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Discussion Starter · #1 ·
Hi guys

i need help calculating what offset i need so i can order my new wheels, im fitting 9inch wide wheels to my zs, before i get loads of comments about how it cant be done im getting my wheels arches reworked to fit the wheels.

What i need to know is how to calculate it so the wheel comes into the arch the same distance it does now but the extra width of the wheel goes outwards if that makes sense.

Is there a website that offers a way to calculate it? also what offset is a mark 1 or 2?
 

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If you have the stock wheels can you not just use a small piece of flat wood or metal and place it between either side of the inner rim then use a tape to measure the distance from the centre to the hub. A bit basic but at least it would tell you the inset of the stock setup to the mm?

Paul.
 

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I did work this out once.
I think my 8x17's are a 45mm offset, but I have a 3mm spacer on the rear, so ideal offset should be 42mm

For 9x17 you would need around 20mm offset.
(or in a perfect world, 19rear and 22 front!)

9x17 will not fit under the front arches without running 3degree negative camber, fitting under the rear is not a problem.

You will need to remove quite a bit of metal from under the arches and remove the lip on the plastic bodykit. simply rolling the arches is not enough.
 

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Discussion Starter · #4 ·
I did work this out once.
I think my 8x17's are a 45mm offset, but I have a 3mm spacer on the rear, so ideal offset should be 42mm

For 9x17 you would need around 20mm offset.
(or in a perfect world, 19rear and 22 front!)

9x17 will not fit under the front arches without running 3degree negative camber, fitting under the rear is not a problem.

You will need to remove quite a bit of metal from under the arches and remove the lip on the plastic bodykit. simply rolling the arches is not enough.
Hi mate cheers for that, ill check that out, ive already got 7.5 inch rims and have got 22mm spacers on the back with only minimal rubbing as ive rolled the arches and trimmed the plastic. im glad you think different offset front and rear as ive been thinking that too. ive got a specialist wheel manufacturer helping me out now so hopefully will get it sorted,

thanks for the suggestions guys, cant wait to get them sorted and on the car!
 

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Hi mate cheers for that, ill check that out, ive already got 7.5 inch rims and have got 22mm spacers on the back with only minimal rubbing as ive rolled the arches and trimmed the plastic.
what spring rates are you running and does the wider rear track create oversteer?
Where did you get the spacers and how did you go on with the bolts in the hub?

im glad you think different offset front and rear as ive been thinking that too.
reason for different offset was not for looks, rather it would be such a tight fit and the clearences between wheels and arms/uprights are down to just a mm or 2.
The front is the biggest nightmare and the only way to squeeze the wheel in is by putting a few degrees of negative camber on it, but when you get the offset sorted on the front, you'll find you need a 3mm spacer or greater offset on the rear or the wheel would rub the rear arm.

The other thing you may need to look out for is tyre roll, but to be fair, this will only really be an issue if your running slicks on a track (road tyres will not create that much force/grip) (my rear arms showed slight tyre rubbing marks after a trackday and the tyres clear by 5mm)

I had team dynamics wheels 8jx17, the prorace1.2 is the same style wheel as the touring cars use and look very good in gunmetal satin. (good on price at 95quid a wheel to)
Let me know if your going the TD route, I keep toying with the idea of 9j myself and 2 sets would probably be a bit cheaper as well.
 

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Discussion Starter · #6 ·
Hi jason
i havent noticed oversteer at all, in fact i used to get no understeer just over steer and now the car is completely neutral its great. I bought the spacers from eibach i think they are designed for racing not as a looks thing,
they look like this but arent the same i cant find the link of the ones i bought http://www.demon-tweeks.co.uk/Search.do?method=delegate&n=1292&p=158941&s=wheel+spacers

but at the moment ive only got the spacers on the back as they dont fit on the front properly. so it wasnt intentional to have different front and back just waiting to get my wheel arches reworked on the front and also just noticed the back fits a wider track so as the handling its really good now when theyre wider at the back hence my thinking of different offsets for the final wheels.

Im probably going to get 2 sets of wheels as i want them for my road/track mk11 and also for my mk1 full track car thats if i can use 9inch wheels in the racing i want to do. Im getting some copies done hopefully of original touring car wings which will help with fitting the wheels on the front. I'll let you know prices i get quoted on the wheels if youre interested in a set too.

what spring rates are you running and does the wider rear track create oversteer?
Where did you get the spacers and how did you go on with the bolts in the hub?



reason for different offset was not for looks, rather it would be such a tight fit and the clearences between wheels and arms/uprights are down to just a mm or 2.
The front is the biggest nightmare and the only way to squeeze the wheel in is by putting a few degrees of negative camber on it, but when you get the offset sorted on the front, you'll find you need a 3mm spacer or greater offset on the rear or the wheel would rub the rear arm.

The other thing you may need to look out for is tyre roll, but to be fair, this will only really be an issue if your running slicks on a track (road tyres will not create that much force/grip) (my rear arms showed slight tyre rubbing marks after a trackday and the tyres clear by 5mm)

I had team dynamics wheels 8jx17, the prorace1.2 is the same style wheel as the touring cars use and look very good in gunmetal satin. (good on price at 95quid a wheel to)
Let me know if your going the TD route, I keep toying with the idea of 9j myself and 2 sets would probably be a bit cheaper as well.
 

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Hi guys

i need help calculating what offset i need so i can order my new wheels, im fitting 9inch wide wheels to my zs, before i get loads of comments about how it cant be done im getting my wheels arches reworked to fit the wheels.

What i need to know is how to calculate it so the wheel comes into the arch the same distance it does now but the extra width of the wheel goes outwards if that makes sense.

Is there a website that offers a way to calculate it? also what offset is a mark 1 or 2?
I think a good site is www.willtheyfit.com buddy :)
 

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Hi guys

i need help calculating what offset i need so i can order my new wheels, im fitting 9inch wide wheels to my zs, before i get loads of comments about how it cant be done im getting my wheels arches reworked to fit the wheels.

What i need to know is how to calculate it so the wheel comes into the arch the same distance it does now but the extra width of the wheel goes outwards if that makes sense.

Is there a website that offers a way to calculate it? also what offset is a mark 1 or 2?
how did you get on with this?

I am probably going to order 9x17 pro race 1.2 (btcc wheel), min offset is 23 which should be about right.

Team Dynamics will reduce the price from £126 per wheel is a few sets are ordered, so if anyone else fancies this....
 

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Hi mate cheers for that, ill check that out, ive already got 7.5 inch rims and have got 22mm spacers on the back with only minimal rubbing as ive rolled the arches and trimmed the plastic. im glad you think different offset front and rear as ive been thinking that too. ive got a specialist wheel manufacturer helping me out now so hopefully will get it sorted,

thanks for the suggestions guys, cant wait to get them sorted and on the car!
Why 22 mm spacers on the rear...?

Rubbings a pain with the mk2 arches
 
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