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What Offset? - The Complete Wheel Guide

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^^^^ Didn't work for me.

Stock size - 15x6 +40

 

1.    6 *25.4 = 152.4

2.    152.4 /2 = 76.2

3.    76.2 - 40 = 36.2

 

No wide fenders.

 

New wheel  -  18 x 8.5

1.    8.5 * 25.4 = 215.9

2.    215.9 /2 = 107.9

3.    107.9 - (71.7) = 36.2

 

How can you have a +72 offset rim ????

Am I doing it wrong or will this just mean the rim will have more backspacing than stock or what?  Maybe with an extra 40mm backspacing it will reduce the offset to acceptable +32.

You did the calculations correct and got an answer based on the measurements of the factory stock wheels.

 

Compared to factory stock wheels 18x8.5 +72 will have the following characteristics

The clearance from stut housing to the inside of the wheel will be 64mm LESS

The outside edge of the wheel will extend to THE SAME point as the stock wheel

 

In other words..the new wheels will sit inside the fender and have the same amount of fender clearance as your stock rims. But have less clearance on the inside of the wheel.

 

Offset is reduce by adding spacers not from backspacing.

Ultimately backspacing has more to do with the clearance of the suspension and brake components.

 

In your case your best bet would be going with 17x8.5 +8 or close to it.

(The clearance from stut housing to the inside of the wheel will be THE SAME

The outside edge of the wheel will EXTEND an extra 64mm)

 

If you want the wheel to be flush with the fender use the offset calculator to find an offset that will make the outside edge of the wheel extend at least 73mm.

My definition of flush with the fender is the same as "Streeter's. In this case 17x8.5-1 would be flush with the fender.

Edited by Rayne

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3.    76.2 - 40 = 36.2

There's your problem.

 

You're offset is +40 not -40. (3. 76.2 + 40 = 116.2)

 

Therefore...

 

3. 107.9 + 8.3 = 116.2

 

+8 As stated above.

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Based on SpecS15 wheel size and offset (17x9 +10)

For the fronts -10 would be recommended.

For the rears -27 would be recommended

 

Before an offset can be specified the "Backspace" of a rim needs to be known.

 

Formula to find backspace:

1.) Multiply "Stock" width by 25.4 to convert rim width into mm (9*25.4=228.6mm)

2.) Divide rim width by two for the centerline of the wheel (228.6mm/2=114.3mm)

3.) Subtract or add "Stock" offset for the amount of backspace. (114.3mm-10=104.3mm)

If stock offset is positive, subtract. If stock offset is negitive, add.

The backspace for SpecS15 wheels is 104.3mm

 

If adding wide fenders add the extra room.

20mm wide front fenders(104.3mm+20mm=124.3mm)

50mm wide rear fenders(104.3mm+50mm=154.3mm)

 

To find the correct offset for the new wheel:

Keep stock wheel backspace in mind when doing the calculations for the new wheel.

1.) Multiply width of new wheel by 25.4 to convert rim width into mm (10*25.4=254mm)

2.) Divide rim width by two for the centerline of the wheel (254mm/2=127mm)

3.) Subtract or add offset for the amount of backspace. (127mm+27mm=154mm)

If added offset will be negitive. If subtracted offset will be positive

 

Finally use the offset calculator to double check calculations.

(__x9 -10)

The clearance from stut housing to the inside of the wheel will be 20mm MORE

The outside edge of the wheel will EXTEND an extra 20mm

 

(__x10 -27)

The clearance from stut housing to the inside of the wheel will be 24mm MORE

The outside edge of the wheel will EXTEND an extra 50mm

 

Backspace is the amount of space on the inside of the wheel. (Mounting surface to the inside edge of rim)

hi guys...im getting a little confused here. can anyone confirm this cos im getting different answers. this seems the most correct however the offsets seem a little TOO negative?

 

17x9 front : 20mm wider fenders

17x10 rear : 50mm wider fenders

 

-10 for the front and

-27 for the rear just seems too much

?

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Does anyone know how much furthur than stock inwards a rim can go comfortably for a 180? (For 235/40/18 & 255/35/18 if it helps)

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hi guys...im getting a little confused here. can anyone confirm this cos im getting different answers. this seems the most correct however the offsets seem a little TOO negative?

 

17x9 front : 20mm wider fenders

17x10 rear : 50mm wider fenders

 

-10 for the front and

-27 for the rear just seems too much

?

For the front:

Based on SpecS15 wheels and stock S15 wheels

17x9 +10 the edge of the wheel extends an extra 67mm beyond the stock wheel.

