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Davezj
28-01-2008, 12:04 AM
Hi All,

i have seen the diagrams for where the offset is measured from and to.

but this doesn't help if you don't kow what offset wheels you have.

how do you measure it. is it like this:
If you have no tyre on the wheel you can measure the center point between the outer rims but then you have to transpose this measurement to the inside of the wheel. then with a straight edge, extend the hub face of the wheel and measure back to the cetre line you have marked on the inside of the wheel.

but how do you do it with the tyre fitted.

see this thread for offset calculations.
http://www.clubvr4.com/forum/showthread.php?t=1484&highlight=wheel+spacers

the wheels i have come in 3 offset's (+35, 42, 52). see link below.

http://www.upgrademotoring.com/wheels/ss7.htm

can i make an assumption that the +35 and +52 would not fit under a vr4 arch anyway. as the wheels i have only just clear the outside edge of the arch, when you look down on it from above the front wing.

I have a set of brembos to go on the front and i checked them for clearance on my wheels. the evo 8 brmbos came on complete front legs, hubs, etc, so i put my wheels on them. i had to put 9mm of spacer to make the wheel clear the calipers. I was gobsmacked.

if i assume i have the 18"x7.5 +42 offset the 9mm spacer will make the offset +31 or +49. either way i think they are going to rub the arch when had cornering.
even if i did get them to fit i would have to get longer hub bolts to secure the wheels correctly.

does this sound right?

Wodjno
28-01-2008, 12:13 AM
I have measured the offset on my wheels with the tyres on /yes

I just cut 2 pieces of timber to the diameter of my rims. Then placed 1 either side of the rims. The i place a smaller piece onto the bolt face and then i was able to measure the offset..

Davezj
28-01-2008, 12:21 AM
yes i can see how that would give yu the total width of the rim but isn't the width measured on the inside surface of the rim that the tyre bead sits on, as in the picture on the thread i linked. measument i am talking about is labeled "rim width".

Edit:
but that doesn't matter, as the middle of the wheel is still the middle of the wheel as long as the rim tips are the same on both sides. which they have to be to keep the tyre on.

from the pic in linked thread i need to do the follow calc which is B-A=C
Back side of wheel - half rim width = offset.

bradc
28-01-2008, 12:28 AM
18x7.5" 35mm offset will be fine with 225/40 tyres. I know of a few members with 18x8 or 18x8.5" wheels with a 35mm offset and the same tyres with no problems, some of them have had to rub their guards a bit though at the back.


If your wheels are 42mm and you put a 9mm spacer on them, then they would become 33mm offset.

TBH it is probably better to sell those wheels and buy new ones that are designed with EVO 5/6 fitment in mind.

Wodjno
28-01-2008, 12:30 AM
yes i can see how that would give yu the total width of the rim but isn't the width measured on the inside surface of the rim that the tyre bead sits on, as in the picture on the thread i linked. measument i am talking about is labeled "rim width".

But as long as rim thicknes is equal !

It doesn't matter if you use 2 6" blocks of wood on either side of the wheel(as long as they are of equal thickness). Once you have measured the overall width, (Beit 200mm or 800mm) If you half these figures(100mm or 400mm) and then measure from bolt face to rim.. Lets say for arguments sake it is (75mm or 375mm) the offset measurement wil be the same.. ie: 100 minus 75 = 25mm or 400 minus 375 = 25mm.. So the off set is 25mm. And depending whether that is towards the front or rear of the whell determines a positive or negative offset..

Simply put: The offset is the distance from the centre line of the wheel to the bolt hole face..


PS.. Normally somewhere on the wheel it will have imprinted the offset.. Usually on the bolt face..

Wodjno
28-01-2008, 12:37 AM
Oh !!

And if you do need spacers give me a shout, as i have 3 or 4 sets kicking around in my boot..

Davezj
28-01-2008, 12:39 AM
cheers i did figure out what you meant in you previous post, it just took a little time to get my head round the measurent.
excellent advice
cheers Dave

EDIT:
thanks for the offer, but i think it might be rub city, with these wheels. i thought they had loads of clearance for the brembos, how wrong was I.

Wodjno
28-01-2008, 12:42 AM
cheers i did figure out what you meant in you previous post, it just took a little time to get my head round the measurent.
excellent advice
cheers Dave

EDIT:
thanks for the offer, but i think it might be rub city, with these wheels. i thought they had loads of clearance for the brembos, how wrong was I.

No worries..

If you do need spacers i think i've got a range between 3mm and 10mm.. :pimp2:

stuey
28-01-2008, 11:51 AM
As Already mentioned, you really want to try and get rims with the evo 5 - 9 as I bought 18x8.5 rims presuming they'd fit when i did the brembo conversion, but they didn't due to the design of the wheels, so had get new ones.
I'm suprised the don't say somewhere on the back of the wheels what the size & offset is as they often do..
You can always measure the offset by finding backspacing (as they use in the US) straight edge across the back of the wheel, then presuming you know wheels width the rest is easy (e.g. 8" rim with 5.25" backspace = 35mm offset)

Davezj
03-02-2008, 06:00 PM
well i got the wheel off and the measured the offset.
the rim is a 7.5" but measured with tyre on, on the outside of the rim it is 216mm and the backspece is 150mm so the offset is 42mm.

This i now realise that is why i have to fit a 9mm spacer to fit of the brembo's which will make it a 33mm offset. which is a bit more normal.

anyone know where i can get extra long hub studs to replace the originals as they will only catch five full turns, before the wheel is locked on tight.

Nick Mann
03-02-2008, 10:48 PM
Or could you get longer nuts? Sometimes it is possible to get nuts with a longer thin bit - so they screw in further before they hit the mounting face. Does that make sense? :inquisiti

Davezj
03-02-2008, 11:06 PM
yes it does make sense. i will have to look into whats is available. thanks for the ideas.
Dave