Ideal wheel/tire size for Z4M stock suspension?

[intoflatlines]

What are the ideal sizes for wheels and tires for a Z4M with stock suspension/fenders (no spacers)?

I've read a few threads here and it sounds like the ideal wheel sizes for a stock suspension are: 9" ET30 in the front and 10" ET25 in the rear. Is that accurate? How much leeway is there for the offsets? Does 17" vs 18" diameter make a difference with the ideal width/offset?

On a side note, I've been looking at APEX wheels and came up with a few more questions. For the EC-7 18" wheels, the closest I can get are "Profile 2" ET31 front and "Profile 3" ET25 rear. Why the different profiles? Also it's not tight enough where a 1mm difference in front offset would cause issues, right? I also looked at ARC-8 17" options but the only 17x9 ET30 option is a "Concave" wheel, while the 17x10 ET25 wheel is not concave. Is this going to cause a mismatch in appearance if put together?

So for tires, I also did some reading on here and a lot of people mention the ideal tire width, meaning that while you CAN fit an X width tire on a Y width wheel, it will not be beneficial to handling at all. So, with 9/10 inch wheels, it seems like the ideal tread width is 255/285. Is this right? Would it even fit without fender rolling or crazy camber?

[David70]

This thread has some good information on Apex wheels. I went with 8.5 front and 9.5 rear to avoid spacers, changing camber, or any other issues. Personally wouldn't go with 17" wheels but this is just a choice based on how it looks.

http://www.zpost.com/forums/showthread.php?t=768791

[intoflatlines]

Thanks for the link. I read on another thread here where people said 9"/10" was fine for stock suspension without spacers...?

[drbvac]

IT works fine without the spacers and the correct offsets - may not look as good as with some spacers but no problem with rubbing in any event.


2 Front - 19x8.5 ET40 245x40 - 19"
2 Rear 19x10 ET25 275x35 - 19"

[intoflatlines]

OK so will this combo work?

FRONT: 18x8.5 +35 w/ 245/40/18 Bridgestone RE-11
REAR: 18x9.5 +22 w/ 275/35/18 Bridgestone RE-11

Front with +35 is 15mm closer to brakes/suspension and 5mm closer to fender. There is also an +20 option which would bring it out to 20mm further out but the same distance to brakes/suspension.

Rear is ET22 which is 30mm further out to the fender. There are also +33 and +45 options.

Which would look better and be more functional?

[v3.2mc]

8.5 et35 front and 9.5 et22 rear, with 245f and 275r, are the exact specs I am on with factory suspension. no rubbing. flush to the fender. the front spec still keeps a negative scrub radius.

[sadar]

I used 8.5 265 front and 9.5 285 on the Rears of my z4m , the car was super balanced .

[intoflatlines]

Originally Posted by v3.2mc

8.5 et35 front and 9.5 et22 rear, with 245f and 275r, are the exact specs I am on with factory suspension. no rubbing. flush to the fender. the front spec still keeps a negative scrub radius.

Do you have any pics of the setup?

Originally Posted by sadar

I used 8.5 265 front and 9.5 285 on the Rears of my z4m , the car was super balanced .

What were the offsets? No rubbing even during parking lot maneuvers?

[dubsesd]

I have the same specs but with 10" rears et 26 (equals the same). Zero rubbing

[Finnegan]

Here are pics of two common options along with specs.

[v3.2mc]

my pics thread...

http://www.zpost.com/forums/showthread.php?t=658931

[intoflatlines]

18x9 ET42, 18x10 ET25 should fit, right?

Stock is 18x8 ET42, 18x9 ET30

rimsntires.com tells me that the wheel fitment would be exactly the same as stock. Is that right? Not sure how that's possible with different width and offsets, the extra width has to go somewhere, right?

But then what about tires? Are the wheels here too far in to allow wider tires?

[DRedman45]

Yeah that's definitely not correct, but those specs do extend past the oem wheels, but they fit fine.