On top of that you intend on adding an additional 20mm. With that in mind you will have a combined total of 87mm of extra space underneath the rear fenders

 

Unless SpecS15 is using the M-Sports S15 20mm wide front fenders you need to figure out what offset will take up the additional 20mm. Running a negitive offset or using large spacers are your only choices.

 

Using the offset calculator with S15 factory stock specifications and "SpecS15" recommendations

 

Stock Wheel: 17x6.5 +45

New Wheel: 17x9 10

The clearance from stut housing to the inside of the wheel will be 23mm MORE

The outside edge of the wheel will EXTEND an extra 67mm

 

Using the offset calculator with S15 factory stock specifications and specifications I mentioned:

Stock Wheel: 17x6.5 +45

New Wheel: 17x10 -10

The clearance from stut housing to the inside of the wheel will be 28mm MORE

The outside edge of the wheel will EXTEND an extra 87mm

 

For the rear:

Once again based on SpecS15 wheels and stock S15 wheels

17x9 +10 the edge of the wheel extends an extra 67mm beyond the stock wheel.

On top of that you intend on adding an additional 50mm. With that in mind you will have a combined total of 117mm of extra space underneath the rear fenders.

 

If you decide to run +5 offset with a ten inch wide wheel the outside edge of the wheel will be 33 mm shy of being flush with the fender. If you want to the wheel's edge to be flush with the fender you need to figure out what offset will take up the additional 50mm. Running a negitive offset or using massive spacers are your only choices.

 

Using the offset calculator with S15 factory stock specifications and "SpecS15" recommendations

 

Stock Wheel: 17x6.5 +45

New Wheel: 17x9 +10

The clearance from stut housing to the inside of the wheel will be 3mm MORE

The outside edge of the wheel will EXTEND an extra 67mm

 

Using the offset calculator with S15 factory stock specifications and specifications you mentioned:

 

Stock Wheel: 17x6.5 +45

New Wheel: 17x10 +5

The clearance from stut housing to the inside of the wheel will be 4mm LESS

The outside edge of the wheel will EXTEND an extra 84mm

 

Using the offset calculator with S15 factory stock specifications and specifications I mentioned:

Stock Wheel: 17x6.5 +45

New Wheel: 17x10 -27

The clearance from stut housing to the inside of the wheel will be 28mm MORE

The outside edge of the wheel will EXTEND an extra 116mm

 

Ultimately it is your decision on what offsets you run with your set up. The offsets I am recommending require stretched tires and negitive camber. Also the set up I like is similar to that of many drifters with a VIP styling twist. (EX. BN Sports Blue S13)

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Does anyone know how much furthur than stock inwards a rim can go comfortably for a 180? (For 235/40/18 & 255/35/18 if it helps)

I cannot say that I know. When you have the chance measure the distance between your tire's sidewall and the edge of the fender.

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I was meaning the other side, how far in towards the middle of the car can the rim/tyre go before rubbing. I'm not with my 180 for another 3 weeks. :(

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Yeah, mine stuck out beyond the standard guards with the +10 offset, which would be fine for use with 20mm pumped guards, although I'd probably go a +5. I wish I had some better pictures of the front of the car with the old wheels on it so I could show you exactly how much but unfortunately they're all side on.

 

I took some shots of the new wheels, these are 8.5" +30 front and 9.5" +35 rear. So far it's worked pretty well, I've been pulled over a few times and let go. The last set of wheels I was defected for twice in one week because of the increased track, hence the reason why I sold them.

post-4-1109630367.jpg

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ok...so spec s15, with 20mm fenders at the front, what would sit flush with 17x9.... +10 or +5 offset? (basically what im asking for is how much further out did the wheels stick out at the front with ur work meisters?) mind you: im runnin 1.5 degrees neg camber and prolly intend to keep that.

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BEN: im currently looking at a 17 x 8 with a +45 offset, how would these fit to a 180sx with pumped fiberglass guards and pumped rear guards...... all help would be muchly appreciated

 

Cheers ADRIAN B)

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Mine would have stuck out 15mm easily, that was with -2.5 degrees camber, so a +10 should sit flush with 20mm over fenders and -1.5 degrees camber.

 

They'de probably sit about the same as how my new wheels are now at the front, although I'd still want mine pumped out another 5mm, hence the reason why I'd probably go a +5 if I were you.

 

Adrian: I got no idea what wheels would fit. Firstly I'm not sure what offset is flush with the standard guards, then you'de need to know how much wider the over fenders would make the car.

