R32 GTR offset (again) - SK input?

[Ronin 09]

Hi again.

I have devised my tyre offset calculator.

I want to know if a 9.5 inch wide +12 wheel will fit (not stick out or foul suspension).

Previously Sydneykid has said that the race car R32 GTR runs 8 inch wide, +35 rims with a 40mm spacer. This would be equivalent to a 8 inch wide rim with a -5mm offset. See here

Plugging this stuff into my calculator, we get:

8 inch wide, -5mm offset:

distance to inner edge of rim 9.66cm

distance to outer edge of rim 10.66cm

9.0 inch wide, +30mm offset (std R34GTR offset):

distance to inner edge of rim 14.43cm

distance to outer edge of rim 8.43cm

9.5 inch wide, +12mm offset:

distance to inner edge of rim 13.265cm

distance to outer edge of rim 10.865cm

9.5 inch wide, +22mm offset:

distance to inner edge of rim 14.265cm

distance to outer edge of rim 9.865cm

What I'm asking is

1. does anyone run volks in 18x9.5 +12 on their R32GTR and does it foul inside or outside at all using say a 265/30/18 (or is this a R33 / R34 GTR offset)

2. does anyone run volks on 18x9.5 +22 on their R32GTR and does it foul either inside or outside.

Cheers for the help, want to know before I shell out on rims.

[j-plus]

Firstly, do not own R32 GTR but have fitted similar sized wheels several times.

The latest wheels I have test fitted to R32 GTR were 18 x 10 (+12) - only half an inch wider than the 18 x 9.5 (+12) you are referring to.

The end result was they stuck out from the guards ~10mm - therefore, your 18 x 9.5 (+12) will stick out from the guards ~4mm (absolutely perfect in my eyes!).

There will be NO internal clearance issues. I know this 1. from experience and 2. from simple measurements - compare the internal differences betweeen BNR34 wheels (which are known to fit by everyone - I have also fitted these) and the 18 x 9.5 (+12)... BNR34 wheels sit ~12mm further in towards the suspension than your proposed 18 x 9.5 (+12).

I would be inclined to run 245/40/18 if purchasing these 18 x 9.5(+12) for ease of fitting.

Secondly, simple calculations tell us that an 18 x 9.5 (+22) will sit in 10mm externally and internally when compared with the 18 x 9.5 (+12). Therefore, just marginally inside the guards and almost the same internally when compared with BNR34 wheels (see above). I can't comment on tyre selection in this instance.

Also, can you please provide a link to these offset calculators you use. There seems to be a difference between punching some numbers in and reality.

Cheers,

Jeff.

[Ronin 09]

Thanks Jeff.

The 'calculator' is a simple spreadsheet that I wrote some formulas in. I'm pretty sure they are correct, based on my understanding of offsets, but if my understanding is wrong, then maybe the sheet doesn't tell the story.

It's attached if you're interested.

***note i had to change the extension to ".pdf" in order to be able to upload it. To use it, save as, and change the file extension to ".xls"***

cheers, Marcus

Also, can you please provide a link to these offset calculators you use. There seems to be a difference between punching some numbers in and reality.

[j-plus]

Marcus,

Couldn't open the attachment - sorry if I sounded a little harsh re: your calculator - not meant in that way!

Your understanding of offsets I'm sure is sound, and nowadays most people have a decent grasp on the subject. However, one thing most people don't realise is...

...a 9 inch rim is not 9 inches wide!

If you actually measure the width of a "9 inch rim" (or any rim for that matter) - you will notice it is actually ~10 inches wide. A good rule of thumb is to add 1 inch to the width of a rim (12.7mm inside and outside) to calculate the offset. Your results (whilst not being 100% accurate) will be within a couple of mm's.

(I will locate some pics and post them for a visual explanation)

I am by no means an expert, but dealing with these issues every other day has allowed me some level of competence.

Bottom line is the 18 x 9.5 (+12) will stick out a touch (my preference) and the 18 x 9.5 (+22) will be a pretty snug fit.

Cheers,

Jeff.

[Ronin 09]

don't worry jeff - no offense taken. Always willing to learn by asking!

if you can post some example pics that'd be appreciated!

[lwells]

If you look at Ray's fitting chart for the TE-37, you'll notice that they actually warn that the 18x9.5 +22s (which is the recommended offset) stick out from the guards

http://www.rayswheels.co.jp/cgi-bin/cgi2/m...E37&inchIndex=5

Lucien.

[j-plus]

yes, the front guards on a BNR34 : )

[lwells]

yes, the front guards on a BNR34 : )

I'm note quite sure I see your point?

LW.

[williamsf1]

ok marcus I took some measurements of my R32 GTR with the R34 GTR wheels...

on the rear which you asked me to measure, I found that it was about 22mm from rim edge to furthest part of the guard (i.e. the centre looking down....)

here are some pics to help with a tape measure as a guide....

oh and yes car was just washed rusty discs!! and no I didnt gutter wheels.... previous japanese dude thrashed these wheels on some circuit.... tyres are totalled!

anyhow I hope this helps you out.....