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S12 Technical Areas => Handling Tech => Topic started by: Arro on 01:17:41 AM / 06-Aug-09

Title: Wheel Offset
Post by: Arro on 01:17:41 AM / 06-Aug-09
A VERY common question on this forum is if a wheel will fit. The real concern isn't diameter, but OFFSET.

Offset is how we measure the center surface that mates with the hub.

(http://www.gtsparkplugs.com/images/WheelOffset5.gif)

Our wheels are a low positive offset. Most FWD wheels are a higher positive offset, and many oldschool RWD vehicles use a zero or even negative offset.

It's important to note that the stock wheels are +35. It's also important to know that in stock form, the stock wheels are sunk into the wheel well.

Generally a common size is 7" wide, zero offset. This usually fits nearly flush (maybe a milimeter or two over). With the rear suspension dropped some, the rear tires will easilly tuck in.

But another thing to note is that the fender lip on the front is not as far out as the fender lip on the rear. This is actually true of S13, S14, Z32, Z33, Z34, G35 sedan, and even 1G Z cars like the 240Z through the 280Z. What this means is that you can run wider wheels/tires in the rear and be flush.... what they call a "staggered" wheel set.

So how do you calculate the proper offset to get the best fitment?

Here is a handy calculator to do just that!

http://www.1010tires.com/WheelOffsetCalculator.asp (http://www.1010tires.com/WheelOffsetCalculator.asp)

You input the specs of your wheels as they are now. You then input the specs of the proposed wheels. It gives you the extra depth and outside measurements. Go and grab the ruler and eyeball the shocks on the inside, and the fender lip on the outside.


Title: Wheel Offset
Post by: brewster240 on 01:44:49 AM / 06-Aug-09
i think this goes hand in hand with this:

http://www.miata.net/garage/tirecalc.html (http://www.miata.net/garage/tirecalc.html)
Title: Wheel Offset
Post by: Arro on 01:46:21 AM / 06-Aug-09
Yeah, except that it doesn't show tire width vs. wheel to illustrate stretch vs. balloon... then again that fluctuates with brand and model of tires.
Title: Wheel Offset
Post by: brewster240 on 01:50:37 AM / 06-Aug-09
i just noticed you posted a calc in yours, i skipped over that somehow.

i guess delete mine if you want to clean this up.

wait, yours is an offset calc.

i guess thats a sign for me to go to sleep
Title: Wheel Offset
Post by: Maxpow on 02:28:07 AM / 06-Aug-09
I've got the best one hands down, been using it since I had the eclipse:

http://www.wheelsmaster.com/rt_specs.jsp (http://www.wheelsmaster.com/rt_specs.jsp)
Title: Re: Wheel Offset
Post by: Micro S12 on 11:44:40 AM / 28-Sep-10
I´m thinking of getting a set of steelrims widened.
But I dont know how wide and what offset they should be when they are done.
Can anyone help me with what offset and dimensions i should order?
And what is the widest you can squese in?
Width:
Offset:

Were thinking of getting stretched tires for them later.
Title: Re: Wheel Offset
Post by: Xano on 04:29:07 PM / 28-Sep-10
there are people running 9" wide in the back i believe. and 8" in the front fits ok.

i know that my 7" 0 offset wheels poke out a tiny bit on the front, and are a tiny bit sunken in on the back.

So use that as you will. 
Title: Re: Wheel Offset
Post by: Arro on 05:12:02 PM / 28-Sep-10
You can run 9" wide tires in the back if your offset is no lower than -10. To run like that, you're gonna have to run a mad stretch with like 205 width tires in order to clear the rear quarterpanel lip. So what's the point?

All you really get for going with a 9" low offset wheel in the rear is more expensive wheels to buy, and screwing with the offset. Unless you're gonna run fender flares, stick with 8" max width and zero offset (which is more common and less expensive).

If you want to run wider, just don't go "hellaflush", and keep the offset closer to zero. Then you also get the advantage of running with wider tires.