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thanx alot specs15.....im going 17x10 for the rear, so thats 2.5cm more than ur rear right? meaning its about 1.25cm more to the outside edge correct?

 

what offset would YOU recommend with 50mm rear overfenders?

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HELP NEEDED........

 

am looking for some new mags for my 180sx.... now what i need help with is this a perfect setup....

 

front: 17 x 8.5 +35

rear: 17 x 9.5 +35

 

now will this fit with no worries and how much dish would this put on the mag....

 

And also if i wanted to go:

 

front: 18 x 8 (what offset for big dish)

rear: 18 x 9.5 (what offset for big dish)

 

All help would be muchly appreciated ADRIAN

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For a 50mm rear overfender running 10" wheels I'd probably recommend a -12.

 

Adrian. If the 180 is anything like the S15, those wheels should be fine for the rear, but I'd probably go with a +25/+30 for the front.

 

With the dish its impossible to say "how much" purely based on an offset because each manufacturer and model is different, but the more negative the offset the more dish is possible. Like for a -12 offset wheel you'de probably be looking at around 100mm+ of dish depending on the manufacturer/model. A +35 offset you wouldn't really expect to have much dish at all, maybe 40 or 50mm at best.

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So a 18x9.5 on the rear +35 should fit ok on a 180?

And 18 x 8 +25/30 ok for the front?

 

I want this setup as well. Maybe 18x8.5 on front but don't want to use flares, just rolling/lipping if needed.

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So a 18x9.5 on the rear +35 should fit ok on a 180?

And 18 x 8 +25/30 ok for the front?

 

I want this setup as well. Maybe 18x8.5 on front but don't want to use flares, just rolling/lipping if needed.

With stock fenders...18x9.5 +35 on the rear would fit without having to do any modifications to the fenders.

The clearance from stut housing to the inside of the wheel will be 39mm LESS

The outside edge of the wheel will EXTEND an extra 49mm

 

in the front either offsets you mentioned will fit.

For an 18x8.5 wheel +24 or lower would work for stock fenders.

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NEED help with offset.......

 

im looking at having ROH make me some custom mags for my 180sx, however i need to give them sizes and offsets....

 

i wana run a 18 x 9 for the front and 18 x 9.5 for the rear, however what offset would be the best to get the most dish out of them.....

 

all help is muchly appreciated..... ADRIAN B)

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Hehe, I just got a reply for Work Wheels NZ about what offset I should use for some 18x8.5 and 18x9.5s CR Kai's and they told me I'd have to buy them through them before they would tell me!!! I'm going to see what price they can get them for before I be too rude. :lol:

If you guys are pretty certain that a +25 and +35 will be cool then I don't really need their help but they did say that they would fit an s13 easily with the right offset and 235/40/18 and 255/35/18s would be the go for tyres. 255s on the back would look tuff as and have shit loads of grip. They also said 18x7.5 and 18x8.5 would be too sunken.

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HEy guys....all i see is a alot of numbers and confusing sheite..dont know if these figures have been worked out...but im keen on getting some big dishies on my 180 and the specs are:

 

18 x 10.5 (-10) and 18 x 11.5 (-10)

 

to caiter for it i have a widebody..typical 25mm's up front/30s in the rear.

saying that i still want em to stick out a tad (20mm or so) and then work from there camber + more hacking at guards..

 

so my question is to all you offset math gurus...anyone know roughly or near abouts how far these mofos will actually stick out? and will my brakes/struts be fine, and not knocking the against sheite?

 

they wont see the track untill ive got my new engi setup in as the ol ca couldnt handle a few rotations of these babies in the rear.

 

please somebody work out these calculations for my specs!

thanks heaps.

 

Jimmy

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NEED help with offset.......

 

im looking at having ROH make me some custom mags for my 180sx, however i need to give them sizes and offsets....

 

i wana run a 18 x 9 for the front and 18 x 9.5 for the rear, however what offset would be the best to get the most dish out of them.....

 

all help is muchly appreciated..... ADRIAN B)

dude, your crazy buying ROH wheels. don't get roh wheels. they are shit and shit made. i know cause i used to work for them- and plus they are aussie wheels. ewwww.

 

anyways, you know what rims i got and you know what car they were on. so here's the specs:

 

18x8.5JJ +19 SB-5H X 114.3

18x10JJ +5 SB-5H X 114.3

 

on the 180s:

front needed 25mm spacers with fibreglass fenders, but sits dead flush with stock guards. rear were flared, without having to sort overfenders. ran slightly -ve camber with some 245s.

 

same goes for silvia.

