S2KSean

Starting to window shop for wheels and I just want to make sure I'm right on my math/terminology, so if someone could confirm that would be awesome.
1. Offset = Distance from wheel center line -> bolt mounting surface. (+ or - number)
2. Backspacing = Distance from inner wheel edge -> bolt mounting surface. (+ number only)
If those two terms are correct, then the numbers I have below should have the same backspacing, and would be equivalent to adding an extra 1.5" lip to the outside of a stock wheel. Correct?

Stock Front: 16" x 6.5" +55mm offset == (6.5 x 25.4)/2 + 55 = 137.55mm backspacing
New size: xx" x 8.0" +36mm offset == (8 x 25.4)/2 +36 = 137.60mm backspacing
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Stock Rear: 16" x 7.5" +65mm offset == (7.5 x 25.4)/2 + 65 = 160.25mm backspacing
New size: xx" x 9.0" +46mm offset == (9 x 25.4)/2 + 46 = 160.30mm backspacing

If all that is right, my only other question is how much more + backspacing can be had on front/rear before running into problems on the inside of the wheel/tire?

Manga_Spawn

Hmmm I am not familiar with the backspacing term but I do understand what you are talking about. I go by the offset and the width of the wheel. For instance a 17x7 wheel with a +45 offset is far less aggressive than a a 17x10 +45 offset wheel. Generally speaking the wider the wheel the higher the offset will need to be to clear the fenders. I know that volk makes 17x10 +70 wheels that fit the rear just fine (I think the front may rub on full lock). Frankly there is very few wheels out there that you will have to worry about the inside of the tire contacting. The issue most run into is the outside edge which is due to the offset.

sillyboybmxer

i think ccw wheels is the only company that uses the term "backspacing" since they gotta measure for custom sizes

S2KSean

So long as my terminology is right, my thoughts are as follows.
Offset would be wheel specific no pertaining to any vehcile, a 17x8 +45 would fit differently on my S2K than my Corrado (obviously).
While a vehicle's maximum backspacing allowance would let you run the widest rim possible.

Stock Front: 16" x 6.5" +55mm offset == (6.5 x 25.4)/2 + 55 = 137.55mm backspacing
New size: xx" x 8.0" +36mm offset == (8 x 25.4)/2 +36 = 137.60mm backspacing
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Stock Rear: 16" x 7.5" +65mm offset == (7.5 x 25.4)/2 + 65 = 160.25mm backspacing
New size: xx" x 9.0" +46mm offset == (9 x 25.4)/2 + 46 = 160.30mm backspacing

Volk: 17"x10" +70mm offset == (10 x 25.4)/2 +70 = 197.00mm backspacing, which is almost 1.5" extra rim on the INSIDE of the mounting surface.
Hypothetically, 17"x10" +100mm offset == (10 x 25.4)/2 +100 = 227.00mm backspacing, over 2.5inches extra INSIDE... eventually you're going to start hitting something and I'm just wondering at what point that is.

Manga_Spawn, what you're trying to say is that I'm probably not going to find a wheel that will have a barrel too deep for the S2K, and the only "worry" people have is the outer lip being too far out for fender?

AndrewLin

I believe if you call ccw you can ask them for the widest wheel they can make given a certain offset. I thought I remembered reading that somewhere on here

rapture12

You might want to dig in this site as well:
http://www.wheelsanything.com/

S2KSean

At a quick glance, nothing I'm looking for on there...

I'm at a toss up for the style I want to go with. "Race" or "VIP".
I've been looking at the Wedssport TC105N, Advan RSII, or Enkei NT03 for a race style look.
Or BBS LMs, CCW LM20s, or another wheel with a nice lip. Really hard to decide.

TardiS2K

From the research I've done into it, you have the correct impression of backspacing, and your calculations look correct. (I like the look of having a lot of inboard tire, so backspace room is of interest to me)

At what amount of backspace do you start having fitment issues clearing suspension parts, underbody, etc? I never found that out. But I have seen people report running somethingx11 +60/70s..

If I had the measuring equipment here at school, I would go down and find the most restricting location and find how much excess backspace there was between OEM wheel and the spot there really was. From there you could do the math. You could get a crude idea with a tape measure and a minute under the car. However, that might not account for suspension travel and how(if) it changes clearance in the rear.

In terms of 'race vs. vip', that's entirely preferential. If you can't decide, you might consider one of each. You could get a budget 'race' wheel and spend the real bucks on the 'vip' look for when you want it, or vice versa.

Hope I helped, let me know if you do end up finding out how much backspace the S can use..

S2KSean

I'll get the car up on the hoist at work soon and see what kind of measurement I can come up with.
Half of this equation is with my quick measurements at home in the driveway being...
You can add 1" to the 'exterior' of the front/rear rim to put the lip at the fender edge.

================================================== =================
Stock Front: 16" x 6.5" +55 == (6.5 x 25.4)/2 + 55 = 137.55mm backspacing
New Size: 16" x 7.5" +42 == 137.55 - ((7.5 x 25.4)/2) = Same backspacing with 1" Added to exterior lip.

Stock Rear: 16" x 7.5" +65 == (7.5 x 25.4)/2 + 65 = 160.25mm backspacing
New size: 16" x 8.5" +52 == 160.25 - ((8.5 x 25.4)/2) = Same backspacing with 1" Added to exterior lip.
Hypothetical: xx" x 11" +60 == (11 x 25.4)/2 + 60 = 199.7mm backspacing. An additional 39.45mm (1.55") 'inside' lip addition. (rear wheel)

11" - 7.5" = 3.5" wider total.
3.5" - 1.55" = 1.95" extra to the outside.
And my estimated 1" extra to fender edge leaves 1" of rim past the fender. All this is not factoring any sort of tire (stretched or not). So you'd need to run over fenders or have quite an extensive pull.

Assuming the 199.7mm backspacing does work, you'd hypothetically be able to run a == 199.7 - (10 x 25.4)/2) = xx" x 10" +73 and have the outer lip of the wheel at the stock fenders edge and only need a fender roll and minimal tire "stretch". (255 tire being square, estimate a 245 tire would work).

As I said before, If I don't have to pull/cut and weld fenders, I'd prefer not to. Also, I think 10" is as big as I'd like to run in the rear anyhow so if someone can confirm the previously mentioned xx" x 11" +60 on the rear I think I'd have the rear figured out.

================================================== =================

All that being said I'd probably be looking at running a 9" upfront.

9" - 6.5" = 2.5" wider total.
2.5" - estimated 1" to the outer = 1.5" remain to be added to backspacing.
137.55mm + 38.1mm = 175.65.... 175.66 - ((9 x 25.4)/2) = xx" x 9" +61
Can anyone confirm a xx" x 9" +61 on the front?

For the record this topic isn't for "Hella flush fitment yo!!"
I'm doing all this so that:
- I'm not just copying someones wheel setup, I'm learning.
- I couldn't really find any extensive info on this
- And more importantly so I can have the widest wheel possible, minimal body work (I just don't have the time with the other project), and so that I don't have to run excessive camber for the sole purpose of "fitting" my wheels. (I use the word "fitting" in the same sentence as "camber" very loosely).

TardiS2K

Sorry to bump an old thread but was there any more progress on whether or not this was correct? **x9 +61 seems like a pretty high offset to be at the fender's edge but I could easily be wrong and would like to confirm. 9" is what I'd like to fit up front at some point..

Thanks