Custom built wheel spec question

N55xS54 · 08-05-2017, 09:20 PM

Since we do not have many options for 1 piece wheels I want to get some made. Going with Forgestar M14. 18x8.5 front 18x9.5 for the rear. My question is this..... what is the "BEST" offset for both front and rear? 225/40 front tires, 255/35 rears..... Car is lowered on Cobb springs (same as Eibach Sport).... I want to avoid running spacers and want the best fitment without any rubbing issues. I do not want to roll my fenders. Thanks

Here is the wheel! Not sure on color combo yet

Eyeman · 08-06-2017, 11:31 AM

I'd definitely go with et42 up front. Rear is more complex. With a 9.5inch wheel, you could go really high before you'd run into the inner fender, like et62. But for best looks was far as how they stick out vs the front, et48 or so should be about right. If you want to play it safer, you could go a tad higher. Also, I'd try to find out what rear et might effect how concave the wheel will appear.

swagon · 08-06-2017, 02:58 PM

FWIW, Apex wheels are 18x8.5 ET45 & 18x9.5 ET58 and that is a proven setup...

BBS USA have recently added RI-A wheels on their website, which were previously only available in Japan I think. On the Japan website, they have a 1er-specific setup - 18x8 ET45 & 18x9 ET50. They are forged one-piece monoblocks. Most likely not cheap but I don't know how much your custom Forgestars would cost. http://bbs-japan.co.jp/en/products/1135/ http://www.bbs-usa.com/race_wheels/w....cfm?wheel=116

John_01 · 08-08-2017, 07:18 AM

ET43 Front. ET53 Rear. That will allow you to easily run a chunky 255 with street alignment, or even 265s. There's no need for higher offsets.

07tundra · 10-16-2017, 09:31 PM

Quote:

Originally Posted by John_01

ET43 Front. ET53 Rear. That will allow you to easily run a chunky 255 with street alignment, or even 265s. There's no need for higher offsets.

What about 18x8.5 et35 and 18x9.5 et40 I don't want run negative camber but I will roll or shave the fenders if i have to

John_01 · 10-16-2017, 10:26 PM

Quote:

Originally Posted by 07tundra

What about 18x8.5 et35 and 18x9.5 et40 I don't want run negative camber but I will roll or shave the fenders if i have to

Probably you would be better off with ET45 to ET50 on the rear. It depends on the tire (A LOT). With proper wide sporty tires I suggest that around ET50 is what you ideally want for the rear fitment. Especially since you say you want to keep stock alignment.

Possibly you can make lower offsets work if you are into custom fitments, but unlikely to be as fully functional as having the correct offset that is intended for the car.

dbronnik · 10-19-2017, 01:02 PM

+1 for ET58 being perfect for the rear for a 9.5" wheel. Apex made this offset specifically for our cars, you can fit a 275 on there without any issues, no way you can do that with ET40 (I couldn't even fit a 255 without rubbing on my rolled/trimmed/slightly pulled rear fenders!)

07tundra · 10-23-2017, 08:07 PM

yeah but what about wheel gap that looks disgusting

John_01 · 10-23-2017, 10:47 PM

The stock wheels are only 8.5" wide. Going to a 9.5" rear wheel will help the appearance, even if the offset remains similar.