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tN^: unfortunatley the only jap mags ive liked are either way over priced, or i simply dont like them....... so i personally believe that the best option is custom ROH, which make em to suit me, size, colour, offset etc etc.....

 

ADRIAN B)

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also i dont really wana run coilovers, so unfortunately i wont be really able to adjust the camber.......

 

So if i was to run a 18 x 8.5, will these fit comfortably without coilovers..... also same goes for the rears 18 x 9.5....

 

Cheers ADRIAN :D

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HEy guys....all i see is a alot of numbers and confusing sheite..dont know if these figures have been worked out...but im keen on getting some big dishies on my 180 and the specs are:

 

18 x 10.5 (-10) and 18 x 11.5 (-10)

 

to caiter for it i have a widebody..typical 25mm's up front/30s in the rear.

saying that i still want em to stick out a tad (20mm or so) and then work from there camber + more hacking at guards..

 

so my question is to all you offset math gurus...anyone know roughly or near abouts how far these mofos will actually stick out? and will my brakes/struts be fine, and not knocking the against sheite?

 

they wont see the track untill ive got my new engi setup in as the ol ca couldnt handle a few rotations of these babies in the rear.

 

please somebody work out these calculations for my specs!

thanks heaps.

 

Jimmy

Front:

If your idea of flush is similar to that of an 18x9 +10 wheel on a S13 you will want to a +4 offset with the 10.5 inch wide rims.

 

The clearance from stut housing to the inside of the wheel will be 13mm LESS

The outside edge of the wheel will EXTEND an extra 25mm

 

If your idea of flush is similar to that of an 18x9 +5 wheel on a S13 you will want to a -1 offset with the 10.5 inch wide rims.

 

The clearance from stut housing to the inside of the wheel will be 13mm LESS

The outside edge of the wheel will EXTEND an extra 25mm

 

Rear:

If your ideal flush is similar to that of an 18x9 +10 wheel on a S13 you will want to a +12 offset with the 11.5 inch wide rims.

 

The clearance from stut housing to the inside of the wheel will be 34mm LESS

The outside edge of the wheel will EXTEND an extra 30mm

 

If your ideal flush is similar to that of an 18x9 +5 wheel on a S13 you will want to a +7 offset with the 11.5 inch wide rims.

 

The clearance from stut housing to the inside of the wheel will be 34mm LESS

The outside edge of the wheel will EXTEND an extra 30mm

 

Keep in mind all of the above information will include the use of stretched tires and negitive camber. Depending on what you concider flush will determine what size tire you will need to run as well. (Example: "Streeter" runs 17x9 +5 with 215/45/17 on the rear of his S13)

 

As I have posted once before...brake clearance depends on spoke design not offset.

 

The math involved with figuring out offsets is basic stuff. Reread the posts in this thread and you will figure it out as well.

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For 18x7.5 and 18x8.5 on a 180 I have been told now by Works, C-Red, and WheelsWorld dude that +35 +37 is the way to go on stock guards.

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For 18x7.5 and 18x8.5 on a 180 I have been told now by Works, C-Red, and WheelsWorld dude that +35 +37 is the way to go on stock guards.

If you want to run those offsets that is your desicion. All of the information provided in this thread is here to help you decide, on your own, what offset you want to run depending on your particular style.

 

With the offsets recommended to you by a sales person you are looking at:

Front:

18x7.5 +35

The clearance from stut housing to the inside of the wheel will be 14mm LESS

The outside edge of the wheel will EXTEND an extra 24mm

 

Rear:

18x8.5 +37

The clearance from stut housing to the inside of the wheel will be 29mm LESS

The outside edge of the wheel will EXTEND an extra 35mm

 

Since you intend on dropping your car you may have problems with the tires rubbing against something. If and when that happens you may have to run smaller tires for extra clearance.

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So you think the backs might rub on the inside? I will be only dropping it to legal limit 100mm.

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So you think the backs might rub on the inside? I will be only dropping it to legal limit 100mm.

Depending on what size tire you run, the rears might. If you do experience rubbing be open to using spacers, fender modification, and/or smaller tires.

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Yeah, we'll see how I go, have 255s on the rear so it'll be tight but the 3 guys who told me the offset weren't saleman and they had done lots of silvia's before, a few other people told me different offsets on here but I just had to go with the most accepted specs. Unfortunately I'm 1500kms away from my car so I can't check what I think with my own eyes, just gotta hope its right. I don't mind a bit of rolling if it has to be done, could always swap the 255s for 245s but don't like the use of spacers

.

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