Also, your ride height determins the angle of the suspension and thus how the tires will fit when flush. Keep this in mind.
Title: Re: Wheel Offset
Post by: Maxpow on 06:28:33 PM / 28-Sep-10
Fender flares, -15(or more) offset, 315's in the back, 275's up front.


That would be hawt.
Title: Re: Wheel Offset
Post by: EightySix200SX on 10:10:54 AM / 01-Oct-10
Lol just wait you'll see
Title: Re: Wheel Offset
Post by: sam31183 on 01:06:26 PM / 01-Oct-10
i need to test fit all 4 of those steelies/slicks on the car....lol.
Title: Re: Wheel Offset
Post by: Arro on 11:44:06 PM / 01-Oct-10
Keep the discussion on the specifics of offset, any examples should be seperate threads.
Title: Re: Wheel Offset
Post by: iceageg on 02:51:58 PM / 12-Aug-11
As I troll through the archive of knowledge that is burried in these forums I noticed that there are a couple things worth mentioning here.

First, using wheels with an offset improper for your vehicle can greatly impact the life of your wheel bearings.  This is usually more of an issue in heavier cars and trucks, but still worth noting.  As light as S12s are they likely allow for quite a bit more wiggle room to deviate from this general rule.  The closer you can stay to the original configuration the less contribution your wheels will have on the bearing life.

Second, you noted above that FWD vehicles usually have a positive offset and many RWD use zero or negative offset.  Some of the more exotic AWD cars like Lamborghinis have used positive offset on the fronts and negatives on the rear of the same vehicle.
Title: Re: Wheel Offset
Post by: silverton on 04:12:38 PM / 12-Aug-11
Nissan just seems to like using positive offset wheels.  s12, z31, z32, wd21, etc etc.
Title: Re: Wheel Offset
Post by: nismo_200sx on 09:10:24 PM / 12-Aug-11
i want true 16x8 all the way around but i want a flush fit. no sunken in look and not too much plus offset. also no rubbing whatsoever. can you guys help?
i put 16x8 +12 cause if i have +0 it will hit the struts and stuff when im lowered wont it? i dont mind staggered but i just would prefer the same all the way around you know in case i flip them around when i put different tires on etc since i will be drifting.
i used the original comparison link arro had put up. i wouldnt mind a mild stretch so could i run 205's or run 195's on 8 inch wide? also would +12 offset have some sort of lip? i like lips.
Title: Re: Wheel Offset
Post by: silvia love on 09:21:10 PM / 12-Aug-11
an 8'' wide rim with a zero offset and 205/55r16's will rub like a mofo on our rears

8'' wide rim with +15 offset up front fits good with a little neg camber, stock camber rubs on 205/55, which should roughly fit the same as a 7'' wide rim with a zero offset and same height tires

rim width is as important as offset when going for a flush fitment. a 15*7 et 0 and a 15*8 et0 will fit differently, it would be like having a 15*7 et -15 or so to match the extra inch in width.... just had to throw that out there in case some are still confused
Title: Re: Wheel Offset
Post by: Arro on 01:38:58 AM / 13-Aug-11
I have 7" wide and zero offset with 195's and they don't clear without some negative camber... I have 205's on the same wheels in the rear, and when I tried those 205's in the front, there was no way the would clear the fenders even when I maxxed out my top camber plates negative.

basically an 8" wide rim with +15 is not going to fit with a 205 tire on the front. 195 with 2 degrees neg. or more, maybe.

But he wants more of a flush fit, not something that pokes until you tuck it in with camber. Chances are, he doesn't have camber plates at the top. So the reality is, he shouldn't be running an 8" wheel in the front at all, because there just aren't many 16x8 or even 15x8 wheel choices in an offset that would be the right fit that he wants... to run 8" and flush in the front, he needs something closer to our factory offset. Keep in mind or factory wheels are 6" wide, so add another inch outward with the same offset (to get an 8" wide wheel) and you have flushness.. only, it won't clear the strut tube.

