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Wheel offsets for dummies

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Due to the number of threads recently about people asking about wheel offsets and fitments, and not being able to understand them, I have made this idiots guide.

 

For all you people who are about to post up on this thread giving all this indepth details about it and explaining where I have went wrong - THIS IS AN IDIOTS GUIDE. Short and to the point just to help people get their heads around it initially, before they head off and do more reading around the forum.

 

 

PCD:

Pitch Circle Diameter is the diameter of a circle drawn through the centre of your wheels bolt holes.

Zeds are a 5 stud, with a PCD of 114.3

 

PCD-Explained2.png

 

Offset:

 

Effectively the offset is also the distance from the centre-line of the wheel to the hub face.

 

Therefore :

If you put a wheel on the same hub with a bigger offset, the wheel will sit further inside the wheel arch because the wheels bolting face will have to move further in to meet the hub.

 

Alternatively if it has a smaller offset it will sit further out from the wheel arch.

 

Zero Offset - The plane of the hub mounting surface is even with the centerline of the wheel.

Positive Offset - The plane of the hub mounting surface is shifted from the centerline toward the front or outside of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

Negative Offset - The plane of the hub mounting surface is toward the back or brake side of the wheel's centerline.

 

WheelOffset5gif-1.jpg

 

Zed offsets depend on how agressive a stance you want.

The OEM Rays are 8j wide, with an offset of +30.

If keeping the OEM Rays, members often fit 10mm spacers to push out the rims essentially creating an offset of +20.

 

When you are looking to buy new alloys for your car, the offset is important because you qill require your new wheels to clear the brake calipers. And for looks wise you want them to nicely fll the arches, and not to be lost inside them somewhere.

 

Here is a link to a wheel offset calculator (this link takes you to an external site that has no affiliation with 350z-uk)

http://www.1010tires.com/wheeloffsetcalculator.asp

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Good info, but perhaps a link to an offset calculator might be a good shout? :thumbs:

 

Done :thumbs:

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Zed offsets depend on how agressive a stance you want.

The OEM Rays are 8j wide, with an offset of +30.

If keeping the OEM Rays, members often fit 10mm spacers to push out the rims essentially creating an offset of +20.

 

Firstly, thanks for the guide, its certainly something I never understood before!

 

One question though, if a POSITIVE offset is closer to the outside of the wheel, how could adding a spacer reduce the offset? Assuming the positive offset is measured between the centre line and the outside, if it was already 30, then adding a spacer would take it further from the center and increase it???

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You have to imagine that the spacer is attached to the inside of the wheels hub face, not to the car itself.

That mean its makes the positive offset smaller as 30 (wheel original) - 10 (spacer) = 20 :thumbs:

 

I've bastardised one of the diagrams above to try and explain better:

 

offsetwithspacer.png

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If anyone knows , you could maybe add in what offset is required to clear the Brembo brakes and also what Offset you should aim for when buying new wheels - Could even add a sort of to line up with arches - Get ETXX then people could work out what to go for either side of that depending if they wanted it further out or in , Highest and Lowest ET that will fit the cars ect.

 

I also noticed you mention 10mm spacers but it was my understanding 20 Front/25 Rear were what people were doing .. ?

 

hope that contributes something :thumbs:

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Clearing Brembos will also depend on the spoke design aswell as offset.

 

IMO to get a flush look on a Z, you need an offset of around 12-15 but it will look crap if its not lowered aswell. If your not planning on lowering then ET20-25 is ideal

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Offset is also effected by wider wheels, the wider they are the higher an offset you will need to keep things flush compared to a skinnier wheel.

 

As Ian says though, in typical Zed width wheels, somewhere around an ET20 is about right.

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So what is the widest, flushest, with 0 offset that I can get (clearing the calipers?)

 

As stated above, depends on the design of the wheels. As well as the fact that an 8J ET0 is 5 inches narrower than a 13J ET0. The "poke" from the mounting face is what you are interested in, not the offset as that is relative to wheel width. :bang:

 

Lexx has done a damn good job on this thread, but the underlying point is that if you are going for the very best/closest fitment of wheels there is no way to know 100% if something will fit without trying it. Different spoke designs, backspacing, tyre choice, tyre size, camber, ride height and suspension specs all affect wheel fitment and thats before you start getting onto arch modifications.

 

One thing I will say is that £150/200 odd will get someone who knows what he is doing to come and roll your arches for you so if you do buy something and it rubs a little its easy to sort out. If you are serious about getting wheels that fit as nicely as possible, for me its a given to get the arches rolled anyway. :)

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So what is the widest, flushest, with 0 offset that I can get (clearing the calipers?)

 

As stated above, depends on the design of the wheels. As well as the fact that an 8J ET0 is 5 inches narrower than a 13J ET0. The "poke" from the mounting face is what you are interested in, not the offset as that is relative to wheel width. :bang:

 

Lexx has done a damn good job on this thread, but the underlying point is that if you are going for the very best/closest fitment of wheels there is no way to know 100% if something will fit without trying it. Different spoke designs, backspacing, tyre choice, tyre size, camber, ride height and suspension specs all affect wheel fitment and thats before you start getting onto arch modifications.

