Square Roadstar Setup (Z3 M RDSTR)

[cutthegordian]

Thanks for looking,

Z3 M Beginner here. Bare with me, thanks.

To start, if you know/have a thread discussing a square setup on a z3 M (Roadster/coupe) using rear M ROADSTAR rims all around (excuse the redundancy in this thread) that would be great. As i could not find one on Maxbimmer/bimmerforums/roadfly.. etc.

Goal: I'm looking to find some information about using two sets of rear Roadstars (all around), for a track setup.

Stock Offset/Setup
Front 17x7.5: +41
Rear 17x9 +8

Inquiry: x4 17x9 (+8 all around).

Note: Currently the roadster is running FRONT 15mm spacers and REAR 20mm spacers in the back (my somewhat ugly aesthetic setup ). I've done some testing on the track, and believe the car can do better.

Spacer Reasearch

From my understanding, to obtain track optimization on the z3m a square setup is ideal. However, to do this setup i need FRONT 5mm spacers and REAR 30mm spacers. confirm/deny

My Z3 M Ride Height
Currently I have H&R suspension/coilovers and recently purchased Ground control camber plates. What ride height would be ideal?

Last but not least, i plan on combining this setup with 255/40 (17) Michelin Pilot Sports.

I'm learning here, and any insight/intel/knowledge would be helpful. So thanks for your input!

I hope myself and other Z3 owners can use this thread as a reference to this topic. Thanks.
-CTG

[kornfeld]

Assuming you also have 225/45 tires up front, when you plug your numbers into willtheyfit.com:

http://www.willtheyfit.com/index.php...set2=8#content

You get that the outer edge of the front tire will be moved outboard a whopping 52 mm. I'm no expert in this area, but I have a hard time believing you could get this to fit under the front fender/hood without absolutely insane levels of camber, which wouldn't be so good for handling or tire life. It will also move the scrub radius way out of whack.

If you google for things like "max width z3 front tire" and similar terms, you'll find relevant threads.

[jbrannon7]

Roadstars are really heavy (25lbs). Why re invent the wheel? Just do what every one else does and get 17x9 e36 light (16lbs) wheels all around. Like in my sig.

[BMWBergy]

Last but not least, i plan on combining this setup with 255/40 (17) Michelin Pilot Sports.

In addition to all of the above, to get the 17x9 ET8 wheel to 'fit' up front will require a good deal of camber (from lowering, plus plate adjustment) and the tire will need a little bit of 'stretch' to the sidewall (like a 235/40, MAYBE a 245/40). A 255/40 17 seems waay too tall and 'beefy' to fit comfortably.

[E.Hands]

Here are my roadstars with 255/40-17 on front:
http://www.bimmerforums.com/forum/sh...rs-v1-0/page28

[khammack]

Mine also has 255/40-17 all around with 17x9 SSR wheels. Running stock (or close to it) camber up front while on the street.

[BMWBergy]

Here are my roadstars with 255/40-17 on front:
http://www.bimmerforums.com/forum/sh...rs-v1-0/page28

Interesting. Any front shots with the wheels straight to show the poke? I've edited my above post to soften the language, since you've obviously mounted up the OP's intended combination. I do note some substantial rub marks on your tire shoulder/sidewall, however.

- - - Updated - - -

Mine also has 255/40-17 all around with 17x9 SSR wheels. Running stock (or close to it) camber up front while on the street.

What offset are the SSRs? I'm not suggesting that a 255/40 won't work on a 17x9" wheel (heck, that's what I have on my rear Roadstars), just that it seems too much to comfortably (yes, that's often a subjective determination) fit a 255/40 on the 17x9" ET8 wheel mounted on the front of a Z3/Z3M.

[khammack]

What offset are the SSRs? I'm not suggesting that a 255/40 won't work on a 17x9" wheel (heck, that's what I have on my rear Roadstars), just that it seems too much to comfortably (yes, that's often a subjective determination) fit a 255/40 on the 17x9" ET8 wheel mounted on the front of a Z3/Z3M.

SSRs are something like 45 offset with huge spaces. They came off of one of Will Turner's M3 race car. I agree with your comment about the ET8 on the front. I don't think they will work with any size tire.

[SunzOut]

17x9 square setup is pretty easy with 255/40 tire. Camber plates help, and you can't go supper low but certainly much lower than stock.

But trying to do it with the stock Rear 9" is just not a sensible option. I have a final offset of around 35 to 40 mm (41 to 45mm rim offset - 5 or 10mm spacer). the the 9mm Stock rear offset is going to push that wheel out by around an inch, so yes it may fit, but you need a either

1) much higher ride height
2) skinny 225 stretched
3) put up with rubbing when you do anything...

[z3papa]

255/40-17's are the answer on 17x9 wheels. My preference is to Apex variety but you can get some lightweight wheels from Enkei. I had a set of SSR's for a while which are nice but they are prone to bend and are very, very difficult to replace.

[khammack]

I had a set of SSR's for a while which are nice but they are prone to bend and are very, very difficult to replace.

I acquired mine around 2002 or 2003 and got 5 at the time, all used. One was bent but I was able to have it fixed. Since I have a spare, I'm not concerned about replacements (at this time ).

[BMWBergy]

I acquired mine around 2002 or 2003 and got 5 at the time, all used. One was bent but I was able to have it fixed. Since I have a spare, I'm not concerned about replacements (at this time ).

I have four SSR 'Type C' (Comp). 17x8" (ET35?) and 17x9.5" ET15. Very light and can clear a Willwood 332mm BBK.

[khammack]

I have four SSR 'Type C' (Comp). 17x8" (ET35?) and 17x9.5" ET15. Very light and can clear a Willwood 332mm BBK.

I think mine are type H.

