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      12-30-2020, 11:56 AM   #45
Expert@ApexWheels
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Quote:
Originally Posted by B328iC View Post
I know this is an old post but haw does the switching to the 17's from 18's effect handling? Does the increased "foot print" of the wider tires help it or does it make it easier to break loose due to the less rigidly of the sidewall. How does it effect the ride? On the street does the extra tire sidewall add a little more protection to the rim? I have a stock setup and only street drive mine.
Dropping down to a smaller diameter wheel and tire will result in the following differences:

1. Wheel weight. Going from 18" to 17" wheels will reduce your rotating mass at each corner, which will make for a more "nimble" handling feel, as the car will feel more eager to turn in and change direction.

2. Increased sidewall. With a larger sidewall, you will have improved ride comfort and compliance, which is great for street driving. While this can slightly increase sidewall flex on the front tires, the additional flex with the rear tires can result in less wheel-spin from a dig. The additional sidewall size can help protect your wheels from road hazards, as well.

3. Tire cost. Smaller diameter tires will typically be less expensive in most cases.

4. Brake clearance. This is the main negative aspect when dropping down to a smaller diameter wheel. With certain brake kits, clearance could potentially be an issue, requiring a spacer to clear smaller 17" wheels. Larger BBK's may not even be able to fit under certain 17" wheels, requiring 18" or larger diameters to clear.

Hope this helps and if you have any other questions, please let me know!

-Geirsen
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      12-30-2020, 03:00 PM   #46
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Thanks. My brakes are the stock ones that come on the M suspension option. So far they are adequate for my driving so I don't see the need to change. Mt car does have the staggered set-up on it and would probably stay with that and try to increase the "foot print" of the car.
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      12-30-2020, 04:34 PM   #47
///A D O L F O
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Hello, B328iC.

My Z4 originally came with 18" BBS Style 107. The wheels are nice, but I wanted something smaller and more aggressive, so I decided to put some 17" wheels. I haven't driven it that much to really answer your question as accurately as possible, but I can tell you that the difference in weight between the stock BBS and Konig Hypergrams is dramatic! I assume that the weight reduction would result in faster acceleration, or less work to spin the wheels. (Note that I'm a cyclist and have a basic understanding or rotational mass, but I'm not a physicist either.) The ride does feel more comfy with the bigger tires, but my coilovers are on the stiffest dampening setting. There are a couple of threads on here that talk about switching to 17s, or a track setup. Check them out:

1. https://www.zpost.com/forums/showthr...=694514&page=2

2. https://www.zpost.com/forums/showthread.php?t=676629

These two were very helpful in determining the best 17" setup for my Z4.

Thanks!
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      02-06-2021, 09:29 AM   #48
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Quote:
Originally Posted by ///A D O L F O View Post
Hello, B328iC.

My Z4 originally came with 18" BBS Style 107. The wheels are nice, but I wanted something smaller and more aggressive, so I decided to put some 17" wheels. I haven't driven it that much to really answer your question as accurately as possible, but I can tell you that the difference in weight between the stock BBS and Konig Hypergrams is dramatic! I assume that the weight reduction would result in faster acceleration, or less work to spin the wheels. (Note that I'm a cyclist and have a basic understanding or rotational mass, but I'm not a physicist either.) The ride does feel more comfy with the bigger tires, but my coilovers are on the stiffest dampening setting. There are a couple of threads on here that talk about switching to 17s, or a track setup. Check them out:

1. https://www.zpost.com/forums/showthr...=694514&page=2

2. https://www.zpost.com/forums/showthread.php?t=676629

These two were very helpful in determining the best 17" setup for my Z4.

Thanks!
Hello, Adolfo!

Did you use camber plates? Are they necessary for this setup? Any rubbing issues on front?
Currently I have 245/35R18 by 18x8 ET 40 square. I want to go with 255/35R18 on 18x9 ET40 square.
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      02-06-2021, 11:58 AM   #49
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Quote:
Originally Posted by mex777 View Post
Hello, Adolfo!

Did you use camber plates? Are they necessary for this setup? Any rubbing issues on front?
Currently I have 245/35R18 by 18x8 ET 40 square. I want to go with 255/35R18 on 18x9 ET40 square.
Are you lowered? Give this a look, it's M specific but you can get an idea if you're non M as well.
https://support.apexraceparts.com/hc...-Fitment-Guide.

255 up front more than likely you'll rub and need camber plates. M has more aggressive caster than non M so rub points will slightly differ. On my prefacelift on eibach/koni combo with camber plates 255/35/18 apex ec7 18x9 et 31 rub slight a full lock
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      02-06-2021, 03:53 PM   #50
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Quote:
Originally Posted by Piper1 View Post
Quote:
Originally Posted by mex777 View Post
Hello, Adolfo!

Did you use camber plates? Are they necessary for this setup? Any rubbing issues on front?
Currently I have 245/35R18 by 18x8 ET 40 square. I want to go with 255/35R18 on 18x9 ET40 square.
Are you lowered? Give this a look, it's M specific but you can get an idea if you're non M as well.
https://support.apexraceparts.com/hc...-Fitment-Guide.

255 up front more than likely you'll rub and need camber plates. M has more aggressive caster than non M so rub points will slightly differ. On my prefacelift on eibach/koni combo with camber plates 255/35/18 apex ec7 18x9 et 31 rub slight a full lock
The car is on stock suspension. 245/35R18 18x8 ET40 square.
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