R34 Gtt Wheel Offset Advice

[niZmO_Man]

get some flares on them, or wider guards haha

[Peeeeetaaah]

Hi guys, planning to get 18x9 +25 in fronts and 18x10 +25 in rears been reading the whole thread and cant really find anything

 

Anyone know if these will fit a r34 gtt with no scrubbing or guard work needed?

[Milkmun]

On 25/01/2025 at 11:46 PM, Peeeeetaaah said:

Hi guys, planning to get 18x9 +25 in fronts and 18x10 +25 in rears been reading the whole thread and cant really find anything

 

Anyone know if these will fit a r34 gtt with no scrubbing or guard work needed?

Depends how low and tyre size. Should fit with natural camber, skinny tyres and rolled guards.

[Peeeeetaaah]

9 hours ago, Milkmun said:

Depends how low and tyre size. Should fit with natural camber, skinny tyres and rolled guards.

Thanks for the info mate was thinking 255/35 rears and 235/40 fronts

[AdiR34]

Being the top Google search result for R34 wheel-related inquiries, lemme throw down my experience.

I calculated that 100mm from hub face to wheel face is about the perfect fitment for my ENR34 sedan. 

I've been running 18x8.5s, ET35, with a 1" spacer. So, 8.5in to mm = 216mm. 216/2 = 108mm. 108-35 = 73mm. 73+ 25 (1" to mm) = 98mm. 

If you wanna get close to this on dif widths, here are the offsets you'll want:

9" - ET around 15mm

9.5" - ET around 20mm

10" - you're crazy, but ET around 30mm

All these should fit perfectly on a non-widebody, non-GTR Skyline. Note that it's probably the absolute max, and you're probably better off running a couple degrees of camber in this config, but it looks great, super flush.

[Kinkstaah]

This is actually a really good way of measuring what wheels fit. If only there was a similar measurement between hub face and suspension :p

That said, it's probably pretty simple to actually measure it all with the wheel off the car for the rear. The front is a bit more complex but.. 

[GTSBoy]

What can't be done with a little bit of decking board or similar timber bolted to a hub flange via 2 wheel nuts is not worth talking about.

[Kinkstaah]

Perhaps, and it's deceptively similar. I was yesterday days old when I first heard anyone mention that the default guards have exactly XXXmm space.

No more "is 8.5+37 going to be flush/fit, or will it poke? how much? 9.5 +16.9?" etc.

Can just do maths and subtract from 100 - Shit, Wheels should have this measurement stamped on them.

"This wheel extends 74mm from the hub in one direction and 57mm in the other"

This is a far better system than offset, inches, and backspacing.

 

[GTSBoy]

1 hour ago, Kinkstaah said:

"This wheel extends 74mm from the hub in one direction and 57mm in the other"

Isn't this what everyone immediately sees in their mind's eye when someone gives them a total width number and an offset?

[Kinkstaah]

Given by the sheer number of questions about offset, absolutely not.

If you had the information formatted this way:

Space from R34 GTT hub to outer arch = 100mm
Space from R34 GTT inner hub to nearest suspension arm = 90mm. (making this up)

Buying a wheel that was advertised as

Enkei RPZ5
Diameter 18in
Width 9
Distance to arch = 84mm
Distance to suspension arm = 76mm

100% of people would know instantly if it fits. They would absolutely also know instantly how close it fits too, and no questions would need to be asked. You would know you would have 16mm from the guard and 14mm from the suspension arm.

[GTSBoy]

1 hour ago, Kinkstaah said:

If you had the information formatted this way:

Space from R34 GTT hub to outer arch = 100mm
Space from R34 GTT inner hub to nearest suspension arm = 90mm. (making this up)

And....if that could be true for all R34 GTTs, then it might be good. But in reality it is not really any better than my standard instruction to "go out and have a look at it yourself, and wave a tape measure around" etc etc, because as soon as you have any adjustable arms, or coilovers with smaller diameter springs, or tyres that have any bulge that goes out further than the rim, etc etc, then the simple version of the information is still potentially misleading.

Plus, nothing in this is static. Everything is moving. At the rear the wheels swing inward at the top as they go up, so the clearances on the inside change as the suspension is compressed. At the front it's even worse. And then you have the difference in absolute wheel position in the arch can move around more, or less, depending on how compliant the bushes are. If, like me, you have sphericals on the front caster rods (and on the FUCAs also, but these are probably less dominant when it comes to wheel position), then your wheel will swing forward/backward less under loads than some others, but as well as up/down, as well as steering angle.

You end up having the simple numbers with 17 caveats/footnotes for each.

