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      09-19-2013, 03:37 PM   #1
drbvac
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Arc 8 wheels or 7's

IF I was to put APEX arc-8 wheels on that are

18 x 8.5 ofst 38 on the front
18 x 9.5 ofst 35 rear

WOULD - these tire size fit the wheels and the car "

Front 235/35 -18 or for that matter 245/35 - 18
rear 285/30 - 18

The combinations seem to be endless and I don't want spacers

Apex arc e-7s

front 18x8.5 35
rear 18 x 9-5 22

same tires


thanks as always to the real experts
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      09-19-2013, 04:28 PM   #2
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Far from an expert, but here's what I'd recommend:

Quote:
Originally Posted by drbvac View Post
IF I was to put APEX arc-8 wheels on that are

18 x 8.5 ofst 38 on the front
18 x 9.5 ofst 35 rear
Rear offset should be much lower, aka ET 22 if you don't want to run spacers.

Quote:
Originally Posted by drbvac View Post

Front 235/35 -18 or for that matter 245/35 - 18
rear 285/30 - 18
For 8.5/9.5 wheels I'd recommend 245/275. 285 will likely give you less grip and performance than 275.

Here's a thread with some beautiful 255/275 on arc-8.

http://www.zpost.com/forums/showthread.php?t=865009

I'd still recommend 245/275 just because it's about the largest you can fit with zero rubbing under any circumstance. And it's an ideal size for the rim width so you get the full contact patch. Finnegan in testing showed that having a smaller rim than the tire (even if the tire fits) gives you less performance than having the right rim width for the tire.
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      09-19-2013, 04:56 PM   #3
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You are correct -- the arc 8 with 22mm rear offset in 9.5 is the wheel but is not the 285 / 35 only .5 inches wider than the 275 - how would you get less grip - the 285 / 30 are too much of a change in circumference

So wheels are 18 x 8.5 -35 - and 18 x 9.5 -22 and then

Tires - 245x35 - 18 and 285 x 35 - 18 - Would they not fit OK ?

Numbers drive me nuts
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      09-19-2013, 06:28 PM   #4
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285 x 35 isn't going to fit without a lot of negative camber and probably some fender rolling. 245/275 is going to fit fairly easily front/rear, especially if you go with a rounded sidewall like the PSS. Square sidewalled tires, e.g. the Direzza II, will have better fitment in a 235/265 fitment on your choosen wheel size. A square shouldered 275 tire will need negative camber at the very least, and lots of it.

285 vs. 275 only gives a 4/10ths increase in section width, and you'd be stuffing it on to a wheel that has is the minimum width possible. Min width for a 285/35 tire is a 9.5".

Really needs a 10" or wider wheel, otherwise you're not going to use all that fat tire you paid for--basically you'll be using the center of the tire. (As Beta said, I've tested this using a pyrometer.) 10" wheel with a 285/35 tire isn't going to work without some serious work.
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      09-19-2013, 07:19 PM   #5
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Thanks Finnegan - if you ever need any advice on a root canal let me know,

ARC - 8 Front 18x8.5 - et 38 Tire 245/35 -18
Rear 18x9.5 - et 22 Tire 275/35 -18

Sound right this time - I noticed that the offsets for the Arc-8s have changed over the last while 0
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      09-19-2013, 10:06 PM   #6
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Quote:
Originally Posted by drbvac View Post
Thanks Finnegan - if you ever need any advice on a root canal let me know,

ARC - 8 Front 18x8.5 - et 38 Tire 245/35 -18
Rear 18x9.5 - et 22 Tire 275/35 -18

Sound right this time - I noticed that the offsets for the Arc-8s have changed over the last while 0
You want:

245/40
275/35

245/35 would be -4.7% smaller than stock, which is way too small (anything over 3% is said to cause issues with the DSC).

For reference:

245/40 -0.99% smaller than stock
275/35 -1.74% smaller than stock
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      09-20-2013, 06:59 AM   #7
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Quote:
Originally Posted by beta View Post
You want:

245/40
275/35

245/35 would be -4.7% smaller than stock, which is way too small (anything over 3% is said to cause issues with the DSC).

For reference:

245/40 -0.99% smaller than stock
275/35 -1.74% smaller than stock
SO I AM NOW GOING TO PRINT THIS OFF AND STICK IT TO THE CAR>:thump:

The 8-5" /18 ARC 8's have an offset of 38 but the ARC 7's have a 35 -- does it matter which one? I notice that it must be older stock but EAS has a set of them and the 8.5's are actually offset 45 which I think would keep them in more - which is preferable ?
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Last edited by drbvac; 09-20-2013 at 07:24 AM.. Reason: additional q
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      09-20-2013, 12:44 PM   #8
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Quote:
Originally Posted by drbvac View Post
SO I AM NOW GOING TO PRINT THIS OFF AND STICK IT TO THE CAR>:thump:

The 8-5" /18 ARC 8's have an offset of 38 but the ARC 7's have a 35 -- does it matter which one? I notice that it must be older stock but EAS has a set of them and the 8.5's are actually offset 45 which I think would keep them in more - which is preferable ?
Stock is 42. Since stock width is 8" and you're going to 8.5 you want anywhere from 35 - 40 roughly.

So you either want the Arc-8 et38 or the EC-7 et35.

If you got the 45's you'd have to get a 5-10mm spacer.
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      09-20-2013, 01:41 PM   #9
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You're the man !!
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      09-23-2013, 09:31 AM   #10
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Quote:
Originally Posted by beta View Post
Stock is 42. Since stock width is 8" and you're going to 8.5 you want anywhere from 35 - 40 roughly.

So you either want the Arc-8 et38 or the EC-7 et35.

If you got the 45's you'd have to get a 5-10mm spacer.
I think your post is clear but just to confirm... 8.5" with ET35 on the front would be OK on the front?
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      09-23-2013, 01:19 PM   #11
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Quote:
Originally Posted by intoflatlines View Post
I think your post is clear but just to confirm... 8.5" with ET35 on the front would be OK on the front?
Yes. And if you ever get coilovers (or lower the car) you'll push your camber out to somewhere around -2 approximately and it will be perfect as you'll get your scrub radius almost back to stock.
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      09-23-2013, 01:58 PM   #12
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I was on the fence about which of these two sets of wheels to get, and this weekend at the track there was a 1M with the Arc-8s and an E90 with the EC-7s. I think it's going to be Arc-8s for me!
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      09-23-2013, 02:55 PM   #13
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I think I will as well - have to wait till my Boss (She who must be obeyed ) isn't handy
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