What I'm getting at is an 8" wheel that's close to flush is just not a realistic option, 7" is a better bet for the front. This is also why IMO, if you are worried about traction, go staggered with 8" all around.

The exception to this would be super-stretched tires, massive negative camber, and probably some major fender pulling.
Title: Re: Wheel Offset
Post by: Athens on 04:18:01 AM / 13-Aug-11
Cut the fender and run ZG Flares off a 240Z. You'd probably be able to fit an 8" in the front with that, granted you have the optimal offset and tire size.
Title: Re: Wheel Offset
Post by: Deezus on 06:16:03 AM / 13-Aug-11
First, using wheels with an offset improper for your vehicle can greatly impact the life of your wheel bearings.

everything we do to cars is bad for them.
Title: Re: Wheel Offset
Post by: nismo_200sx on 06:20:27 PM / 13-Aug-11
I have 7" wide and zero offset with 195's and they don't clear without some negative camber... I have 205's on the same wheels in the rear, and when I tried those 205's in the front, there was no way the would clear the fenders even when I maxxed out my top camber plates negative.

basically an 8" wide rim with +15 is not going to fit with a 205 tire on the front. 195 with 2 degrees neg. or more, maybe.

But he wants more of a flush fit, not something that pokes until you tuck it in with camber. Chances are, he doesn't have camber plates at the top. So the reality is, he shouldn't be running an 8" wheel in the front at all, because there just aren't many 16x8 or even 15x8 wheel choices in an offset that would be the right fit that he wants... to run 8" and flush in the front, he needs something closer to our factory offset. Keep in mind or factory wheels are 6" wide, so add another inch outward with the same offset (to get an 8" wide wheel) and you have flushness.. only, it won't clear the strut tube.

What I'm getting at is an 8" wheel that's close to flush is just not a realistic option, 7" is a better bet for the front. This is also why IMO, if you are worried about traction, go staggered with 8" all around.

The exception to this would be super-stretched tires, massive negative camber, and probably some major fender pulling.
so a 16x7 +12 195 in the front work out good? no rubbing strut tubes, fenders, etc, and 16x8 +12 in the rear with 205 work the same way? complete fitment no rubbing dope looking.
Title: Re: Wheel Offset
Post by: silvia love on 08:07:55 PM / 13-Aug-11
tire stretching should only be on a 9'' or wider rim, stretching on a 7'' is pointless. 8'' maybe....stretching on narrow rims means super narrow tread, shit it would probably be less wide than factory haha and look like shit.


nismo_200sx
for the sizes u listed the tire width you want would be fine but the aspect ratio goes hand and hand with thread width. so 195/55 or 60 will rub but a 195/50 would be fine. same for the rear go 205/50.

my wheels on my car are 16x8 et15 i run a 15mm spacer in the rear. i rub slightly with 205/55's with a good fender roll. im dropping to a 205/45 to fix my rubbing.
Title: Re: Wheel Offset
Post by: Arro on 08:48:49 PM / 13-Aug-11
When I say "stretch", I mean anything narrower than a 205 on a 7" wheel, or a 215 in an 8" wheel. You're thinking super-stretch, fanboy-style. To me, anything less than square on a wheel is a stretch, and anything more than square is ballooned... I sold tires for awhile, that was the industry definition.

An 8" wheel with a 195 width tire is stretched. Not severely, and it's a safe stretch. But it's stretched.

If you're going to run 195 width tires on the front, I don't see why you would want to run an 8" wheel in the front... unless it's STRICTLY for looks. Because you won't be running a 205 on a 7" zero offset wheel ON THE FRONT, much less an 8" zero offset wheel. Notice I keep emphasizing FRONT, because you mentioned the rears twice now.

So in the front,  you have 8" wheels w/ 195's that rub. I run 7" wheels w/ 195's and I *don't* rub. Make sense?