 

One thing I will say is that £150/200 odd will get someone who knows what he is doing to come and roll your arches for you so if you do buy something and it rubs a little its easy to sort out. If you are serious about getting wheels that fit as nicely as possible, for me its a given to get the arches rolled anyway. :)

What does the J stand for in the rim width? tried a google but didnt find anything use full really. What I was asking is a question to someone that's actually tried to fit the widest rim possible *thus fitting the widest rubber on it... and what they used. I've been looking at a set of wheels, their site is pretty good and it shows that if you got non brembo Z you can run ET22 instead of forcing it to ET12 when having brembo's on, thus makes me believe that when you look for these things then try and keep the Inner clearance pretty much the same for fronts (seems you go further in with rear due to caliper size I'm guessing). So to answer my own question if you don't want to role the archers the perfect rim width with ofset for a "Rota" type wheel is 18x10.5ET22 rear and 9.5ET12 front. :dance:... which you'd be able to stick a 295mm tyre on? :blush:

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J is to do with the bead of the rim, handily Ive just found this:

 

JJ = 18.0mm high x 13.0mm wide, with a 13.0mm radius

J = 17.5mm high x 13.0mm wide, with a 9.0mm radius :thumbs:

 

Id say 12J ET20 at standard ride height is the widest you could fit and have been told this works too, drop Rarerims a line and see what they say though as they have sold quite a few wheels in this size recently ;)

10.5 ET22 will fit easily, I used to run 10 ET15 with no issues at all. :)

 

Oh, BTW, despite all of whats been posted aove you still got your offsets wrong - ET12 will have 10mm less inner clearance than ET22 ;):p

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I always had trouble getting my head round this and therefore had to seek advice from the forum (thanks Stew) and Dan at Rare Rims when I bought my new wheels just before Christmas, I guess that makes me an idiot :p;) Thanks for taking the time to and trouble to do this Lexx, although it's too late for me it was like a bright light entering my darkness :wacko::surrender: and this had made it a lot clearer for me (does that make me a retrospective idiot? :) )

 

Thanks again :thumbs:

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I always had trouble getting my head round this and therefore had to seek advice from the forum (thanks Stew) and Dan at Rare Rims when I bought my new wheels just before Christmas, I guess that makes me an idiot :p;) Thanks for taking the time to and trouble to do this Lexx, although it's too late for me it was like a bright light entering my darkness :wacko::surrender: and this had made it a lot clearer for me (does that make me a retrospective idiot? :) )

 

Thanks again :thumbs:

 

No probs :thumbs:

I was going to refer a few people to your thread about offsets, but then realised it had got way too complicated and needed some serious reading to get out the information needed.

Hence this thread.

 

So long as it proves useful to come people, then that makes me happy :thumbs:

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Due to the number of threads recently about people asking about wheel offsets and fitments, and not being able to understand them, I have made this idiots guide.

 

For all you people who are about to post up on this thread giving all this indepth details about it and explaining where I have went wrong - THIS IS AN IDIOTS GUIDE. Short and to the point just to help people get their heads around it initially, before they head off and do more reading around the forum.

 

 

PCD:

Pitch Circle Diameter is the diameter of a circle drawn through the centre of your wheels bolt holes.

Zeds are a 5 stud, with a PCD of 114.3

 

PCD-Explained2.png

 

Offset:

 

Effectively the offset is also the distance from the centre-line of the wheel to the hub face.

 

Therefore :

If you put a wheel on the same hub with a bigger offset, the wheel will sit further inside the wheel arch because the wheels bolting face will have to move further in to meet the hub.

 

Alternatively if it has a smaller offset it will sit further out from the wheel arch.

 

Zero Offset - The plane of the hub mounting surface is even with the centerline of the wheel.

Positive Offset - The plane of the hub mounting surface is shifted from the centerline toward the front or outside of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

Negative Offset - The plane of the hub mounting surface is toward the back or brake side of the wheel's centerline.

 

WheelOffset5gif-1.jpg

 

Zed offsets depend on how agressive a stance you want.

The OEM Rays are 8j wide, with an offset of +30.

If keeping the OEM Rays, members often fit 10mm spacers to push out the rims essentially creating an offset of +20.

 

When you are looking to buy new alloys for your car, the offset is important because you qill require your new wheels to clear the brake calipers. And for looks wise you want them to nicely fll the arches, and not to be lost inside them somewhere.

 

Here is a link to a wheel offset calculator (this link takes you to an external site that has no affiliation with 350z-uk)

http://www.1010tires...tcalculator.asp

 

Maybe this will help u too

 

http://www.rimsntires.com/specspro.jsp

 

 

Michael

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I occasionally find myself perusing wheels, but quickly get bored as I have zero comprehension as to what will fit and keep the Zed as close to OEM set up (aggro free) as possible. This guide is really helpful, thanks :thumbs:

 

To take me one step further (and see if I actually do understand) could someone check my maths and deductions below make sense please?

 

If the 350z Rays Wheels (5 stud, with a PCD of 114.3) and tyres are the following:

 

Front - Size: 18 x 8.0 - Offset: + 30 mm - Tyre: 225/45/18

Rear - Size: 18 x 8.5 - Offset: + 33 mm - Tyre: 245/45/18

 

A broadly agreeable "Good Looking" spacer combo for the RAYS is: Front 20mm - Rear 25mm

 

So by my fag packet maths, the aftermarket 18" wheel and tyre combo which MOST CLOSELY matches OEM spec, but fills the arches nicely works out at:

 

Front - Size: 18 x 8.0 - Offset: + 10 mm - Tyre: 225/45/18

Rear - Size: 18 x 8.5 - Offset: + 8 mm - Tyre: 245/45/18

 

 

Which makes the after market 19" wheel and tyre combo which MOST CLOSELY matches OEM spec, but fills the arches nicely:

 

Front - Size: 19 x 8.0 - Offset: + 10 mm - Tyre: 225/40/19

Rear - Size: 19 x 8.5 - Offset: + 8 mm - Tyre: 245/40/19

 

Yeah? Or am I confused and not factored in where the brembos fit or the arches or some other school boy error?

 

Thanks.

Edited by SuperStu

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What is the largest width wheel (front and back) one can run on the 350z without issues?

Rear arches rolled

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Depends on offset and how much camber you want to run, there is a sticky thread with loads of examples of what people are running.

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try using willtheyfit.com

 

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