[jbrannon7]

I am running D Force 17x9 wheels with 255/40-17 tires with a 42mm offset (standard E36) all around and H&R 30mm spacers in the rear with 12mm spacers in the front. I can move the wheels front to rear that way. I also have a set of D Force 18x10 wheels with 285/30-18 tires for the rear and I add a 5mm spacer as well as the 30 in the rear to keep them from rubbing the inner liner. I run the larger rear tires when I not running SCCA events.

[TurboBimmer]

17x9 square setup is pretty easy with 255/40 tire. Camber plates help, and you can't go supper low but certainly much lower than stock.

But trying to do it with the stock Rear 9" is just not a sensible option. I have a final offset of around 35 to 40 mm (41 to 45mm rim offset - 5 or 10mm spacer). the the 9mm Stock rear offset is going to push that wheel out by around an inch, so yes it may fit, but you need a either

1) much higher ride height
2) skinny 225 stretched
3) put up with rubbing when you do anything...

Does that mean that the full travel of the suspension is not usable with a 255?
With sticky tires and G force, the suspension will compress near it's full travel, so that means the tire will touch the body? I wouldn't like that to happen on a track.

Is this problem causes by a non ideal offset? Or all 255s rub?

[Scarceas]

Interesting. Any front shots with the wheels straight to show the poke? I've edited my above post to soften the language, since you've obviously mounted up the OP's intended combination. I do note some substantial rub marks on your tire shoulder/sidewall, however.

I'm not 100% sure but I don't think Ed managed 255 front roadstars the way OP is suggesting... Instead of rears mounted up front, I was thinking he had fronts widened so that the offset was a more natural fit.

[E.Hands]

I'm not 100% sure but I don't think Ed managed 255 front roadstars the way OP is suggesting... Instead of rears mounted up front, I was thinking he had fronts widened so that the offset was a more natural fit.

Exactly right. The rub marks were on the rears from running too much spacer (25mm) before rolling the fender lips.

[SunzOut]

Does that mean that the full travel of the suspension is not usable with a 255?
With sticky tires and G force, the suspension will compress near it's full travel, so that means the tire will touch the body? I wouldn't like that to happen on a track.

Is this problem causes by a non ideal offset? Or all 255s rub?

Fitting a 255 tire in the front is a compromise.

Everything depends on Caster, Camber, ride height, offset and the tire.

The M suspension has extra caster pushing the wheel forward in the wheel arch. If your camber plates allow or force you to have less caster, have more room for the tire.

Non-M;s actually have an advantage here with the wheel being much further back.

If you get the tire close to the strut (higher offset), it may run the frame rail on full lock, move it out a bit an in a turn it may run the inside front of the wheel liner.

Move it out to far or have the car to low, you going to rub the top edge.

A 245/40 Hoosier A7 is larger than a 255 Dunlop or RE71. More G's = more loading = more compression = more rubbing.

But it does make for a very fun car with much more neutral handling.

[TurboBimmer]

Thanks SunsOut for the detailed reply.
I think I would go toward the ' frame rubbing under full lock ' option because the full lock condition is not something we see on the track but in a parking lot, so safer.
But having a higher offset kills the look, so one set of wheels for the track with high offset, and a more agressive offset set for the street :-)

You say that the non-M have an advantage because of a lower caster. Could a M be set like a non-M just by changing the top plates and/or the CAB? I don't think the lower caster would make a big difference if it is compensated with more camber with top plates?

[jbrannon7]

Goal: I'm looking to find some information about using two sets of rear Roadstars (all around), for a track setup.

Just quoting the original post. Your goal is not good. Having 9" roadstars all around on the track is a very bad idea.

[cutthegordian]

Thanks for the replies here E./jbran/sunz/Turbo, persuading me to not do roadstar rears all around for a track setup. I like the SSR setup and 17x9.5" ET15 recommendations. Though the "look" might be killed swapping for a track setup, i think the roll bar brings it together. Wish they had HMS Rollbars still available.

@E. - Thanks for posting those pics. Looks great. Glad to see it's doable. Only concern is the weight of the wheels.

@Jbrann - do you have a picture of your 18x10 setup?

[jbrannon7]

Thanks for the replies here E./jbran/sunz/Turbo, persuading me to not do roadstar rears all around for a track setup. I like the SSR setup and 17x9.5" ET15 recommendations. Though the "look" might be killed swapping for a track setup, i think the roll bar brings it together. Wish they had HMS Rollbars still available.

@E. - Thanks for posting those pics. Looks great. Glad to see it's doable. Only concern is the weight of the wheels.

@Jbrann - do you have a picture of your 18x10 setup?

17x9 with 255/40 17 front and 18x10 285/30-18 rear. Another nice option for light wheels that are designed with the proper backspacing for our cars is Apex Wheels. Every now and then they have good group buys. If I wasn't unemployed I might get some.

[cutthegordian]

Great pictures, looks nice. That group buy option sounds interesting. So long as i can get silver wheels to match the estoril blue.

@Jbran - harddog rollbar correct?

[jbrannon7]

Yes hard dog bar, if you get one the harness bar is too high and makes installation difficult. But it does add rigidity to the body. Cowl shake was noticeably decreased after installation. As to the photos, we are fortunate that several photo enthusiast come to our events and make the photos available for free download without water marks.

Here is their latest group buy. It may still be open.

http://www.bimmerforums.com/forum/sh...highlight=apex

[cutthegordian]

To confirm, Hard dog bar doesn't fit with the hard top does it? Thats what my research says, unless you're version is smaller?

Put a small word in your Apex rim link to see if it was still happening.

Meanwhile, i found this nearby. Wish it was 17x9.

http://vancouver.craigslist.ca/nvn/wto/5434107366.html