Of course, since you mentioned the rears, I agree that 205 will fit w/ Erosion offset, regardless if it's a 7" or 8" wheel. Spacers? I had 1/4" slavers on either side of the rears and it barely rubbed when the suspension fully articulated upward... I suppose with super-stiff spring rates it wouldn't. Again, I'm also talking about an IRS car that allows you to tuck the shoulder of the tire under the quarterpanel lips. If you slot the subframe for some camber correction, those slavers would have to go... and SRA cars won't be able to do this at all (they will need different offsets entirely, not zero).



Post Merge: 01:30:40 PM / 14-Aug-11
Iceageg, I removed posts I felt digressed (including pics of irrellevant cars like S13's), just a head's up, but I agree with your sentiments.

What can remain in here is testimony from people who have tried things, done proper measure and math, and explain their statements clearly.
Title: Re: Wheel Offset
Post by: 88 200sx se on 10:11:18 PM / 20-Sep-11
I run Z33 17 in wheels on mine and it seems to flush on the outside of the fronts with 215's and just clear the back quarter with 225's. But mine is also not drop so I wouldn't know it the outcome for the front would be if it was to be drop.

Spec's: 17X7.5 +30 and 17X8 +33

Don't know if this would help out a little.
Title: Re: Wheel Offset
Post by: Arro on 10:37:20 PM / 20-Sep-11
Well considering that factory S12 wheels are I believe +38, you're losing 8mm on the front, which allows for more than enough to compensate for the extra width of the wheel. Same with the back. If anything, you should be a bit less than flush. You're right tho, a drop (especially true of the rear) will tilt them inward more as you lower it, which changes things.

Title: Re: Wheel Offset
Post by: Jeremy A on 01:04:12 AM / 21-Sep-11
Arro,  15x7 +10et,  or 15x8 +6et? 
Title: Re: Wheel Offset
Post by: Arro on 01:11:35 AM / 21-Sep-11
Um think about this, 15x7+10 is just a teeeeeensy tiny bit out past flush... so another inch wide, and another 4mm outward offset... means another 4mm plus a half inch (which is approx 10mm. Well, more like 12.7mm exactly)....

So basically, a 15x8 +6 will sit nearly 17mm further outward from where the 15x7 +10 does, which is already a milimeter or two out.

Also, remember that what fits one way for the front won't necessarily fit in the rear the same. Which is why sometimes we stagger widths and/or offsets.

What wheel style are you considering? That's as good a place to start as any, and worth starting a separate thread about. "This is the wheel style I want to go with, help with fitment" or something like that for the title. Go4it.
Title: Re: Wheel Offset
Post by: S12-AR on 04:47:22 AM / 02-Nov-11
Calculating the offset of a wheel
 
First, measure the overall width of the wheel (remember, just because a wheel is 18x7.5, does not mean that the OVERALL width is 7.5”. It means that the measurement between the outboard flange and the inboard flange is 7.5”). Next, divide that width of the wheel by two; this will give you the centerline of the wheel.
 
Overall width/2 = Centerline
 
After determining the centerline, measure from the hub-mounting surface of the hub to the edge of the inboard flange (if the wheel were laying flat on the ground – face up – your measurement would be from the ground to the hub-mounting surface). This is your back spacing.
 
Back spacing - Centerline = Offset
Title: Re: Wheel Offset
Post by: nismo_200sx on 12:07:39 AM / 03-Nov-11
Arro so in relation to my question what pokes out just a little bit in the front like a little bit i mean the width of my pinky finger.
the rims i want only come in these sizes
16 x 7   4 x 114.3   +25
16 x 7   4 x 114.3   +22
16 x 7   4 x 114.3   +20
16 x 7   4 x 114.3   +12
which one would be optimal for the front?

and for the rears in the same rims
16 x 8   4 x 114.3   +20
16 x 8   4 x 114.3   +4
16 x 8   4 x 114.3   +10
16 x 8   4 x 114.3   +15
which would be optimal in the rear?

