GS - 4th Gen (2013-2020) Discussion about the 2013 and up GS models

Mid to deep concave?

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Old 01-15-20, 05:13 AM
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gdog5149
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Default Mid to deep concave?

Can a mid to deep concave look be obtained with an 8.5 to 9.5" wide wheel? Is this an offset / backspace parameter and what is that (negative I assume) number?
Thanks in advance!
G
Old 01-15-20, 06:25 AM
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bigblack06
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Originally Posted by gdog5149
Can a mid to deep concave look be obtained with an 8.5 to 9.5" wide wheel? Is this an offset / backspace parameter and what is that (negative I assume) number?
Thanks in advance!
G
Thats not the offset but if you go 9.5 with a 40+ offset if will look somewhat concave but will also depend on the wheel of choice.
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Old 01-15-20, 07:10 AM
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TarmacSL3
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Originally Posted by gdog5149
Can a mid to deep concave look be obtained with an 8.5 to 9.5" wide wheel? Is this an offset / backspace parameter and what is that (negative I assume) number?
Thanks in advance!
G
You can achieve a Mid Concave with a 9.5" wheel, but like others have mentioned it all depends on the wheel/face design. I am running a 8.5" +30 (Face 1) Front and 9.5" +42 (Face 2 Mid Concave) Rear. For a deep concave you might need to go 10-10.5"




Old 01-15-20, 12:37 PM
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gdog5149
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Originally Posted by TarmacSL3
You can achieve a Mid Concave with a 9.5" wheel, but like others have mentioned it all depends on the wheel/face design. I am running a 8.5" +30 (Face 1) Front and 9.5" +42 (Face 2 Mid Concave) Rear. For a deep concave you might need to go 10-10.5"



What part of FL is that?
G
Old 01-15-20, 01:16 PM
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mikesd1980
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I have 20x10.5 in the rear. I believe mines would be considered a mid concave. I think rear wheels is +45 offset

Old 01-15-20, 01:40 PM
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gdog5149
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Originally Posted by mikesd1980
I have 20x10.5 in the rear. I believe mines would be considered a mid concave. I think rear wheels is +45 offset
Nice, I have the Nebula as well. I have an AWD car so I am guessing 9 to 9.5 inches are a max width for my car. I am running 245/35/19's.
Thanks
G
Old 01-15-20, 07:03 PM
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mikesd1980
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Originally Posted by gdog5149
Nice, I have the Nebula as well. I have an AWD car so I am guessing 9 to 9.5 inches are a max width for my car. I am running 245/35/19's.
Thanks
G
FYI, mines is AWD as well.
Old 01-16-20, 12:34 PM
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gdog5149
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Originally Posted by TarmacSL3
You can achieve a Mid Concave with a 9.5" wheel, but like others have mentioned it all depends on the wheel/face design. I am running a 8.5" +30 (Face 1) Front and 9.5" +42 (Face 2 Mid Concave) Rear. For a deep concave you might need to go 10-10.5"



You would think some mfg would make an extreme concave wheel without it being extremely wide i.e. 10+ inches. I am being told that a 9.5 will not clear my front brakes so it looks like 9 inches might be my max. Almost no 19x9 rims out there...they all seem to jump to 9,5...ugh
G
Old 01-16-20, 01:13 PM
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TarmacSL3
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Originally Posted by gdog5149
You would think some mfg would make an extreme concave wheel without it being extremely wide i.e. 10+ inches. I am being told that a 9.5 will not clear my front brakes so it looks like 9 inches might be my max. Almost no 19x9 rims out there...they all seem to jump to 9,5...ugh
G
Dont think its possible to make a extreme concave without going wider..I guess you are looking to do a square setup..Have you looked at TSW wheels? I am running 20x10 +40 square setup on my sons car. I tried to fit these on the GS when I first got it but they would not clear the front brakes without a 10mm spacer and then it would look ridiculous as they would sit so far out. They do have them in 19x9 +30 and 19x9.5 +39. The 19x9 would have a mild concave.

Old 01-16-20, 01:42 PM
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gdog5149
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Originally Posted by TarmacSL3
Dont think its possible to make a extreme concave without going wider..I guess you are looking to do a square setup..Have you looked at TSW wheels? I am running 20x10 +40 square setup on my sons car. I tried to fit these on the GS when I first got it but they would not clear the front brakes without a 10mm spacer and then it would look ridiculous as they would sit so far out. They do have them in 19x9 +30 and 19x9.5 +39. The 19x9 would have a mild concave.
I guess I do not understand the logic here. If the hub was moved deeper in to the rim, the concave would also be more pronounced. Kind of like my truck rims with a deeper lip due to the negative offset. Seems like a 2 or 3 inch concave on a 9 inch wide rim would not be a huge challenge, but I am not a mechanical engineer either...lol
G
Old 01-16-20, 01:45 PM
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gdog5149
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This is what I am referring to,,,,just move the hub back to the x-y point.... I mean wtf right...lol
G
Old 01-17-20, 03:40 PM
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DuB
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It's hard to get a deep concave with our cars due to the relationship between the hub and the fenders. By the time you get down to the 20s in offset, let alone even talking the teens, the front lip of the wheel is starting to poke out from the fenders, which means you have to do a lot of work to get them to fit (roll/cut/pull fenders, negative camber). Forget about negative offset unless you're willing to run a lot of camber.
Old 01-18-20, 05:19 AM
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gdog5149
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Originally Posted by DuB
It's hard to get a deep concave with our cars due to the relationship between the hub and the fenders. By the time you get down to the 20s in offset, let alone even talking the teens, the front lip of the wheel is starting to poke out from the fenders, which means you have to do a lot of work to get them to fit (roll/cut/pull fenders, negative camber). Forget about negative offset unless you're willing to run a lot of camber.
Yea, it looks like I will have to curb my enthusiasm on the concave and do maybe a stepped lip wheel instead....... :-(
G
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