Wheel Offset Maths For A R33 Gtr

[tjandriesen]

I'm looking at buying a set of used wheels from another forum member and want to make sure I'm getting the offset maths correct

The current stock wheels are

F 17 x 9 - 30 offset

R 17 x 9 - 30 offset

the wheel I'm looking at are

F 17 x 8.5 - 28 offset

R 17 x 9 - 37 offset

Using the handy calculator I found on another post (http://marksink.com/tire_wheel_offset/offset.html), I've worked out that

The front wheel will have 8mm more clearance from the strut housing and will be 4mm into the body

The rear wheel will have 7mm less clearance fom the strut housing and wont change relative to the body

If I'm thinking about this correctly, the fronts are no problem. My question is the rears. Is 7mm a critical amount? How do I measure to check?

[blind_elk]

If you have a GT-R, then you DO NOT want different sized wheels on the front compared to the rear. Otherwise you will be (re-)posting a(nother) thread that your AWD is misbehaving.

[tjandriesen]

If you have a GT-R, then you DO NOT want different sized wheels on the front compared to the rear. Otherwise you will be (re-)posting a(nother) thread that your AWD is misbehaving.

Not that you say that, the logic is pretty obvious, as is why all 4 wheel on my car are the same size. Thanks!

[wrxhoon]

I'm looking at buying a set of used wheels from another forum member and want to make sure I'm getting the offset maths correct

The current stock wheels are

F 17 x 9 - 30 offset

R 17 x 9 - 30 offset

the wheel I'm looking at are

F 17 x 8.5 - 28 offset

R 17 x 9 - 37 offset

Using the handy calculator I found on another post (http://marksink.com/tire_wheel_offset/offset.html), I've worked out that

The front wheel will have 8mm more clearance from the strut housing and will be 4mm into the body

The rear wheel will have 7mm less clearance fom the strut housing and wont change relative to the body

If I'm thinking about this correctly, the fronts are no problem. My question is the rears. Is 7mm a critical amount? How do I measure to check?

Your calc is partly correct for the fronts assuming the offsets are +28and +37( not-28 and -37). So fronts will be 2mm further out lees 6 mm because they are 12mm narrower( half of that) so the net effect will be 4mm further in but only 4mm further away from the struts.

I dont know how you worked the reats but its totally out. They will be sitting 7mm to the inside of the guards and 7 mm closer to the struts.

Why would anyone want to use narrower rims on a GTR? Why would you want to use different size wheels ?

[n15m0]

The above offsets u quoted are more suited to RWD GTSTs. You have a GTR, take advantage of this!! Due to wider guards, GTRs can run offsets between +15 to +20 depending on wheel width. Something that us, non GTR owners envy.

Smaller offset wheels also normally translate to more dish and aggresively angled spokes which make them look much hotter than if the same wheel was on a GTST...if that makes sense..

Oh and yeah...for a GTR, try and run 4 of the same width n offset wheels all round.

[salad]

As long as you get tyres that are the same very similar rolling diameter, you will be fine. Dont forget that new tyres come with 8mm tread. So there is potentially 16mm difference in rolling diameter when you buy a pair of new front tyres. That is less than the difference between a 235/45R17 and a 245/40R17.

But getting the same size tyres all round would probly be a better idea.

Buy those wheels and give me your old wheels