Im gonna go with canuck motorsports drop springs and new struts so no intense suspension mods. just an all around ok drift car.
Title: Re: Wheel Offset
Post by: Jay on 01:10:53 AM / 03-Nov-11
Front +12
Rear  +10 or +4

Depends on IRS or SRA for that one.
Title: Re: Wheel Offset
Post by: Jeremy A on 01:29:46 AM / 03-Nov-11
Which if IRS?  Which if SRA?
Title: Re: Wheel Offset
Post by: Jay on 01:41:44 AM / 03-Nov-11
SRA +4, IRS +10

The SRA is more narrow than the IRS. Just look at my sig and SRA car.

15x7 +17 front. No poke perfectly flush
15x7 +17 rear. Probably needs to come out 40mm to be flush. It's sunk in there bad

You could do the +4 on an IRS car, but I see it poking out a little. Which would suit nismos desire
Title: Re: Wheel Offset
Post by: nismo_200sx on 12:47:37 PM / 03-Nov-11
so if i went +4 in the rear would i rub? im thinking in terms of not having to touch the fenders or  have them rub. im just not gonna do that.
Title: Re: Wheel Offset
Post by: Arro on 03:21:51 AM / 11-Nov-11
I have 7" offset zero wheels and they're about two fingers out from the lip, so I agree with Jay's assessment.

Also, the lower you go in the rear, the more the IRS will "tuck" in the top of the tires.... the wheel starts to tilt into negative camber and the top of the tire moves inward and has more clearance.

If you ever plan to use a camber correction kit, however, this will effectively remove that extra "tucked in" clearance from lowering. Well most of it, anyways.
Title: Re: Wheel Offset
Post by: dkdsilver on 01:06:50 AM / 08-Nov-12
could i get 16x8 zero in rear and 16 x8 +12 front?
Title: Re: Wheel Offset
Post by: Does it moo? on 04:45:33 AM / 18-May-13
http://www.willtheyfit.com/

Couldn't see this link posted here. Before I found it I was a monumental spazz regarding wheels, so it might help someone else too.
Title: Re: Wheel Offset
Post by: pakii-afa on 02:01:50 PM / 23-Feb-14
my s12 is not driving at the moment, but i need to move it from one location to another, its on blocks right now. my friend has a set of 17x7.5 +40 offest on 205/45s. i bought my car with stock 15x6 +35 on 205/65s so the new tires are shorter in height, but will they clear the inside since the new ones will sit an inch inward. would these work for a 10mile drive?
Title: Re: Wheel Offset
Post by: EternalSwap on 08:21:17 PM / 23-Feb-14
No, highly probable they will hit the strut.
Title: Re: Wheel Offset
Post by: pakii-afa on 01:39:56 AM / 24-Feb-14
thought that might be the issue, sorry for reviving a dead thread but i figured a sticky is better than new thread for a simple question, chats kind of dead recently too. i guess we will find out tomorrow, although i do have s13 coil overs on it so it may clear  :shifty:

on a side note i do remember i drove the car on 15x5.5+50 for a week, which are 15.4mm outward from the 17s i can put on it. so fingers crossed.
Title: Re: Wheel Offset
Post by: pakii-afa on 04:28:31 PM / 25-Feb-14
update : THEY FIT! :D exactly flush with the fender on the front, and the aprox 25mm norrower on the rear. inside wheel just fits on both front and rear, and i still have full lock on steering :)
Title: Re: Wheel Offset
Post by: aS12namedLetty on 01:05:05 PM / 06-Apr-15
i have an 86' with the canuck lowering springs, 280 strut sleeves in front and 92 5.0 shocks in back.
rim size is 15X8.25 +15 all around
tire size 195/60/15
when i had the stock sleeves in front there was some rubbing on big bumps, but with the 280 sleeves no rubbing ever