[mtrhed]

I am running Apex EC-7 18x9 ET42, 18x9.5 ET22, with 245/40, 275/35 MSS and have no issues. You may have a whisper of rub at full lock on the stock suspension with the 245's at front. I am now running more caster and have no rub at all.

[3002 tii]

Originally Posted by mtrhed

I am running Apex EC-7 18x9 ET42, 18x9.5 ET22, with 245/40, 275/35 MSS and have no issues. You may have a whisper of rub at full lock on the stock suspension with the 245's at front. I am now running more caster and have no rub at all.

Why does more caster avoid rub? I would think being closer to the bumper to the bumper would only make it worse.

[DRedman45]

Originally Posted by 3002 tii

Why does more caster avoid rub? I would think being closer to the bumper to the bumper would only make it worse.

Caster won't make the wheel any closer to the bumper...it's the angle of the of the steering knuckle and shock...so more caster is like moving the top of the shock closer to the firewall

[mtrhed]

I'm not exactly sure if the pivot point is changed or if it's the dynamic neg. camber change that more caster increases. All I know is that after the caster increase from the Vorschlag plates at full caster(+7.8*), no rub at all during Uturns and tight maneuvering. Which is the only time it rubbed a tiny bit before.

[Expert@ApexWheels]

A lot of great information in this thread, thank you for all the feedback so far in regards to our wheels.

For the EC-7 wheels, we have been told by some customers that they were able to use the 18x9" ET31 Profile 2 front with the 245/40/18 street tires, paired up with the 18x10" ET25 Profile 3 rear with the 275/35/18 street tires at stock ride height without rubbing, but the fronts are very flush and are right at the fender. However, a lowered car may require some fender rolling in the rear to avoid any fender rubbing. Those that are looking to use a 255/35/18 front tire would want to have at least -2.5 degrees of camber to properly clear the fenders.

The more conservative fitment would be to go with the 18x8.5" ET35 EC-7 or ET38 ARC-8 front wheel paired with the 18x9.5" ET22 rear wheel, used with the same 245/40/18 and 275/35/18 sized tires. The 235/40/18 and 265/35/18 tire combination also works with these wheel sizes, but most of our customers would like to get as wide of a tire on their car as possible. Those looking to run a bit of a wider front wheel would opt for the 18x9" ET42, which we usually recommend at least a 5mm spacer for adequate strut clearance, though it is not always required since it comes down to the specific tire make and model.

[intoflatlines]

Originally Posted by David@ApexRaceParts

A lot of great information in this thread, thank you for all the feedback so far in regards to our wheels.

For the EC-7 wheels, we have been told by some customers that they were able to use the 18x9" ET31 Profile 2 front with the 245/40/18 street tires, paired up with the 18x10" ET25 Profile 3 rear with the 275/35/18 street tires at stock ride height without rubbing, but the fronts are very flush and are right at the fender. However, a lowered car may require some fender rolling in the rear to avoid any fender rubbing. Those that are looking to use a 255/35/18 front tire would want to have at least -2.5 degrees of camber to properly clear the fenders.

The more conservative fitment would be to go with the 18x8.5" ET35 EC-7 or ET38 ARC-8 front wheel paired with the 18x9.5" ET22 rear wheel, used with the same 245/40/18 and 275/35/18 sized tires. The 235/40/18 and 265/35/18 tire combination also works with these wheel sizes, but most of our customers would like to get as wide of a tire on their car as possible. Those looking to run a bit of a wider front wheel would opt for the 18x9" ET42, which we usually recommend at least a 5mm spacer for adequate strut clearance, though it is not always required since it comes down to the specific tire make and model.

Thanks David. In this thread (http://www.zpost.com/forums/showthre...=748096&page=3) you indicated that 18x9 ET42 with 245/40 and 18x10 ET25 with 275/35 (BFG Rivals) should work with stock suspension, so I am going that route. I'm signed up for the group buy, 2 days left before I can order!