Edited February 7 by GTSBoy
Had to finish a half finished thought that didn't make it out the first time

[Kinkstaah]

Sure! But you at least have simple numbers instead of 8.5 inches +/mm, relative to your current rims you do maths with as well, and/or compare with OEM diameter, which you also need to know/research/confirm..

[GTSBoy]

But offsets are simple numbers. 8" wheel? Call it 200mm, near enough. +35 offset? OK, so that means the hub face is that far out from the wheel centreline. Which is 2s of mental arithmetic to get to 65mm to outer edge and 135mm to inner. It's hardly any more effort for any other wheel width or offset.

As I said, I just close my eyes and can see a picture of the wheel when given the width and offset. That wouldn't help me trust that a marginal fitment would actually go in and clear everything, any more than the supposedly simple numbers you're talking about.

I dunno. Maybe I just automatically do numbers.

[Kinkstaah]

It still combines inches with mm, especially when you have .5 inches involved, and mm and inches that can go in either direction.

This would give a clear idea on both sides of the rim, right away, with no arithmetic. Even better if somebody gives you the dimensions of the arch of multiple cars. i.e GTR may be 125mm, a A80 Supra may be 117mm, or something along those lines.

Yes, you can 'know' that going from a 10in rim to a 10.5in rim with the same offset moves both sides about 6mm, but you still have to 'know' that and do the math. Often it's combined. People are going from 9.5 +27 to 10.5 +15.

You may do the math to know it, but if it was going from (I had to go look it up to be sure) 241mm/2 - 27 - 93.5mm from the center line to (more math) 266/2 - 15 (118mm) from the center line.

Versus 93mm vs 118mm. It's right there. If you know you have a GTT with 100mm guards you can see right away that one is close to flush and the other absolutely won't work. And when someone says "Oh the GTR is 120mm" suddenly you see that the 10.5 +15 is about perfect. (or you go and buy rims with approximately 118mm outward guard space)

I think it's safe to say that given one of the most common questions in all modified cars is "How do offsets work" and "How do I know if wheels will fit on my car" that this would be much simpler...

Of course, nothing will really change and nobody is going to remanufacture wheels and ditch inches and offset based on this conversation :p We'll all go "18x9+30 will line up pretty close to the guards for a R34 GTT (84mm)" but 'pretty close' is still not really defined (it is now!) and if you really care you still have go measure.

Yes it depends on camber and height and dynamic movement, but so do all wheels no matter what you measure it for.

[GTSBoy]

I think my main complaint with your idea is that there is a veneer of idealism spread across it. You want the simple numbers to make it easier, but all they will do is make it easier for someone to come to the wrong conclusion because the fine details will kick them in the nuts.

As it is right now, the tiny bit of arithmetic is NOT the obstacle to understanding what will fit and what will not fit. The reality of trying it is what determines whether it will fit.

If you had a "standard rule" that R34 GTT guards have that magic 100mm space from the hub face to whichever side you were worried about, and someone said "excellent, this wheel is only 98mm in that direction, I'll just go spend $4k on them and jam them on my sick ride".....they would just as likely find out that the "standard rule" is not true because the rear subframe is offset to one side by a fairly typical (but variable) 8mm on their car and they only have 92mm on one side and 108 on the other.

[No1]

Heres another fitment photo. redrilled the pattern to 5x112, and threw my audi´s rims on. had to touch the upper control arms with grinder, because the "sharp corner" was sticking about 2-3mm on the tire path.
i have the "fender lip" mostly cut off, otherwise these (too) would contact with it.


20x9.5 ET25 rear    265/30
20x8.5 ET20 front    255/30

they are temporary, and look too big for the chassis. searching for 19s to it.

[EddieR34GT-X]

I've replaced the front brakes of my NA to 324 brembos and 350z calipers: i'm going for 225/40-18 up front and 245/35-18 in the back. I have Rays 7.5*19 ET35(225/35) in the front with 5mm spacers otherwise the calipers "lock up/ won't rotate". When i use the calculator i come up with 8*18 ET30 for 225/40...... but not sure i get problems with the calipers. Anyone riding around with 18 inch. that can confirm "that it'll fit"? In the back it's 7.5*9 ET30 (245/30) with the 5mm spacers, but there is no problem with the standard small brakes, so i want to take 8.5*18 ET25 (245/35).

Edited Wednesday at 06:45 PM by EddieR34GT-X
Pictures added

[GTSBoy]

Whether the brakes will clear the back of the spokes comes down to the specific wheel, as well as its dimensions (ie 18x8 or whatever else size). You can have 2 different wheels of the same size and one will clear and on the other the spoke design will not clear.

So your question "Anyone riding around with 18 inch. that can confirm "that it'll fit"?" cannot be answered in a meaningful way. You need that person to be using the same wheel you want to use.