff. otherwise 245-width PSS' are totally adequate for 235hp. :)
Got it.:thumbsup

I hope to do the LSD eventually... Just not in the budget now though. With the recent Hotchkis F&R bar upgrades I can break the rear loose with a little throttle, so I think an LSD and some wider rubber (275mm) in the rear will round the car out nicely. The trick will be getting the right combination of offset and fender rolling to make it work. I predict a 9.5" wheel at ET38 should clear the shock and fender with a little fender rolling. This is on a non-lowered vehicle, of course.

[slater]

Got it.:thumbsup

I hope to do the LSD eventually... Just not in the budget now though. With the recent Hotchkis F&R bar upgrades I can break the rear loose with a little throttle, so I think an LSD and some wider rubber (275mm) in the rear will round the car out nicely. The trick will be getting the right combination of offset and fender rolling to make it work. I predict a 9.5" wheel at ET38 should clear the shock and fender with a little fender rolling. This is on a non-lowered vehicle, of course.

on a non-lowered vehicle, i think a 9.5" ET38 wheel would stick out past the fender. i think. :) that said, it's an incredibly aggressive fitment, lowered or not - and mega fender rolling would be required. i am going to be doing some very minor fender rolling to allow my 8.5" ET35 wheels to fit without rubbing - imagining another 12.5mm with wider rubber sticking out... no way would it work (for me). :)

[cornercarver]

Sorry - don’t know why I wrote ET38. I meant ET45 for a 9.5” wheel in the back.

[ZHPizza]

Here's another dude that pulled off the 18x9.5 et35 nicely by rolling the rear fenders and trimming the plastic tab:

http://www.zhpmafia.com/forums/showthread.php?16479-Zach-s-04-Imola-quot-Timeless-quot

a little pokey in the front but not bad

https://farm2.staticflickr.com/1630/25962829471_3f20b4a1be_b.jpg

[slater]

Here's another dude that pulled off the 18x9.5 et35 nicely by rolling the rear fenders and trimming the plastic tab:

http://www.zhpmafia.com/forums/showthread.php?16479-Zach-s-04-Imola-quot-Timeless-quot

a little pokey in the front but not bad

https://farm2.staticflickr.com/1630/25962829471_3f20b4a1be_b.jpg


yep, he was running 235's if i remember correctly. and flattened the inner rear fender lip? what's the point of going to a 9.5" wheel, other than looking cool, if you're running less rubber? it does look cool - for sure. but definitely form over function... and that kind of setup is not for me. ;)

[ZHPizza]

yep, he was running 235's if i remember correctly. and flattened the inner rear fender lip? what's the point of going to a 9.5" wheel, other than looking cool, if you're running less rubber? it does look cool - for sure. but definitely form over function... and that kind of setup is not for me. ;)I actually prefer it for the sidewall stability!

I have a 235 on a 9.0" wheel now, but since it's a pretty wide tread tire, there's little to no stretch. I like a small stretch so that I can use a softer sidewall tire for highway comfort and still have a stable sidewall for cornering. I'd definitely like to put these same tires on a 9.5" wheel.

[Vas]

As far as I recall, the only way to get the concave look with the Apex Arc8 was to run the 9.5" width wheels with an et35. And a 235 section tire provided enough clearance with the fenders rolled/pulled/cut.

Now apex offers the arc8 in a 18x9 et30 with a concave face but even with that size you still have to do some work to make them fit and not rub.

[Sockethead]

I'm running stock tire size and 9.0" ET 35 in the back. pretty aggressive roll on the fender and lowered... rubs on the plastic tab over big bumps... the thing that makes a lot of difference is the tire itself. Definitely different brands of the same size tire have different widths. Also, the more negative camber your running in the back, the more clearance you'll have.

[joeybananaz18]

I'm running stock tire size and 9.0" ET 35 in the back. pretty aggressive roll on the fender and lowered... rubs on the plastic tab over big bumps... the thing that makes a lot of difference is the tire itself. Definitely different brands of the same size tire have different widths. Also, the more negative camber your running in the back, the more clearance you'll have.

Sorry I've been MIA since i made this thread. Are you lowered at all? I'm looking to stay at stock height.

[704sw]

Not sure if it’ll help you, but for the sake of giving you more numbers to compare:

18x8.5 ET30 (225/40) did not rub until I lowered it. Now it only rubs on VERY deep compression. I’ll be backing off to ET35.

Rears are 9.5 ET42 (255/35) and haven’t rubbed once since lowering the car. I’m going to push them out to ET40 for experimentation.

[joeybananaz18]

Just a little update. Ive decided to take the safe route and go with 18 x 8.5 et38 all the way around. I figured i know it'll work without through any extra money at it and it will add toward the OEM+ look I'm going for. The real bonus was that i picked up a 5th wheel so i'll be able to run a full size spare.