08-05-2017, 09:20 PM	#1
N55xS54 New Member 1 Rep 18 Posts Drives: 2013 135I Join Date: Mar 2017 Location: Huntington Beach, CA iTrader: (0)	Custom built wheel spec question Since we do not have many options for 1 piece wheels I want to get some made. Going with Forgestar M14. 18x8.5 front 18x9.5 for the rear. My question is this..... what is the "BEST" offset for both front and rear? 225/40 front tires, 255/35 rears..... Car is lowered on Cobb springs (same as Eibach Sport).... I want to avoid running spacers and want the best fitment without any rubbing issues. I do not want to roll my fenders. Thanks Here is the wheel! Not sure on color combo yet
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08-06-2017, 11:31 AM	#2
Eyeman Colonel 121 Rep 2,037 Posts Drives: 2008 135 blk, blk, step Join Date: Jan 2009 Location: Atlanta, GA iTrader: (0) Garage List 1994 Porsche 968 Cab [0.00] 2017 AMG GTS [0.00] 1994 Porsche 968 Coupe [0.00] 1977 Mercedes 450SE ... [0.00] 2008 135 [8.00]	I'd definitely go with et42 up front. Rear is more complex. With a 9.5inch wheel, you could go really high before you'd run into the inner fender, like et62. But for best looks was far as how they stick out vs the front, et48 or so should be about right. If you want to play it safer, you could go a tad higher. Also, I'd try to find out what rear et might effect how concave the wheel will appear. __________________ Injen, RR OCC, MadDad Whisper, donut spare, 19x8.5et43fr 19x9.5et45r Volk LE37's, rear fenders rolled/pulled, PSS4S 225/35fr 255/30r, KW V1's, AR coated catless dps, Cross strutbar, CF grills and license plate holder, iCarbon diffuser, ETS black anodized FMIC, M3 control arms, Quaife, ER chargepipe, ForgeDV's, Topspeed Custom Tune, V3sims, Braille, Andrey_GTA rear hub mod, Ebay Mstyle front bumper and performance style side skirts.
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08-06-2017, 02:58 PM	#3
swagon Major General 13518 Rep 8,163 Posts Drives: F80 6MT Join Date: Jun 2013 Location: . iTrader: (0)	FWIW, Apex wheels are 18x8.5 ET45 & 18x9.5 ET58 and that is a proven setup... BBS USA have recently added RI-A wheels on their website, which were previously only available in Japan I think. On the Japan website, they have a 1er-specific setup - 18x8 ET45 & 18x9 ET50. They are forged one-piece monoblocks. Most likely not cheap but I don't know how much your custom Forgestars would cost. http://bbs-japan.co.jp/en/products/1135/ http://www.bbs-usa.com/race_wheels/w....cfm?wheel=116 __________________
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08-08-2017, 07:18 AM	#4
John_01 Colonel 232 Rep 2,643 Posts Drives: E90 325i, E82 135i Join Date: Mar 2009 Location: Sydney, Australia iTrader: (0)	ET43 Front. ET53 Rear. That will allow you to easily run a chunky 255 with street alignment, or even 265s. There's no need for higher offsets.
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10-19-2017, 01:02 PM	#7
dbronnik Lieutenant 223 Rep 542 Posts Drives: N54 E88 Join Date: Mar 2012 Location: California iTrader: (4) Garage List 2011 BMW X5M [0.00] 1999 BMW Z3M Coupe [8.33] 2008 BMW 135i Conve ... [5.66] 2009 BMW M3 [0.00]	+1 for ET58 being perfect for the rear for a 9.5" wheel. Apex made this offset specifically for our cars, you can fit a 275 on there without any issues, no way you can do that with ET40 (I couldn't even fit a 255 without rubbing on my rolled/trimmed/slightly pulled rear fenders!) __________________ My E88 Build My Parts for Sale
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10-23-2017, 08:07 PM	#8
07tundra Lieutenant Colonel 119 Rep 1,525 Posts Drives: 8.1L Chevy 2500hd Join Date: Jan 2012 Location: New Mexico iTrader: (9)	yeah but what about wheel gap that looks disgusting __________________ 2008 335i FFTEC ST 6266,), Boostbox, VRSF 3.5 exhaust, mtech front and rear, KWVll, APEX 18x9.0, 18x12= 305/35/18 NTO1s, BMS OCC, Rb PVC, M3 tri-color stitched S-wheel,MT SWAPPED, M3 LSD diff 2008 135i mods coming soon!
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10-23-2017, 10:47 PM	#9
John_01 Colonel 232 Rep 2,643 Posts Drives: E90 325i, E82 135i Join Date: Mar 2009 Location: Sydney, Australia iTrader: (0)	The stock wheels are only 8.5" wide. Going to a 9.5" rear wheel will help the appearance, even if the offset remains similar.
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