Rim's Offset

Hi guys..i just got a noob question about the meaning of the offset of a rim.
We always see some description about a wheel such as 18 x 8.0J OFFSET +55, what is the meaning of the 8.0J and the offset +55? i got some pictures here and they should be in different offset size and that 8.0J thingy.
I could pretty sure that those rims are in 18 inches, but is the S13 in 10.0J and the DC5 in 8.0J (Approx) and why should we care about the offset size?
if i want to fit brembo into my car, what offset or what J should i get?
Thx :p

http://i186.photobucket.com/albums/x...rkxd9180sx.jpg

http://i186.photobucket.com/albums/x...d9hondadc5.jpg

the offest is how far the centre mount is from the centre of the wheel.
so +55 means its 55mm towards the outside of the wheel from the centre line of the wheel.

the other part, 8.0j is how wide the wheel is in inches

Quote:

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Originally Posted by trism

the offest is how far the centre mount is from the centre of the wheel.
so +55 means its 55mm towards the outside of the wheel from the centre line of the wheel.

the other part, 8.0j is how wide the wheel is in inches

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so is it mean that the S13 is with 10.0J and the DC5 is with 8.0J (approx) according to the photo? does that affect of installing a brembo?

I still dun understand the meaning of Offset, is it a standard size of each car?
that means if the original spec is in +55, i would need to buy any rims with offset +55?

Usually for bigger brakes you require a lower offset.

For instants 45+ on 15 inch wheel will clear OEM caliper. But when you add endless caliper you need a 35+ or lower to clear caliper without using a spacer. Lower the offset the more dish, the further the wheel sticks out.

no thats not right!!

the bigger the brake, the more offset you need.

the lower the offset, the deeper the lip.

Ok from first had experience 39+ wasnt enough i needed 35+.

- or negative offset wheels

http://www.japanesenostalgiccar.com/...ims/sakura.jpg

+ or positive offset wheels

http://www.carrims.us/alloy-wheel-424.jpg

So most FWD cars come with +35 or +40 rims and by lowering the offset to +10, +20 or even a 0 offset will put more dish on the rim and poke it out of the gaurd more. (its not recommended to put a 0 or +10 offset on your FWD unless it is pretty modified, I only used them as examples)

so is that mean the photo (s13) that i have provided has a +10 or +25 (approx) offset? and DC5 with +55offset?

so with diff offset, could i still use my oem typr or i needa buy a new set of it?

Quote:

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Originally Posted by trism

no thats not right!!

the bigger the brake, the more offset you need.

the lower the offset, the deeper the lip.

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TheBob is correct, generally.

It really comes down to the ALL of the following: Wheel offset, size of wheel and the design of wheel.

Generally speaking, same wheel, same size, you'll need a lower offset to bring the spokes out further to clear the calipers.

http://i13.photobucket.com/albums/a2...heelOffset.jpg

Depending on the size of the brake. MOST brake upgrade kits require a lower offseted wheel. Spoon calipers for EG, EK and DC require 38 or less i think. But as Deano said, depending on the style of wheel. Its a try and buy type thing.

Quote:

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Originally Posted by DLO01

TheBob is correct, generally.

It really comes down to the ALL of the following: Wheel offset, size of wheel and the design of wheel.

Generally speaking, same wheel, same size, you'll need a lower offset to bring the spokes out further to clear the calipers.

http://i13.photobucket.com/albums/a2...heelOffset.jpg

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ok, so looking at that pic. the dotted line is the centre line of the wheel.

the further the mounting hub of the wheel (the red line) is towards the front (outside) of the wheel, the larger the offset. thats positive offset.

if it goes back to the inside of the centre line, thats negative offset.

did we clear that up?

now, so in order to fit bigger calipers you often need to push the spokes further outwards, and so you fit a larger caliper....

You should not look at it as the Red line that moves (the hub does not move). Rather it is the 'Wheel Centerline' that moves according to what offset the wheel is.

So in order to move the spokes 'outward' to clear a larger caliper the 'Wheel Centerline' will move toward the Red line, and therefore a lower value offset.