[Reasoned1]

I have 18" x 8.5" ARC-8's (ET38) with 245/40 PSS' on my 2004 330i ZHP, and they fit good and ride fine--nicely balanced and slightly less tramlining than stock. I'm not lowered (although I could) and wanted a slightly beefier sidewall to protect my wheels, fill out the wheel wells, and correct my speedo. I stuck with 8.5 to play it safe and, because I think that's optimal enough for performance--not to mention they were on sale for 25% off.

[joeybananaz18]

I have 18" x 8.5" ARC-8's (ET38) with 245/40 PSS' on my 2004 330i ZHP, and they fit good and ride fine--nicely balanced and slightly less tramlining than stock. I'm not lowered (although I could) and wanted a slightly beefier sidewall to protect my wheels, fill out the wheel wells, and correct my speedo. I stuck with 8.5 to play it safe and, because I think that's optimal enough for performance--not to mention they were on sale for 25% off.

THIS. It seams like 245 is the ideal tire width when going square on 8.5s. Im going to through 235s on there. I know I'm encouraging oversteer by going square and with a narrower tire than stock but its not like it'll be uncontrollable, right?

[Reasoned1]

I think they'll handle beautifully and further minimize annoying tramlining.

[ZHPizza]

THIS. It seams like 245 is the ideal tire width when going square on 8.5s. Im going to through 235s on there. I know I'm encouraging oversteer by going square and with a narrower tire than stock but its not like it'll be uncontrollable, right?

I have 235 square and love it. Much easier to throw the car around.

[ELCID86]

I have 235 square and love it.

Ditto.

[joeybananaz18]

I think they'll handle beautifully and further minimize annoying tramlining.

Believe it or not, aside from price this was a big reason for going this route. The PSS seem to be prone to inducing a bit of tramlining. That and I need an alignment lol.
Thanks to all for putting my concerns to rest!


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[johnrando]

I do 245/35 18x8.5 square just to throw more numbers out there for you.


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[downshift]

i went 235 square and got rid of them within a month to replace with 255 square. the difference is unbelievable.

17x9 et30 255/40 square

[Reasoned1]

As another interesting datapoint, I run 205/50's on my 330xi's with Michelin Premiers, and they handle great, too--firm in the turns and no tramlining whatsoever. Plus, they're that much lighter. Sounds like sacrilege, but I am hard-pressed not to prefer them. It just goes to show that losing a little tire width isn't the end of the world.

[joeybananaz18]

i went 235 square and got rid of them within a month to replace with 255 square. the difference is unbelievable.

17x9 et30 255/40 square

Can I ask why you switched so fast?


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[ZHPizza]

Can I ask why you switched so fast?


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track rat needed moar grippy bitz

[Reasoned1]

Of course, I don't race or even track...

[joeybananaz18]

track rat needed moar grippy bitz

I wouldn't blame him for that. The PSS have more grip than I'm ever willing to play with. I just want to reduce the tramlining.


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[downshift]

I wanted slightly more grip, but mostly I wanted a larger thermal ballast + larger dissipation area. I was melting tires on the track left and right, but mostly because I ran some PSS and they are great street, but awful track tires. Funny how fine the line is. I run RE-71R 255 and the grip is pretty high.

I just thought 255 was the ideal balance of weight and width. Anything wider kind of turns into a "who's is bigger"contest with minimal performance gains

[joeybananaz18]

I wanted slightly more grip, but mostly I wanted a larger thermal ballast + larger dissipation area. I was melting tires on the track left and right, but mostly because I ran some PSS and they are great street, but awful track tires. Funny how fine the line is. I run RE-71R 255 and the grip is pretty high.

I just thought 255 was the ideal balance of weight and width. Anything wider kind of turns into a "who's is bigger"contest with minimal performance gains

I just went through your build thread. When I saw rear seat get taken out, I said to myself "yea this guy definitely needs more than 235" lol

[downshift]

I just went through your build thread. When I saw rear seat get taken out, I said to myself "yea this guy definitely needs more than 235" lol

Well I'm glad SOMEONE looked at it ;)

MCS dampers coming soon

[slater]

Well I'm glad SOMEONE looked at it ;)

MCS dampers coming soon

haha.... i read it a while back.

what spring rates are you going with?

also, you should check out FCM (Fat Cat Motorsports) for dampers. i'm reeeeeally thinking of going that route with my Touring.

what else are you running for suspension? it's easy to ruin it, for sure, but i can't say enough good things about the spherical RTABs. it's just.... connected.

i also noticed you had some reinforcement work done in the rear - what exactly was done? (and by TMS?) does your cage tie into the rear subframe mount points? does it also tie into the frame rails?'

sorry, i should've posted this in your build thread.

[sum1orotha]

Here are those concave 18" ARC 8s squared finished in Bronze [emoji51] http://www.m3forum.net/m3forum/showthread.php?t=594957

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