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Finding the right offset..

sidewaymambo
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sidewaymambo Mentor

sidewaymambo

Posted
Posted

Hi, Guys

Need some opinion from you, I'm using a pair of 6 pots brake clipers at front, however in order to clear the brake clipers, I use 20mm spacers each side and manage to have 10mm clearence between front clipers and spokes, now I am consider to purchase right offset for the front and rear, just wondering what is the right offset for 17" and 18 " in order to keep this pair of clipers, and right offset for rear (still use standard rear cliper) to work with front.

I am not sure the Brambo use in R33 GTR, I was thinking purchase stock GTR rims..

Thanks

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https://www.sau.com.au/forums/topic/38943-finding-the-right-offset/
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  • 2 weeks later...
Duncan Grand Master

Duncan

Posted
Posted

check out this thread: http://www.skylinesaustralia.com/forums/sh...ighlight=offset

It looks to me like the offset you need is the same as your current wheels, +15-20mm. If the offest is on your wheels then it should be easy.

But offset relates to the width of the rims, not the diameter, so it doesn't matter if they are 17s, 18s or 13s :rofl:

  • 4 weeks later...
sidewaymambo Mentor

sidewaymambo

Posted
  • Author
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thanks Duncan,

I could not found the offset listed anywhere on the rim..when i bought the car years ago, it comes with 20mm floating spacers to clear (5mm) the stock front caliper, if standard R33 GTST rim offset is 40, does it mean my current rim is +20? I was wondering a new set with +40 should clear the 6 pots caliper now..

Duncan Grand Master

Duncan

Posted
Posted

yes, yes, and not sure! but if you know someone with +40 rims, try and bolt them up!

Like I said before the offset is affected by the width of the rim. What width are your current rims? We are talking about front, right?

According to Meggala's site you need:

8inch wide = +35 offset

7inch wide = +33 offset

and presumably 9inch rims would need +38 offset.

But that is all for the standard brakes, it depends if your brakes stick out further than standard ones?

sidewaymambo Mentor

sidewaymambo

Posted
  • Author
Posted

Hi, Duncan

just do a measure, the 6 pots caliper is about 14cm wide, which is same as stock nissan 4 pots, so I assume maybe the standard offset should clear the caliper..

So..if I am looking for 17x8 front and 17x9 rear, what will be the correct offset? thanks

Ronin 09 Grand Master

Ronin 09

Posted
Posted

Hi guys,

**Please note that this is my understanding, and could be COMPLETELY wrong**

I don't know if this will add to your discussion, but I don't think wheel offsets are quite as simple as adding the difference between the offset of the existing wheel to the depth of the spacer plate. Only in the case of the exact wheel diameter and width (say 17x8) will this work correctly.

Consider the diagram 1 below. Assume that the wheel diameter is 17”, width is 8”.

The offset is the distance (in mm) from the centre line of the rim. Therefore in my shitty diagram, this rim has a positive offset of 35 mm.

Inner edge of rim to centre line = 4” = 101.6mm

therefore, the positive offset of 35mm will place the inner edge of the rim:

136.6mm from the hub.

Now consider the second diagram, where I have upgraded to a 18” rim, width 10”.

To ensure that the tyre (assuming that the rolling diameter remains the same as we have dropped the aspect ratio) does not foul the inner guard, or sit any closer to the inner guard (and also assuming that there is enough room at the outer guard to fit this big bastard), we calculate the offset as follows:

Inner rim to centre line = 5” = 127mm

Therefore, to maintain a overall inner rim to hub distance of 136.6mm

We will need a positive offset of 9.6mm (say 10mm)

However, in the real world, the inner guard will be able to swallow some of this additional rim width, so we may be able to go to a +/- 0 offset with the inner edge of the rim moving 10mm closer to the inner guard.

So, if you bothered to read this far, and I’m wrong, don’t flame me too much. I actually thought this through a bit. Hope that adds to the discussion.

PS sorry about the smudges – I am left handed!

edit: the LHS of the pics is the inside of the wheel

Ronin 09 Grand Master

Ronin 09

Posted
Posted

sidewaymambo - the offset will be printed on the rim, cast somewhere into the rim.

It may be on the back where it bolts onto the hub, usually something like 17 x 8JJ +30; the offset is the last figure (which may be negative)

If you can get this, I may be able to help you figure your correct offset :thumbsup:

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