G50 Wheel offset and size standards

[ceningolmo]

This has been a question often enough that it probably wouldn't hurt to just post some standards that people can work from.

The stock wheel is 15x6.5 +45 with 215/65/15 tires.

I just did some quick and dirty measurements on the front and rear wheel wells. There appears to be about 2.5cm space between the outside edge of the wheel well (at the top where it points out the furthest) and the inside clearance in the same spot.

BTW - for terminology sake... is this referred to as the fender, but the upper internal area is actually the wheel well?

I ran a plumb down from the outside of the fender/wheel well and measured the space between that line and the wheel. That space was about 5.5 - 6 cm. Subtract the 2.5cm thickness to the internal clearance and that leaves about 3 - 3.5 cm (call that 30 - 35 mm) additional outside clearance that is available beyond the outside edge of the stock wheel.

I did not measure inside clearance...I will leave that for someone else to do.

Using the calculator I often recommend...http://www.wheelsmaster.com/rt_specs.jsp

If we put in the standard wheel dimensions on the left and compare offsets from larger wheel options on the right...figure an additional 30-35mm of outside clearance to play with.

255/40 is probably the ideal tire ratio on an 18" wheel as it will match with the original total wheel diameter exactly (as Maxnix has frequently pointed out). So, assume that tire for the 18" wheel calculations...I am calculating 18's because it seems to be the most common.

Using the 255/40 on an 18" wheel... provided the wheel width is anywhere between 7" and 10.5" the offset should be in the +30 & +35 depending on how close you want to get to the limits.

Using the 245/45 tire on an 18" wheel...provided the wheel width is between 7" and 10.5" the offset should be between +25 & +30.

In both cases this seemed to leave plenty of room for inside clearance as well. But, someone might be able to work up some actual measurements for us on that.

[Rex]

For visual reference

18x8.5 +35 with 245/45's on the rear of a lowered (Eibach's) G50


18x7.5 +35 with 245/45's same car


18x7.5 +35 with 245/40's


Some diagrams to help "visualize" the terms and references.

[ceningolmo]

Wow... that is really handy! Thanks Keith!

[maxnix]

Using the 255/40 on an 18" wheel... provided the wheel width is anywhere between 7" and 10.5" the offset should be in the +30 & +35 depending on how close you want to get to the limits.

Using the 245/45 tire on an 18" wheel...provided the wheel width is between 7" and 10.5" the offset should be between +25 & +30.

A static test fit of the 18x9 +35mm Superleggera with 255/40 PS2 on my G50 (all stock) would suggest that +30mm might push the wheel too far out towards the fender. Not conclusive, but even the technician said he would like to see an offset closer to 40mm.

There is a forged 18x9 wheel with a 42mm offset I hope to try to fit in the future. But if not, I would be cofortable with a +35mm or maybe even a +34mm wheel, but nowhere near anything closer to the fender than +30mm.

We did not check at full lock where AZHitman says he has some rubbing with his 265/40 on 18x18 +40mm(?).

[VIP Q45t]

Sorry to bring this thread back from the dead. I tried searching and couldn't find any conclusive facts that I am looking for.

I would like to know if 18x7.5 rim that has a +42 offset, with 225/40 tires would fit on my lowered G50 with out any rubbing?

[maxnix]

Well, you need to read this thread and the tire sticky in Infininti General and your Owner's Manual a little more diligently.

They will fit, but they will not be safe with a load rating of 88 nor even 92 for an XL tire. Minimum OEM load rating is 95.

You will have to go to a 235/45-18 that is XL rated for a sufficient tire, and even then the 7.5" wheel with is the minimum allowed.

[VIP Q45t]

Okay thanks maxnix.I was just curious because those rims are from my other car. I noticed the bolt patter are the same, but I wasn't sure if it would rub.

[VIP Q45t]

I just seen these rims up for sale. I was just curious if these would fit on my Q45? And would I have to roll fenders, use spacers?

The specs are 18X8.5 +23 18X9.5 +30 5X114.3

[maxnix]

There are some BBS LM for sale at one of the former GTR importers that will fit. +23 mm is probably a little agressive in front. Might work, but it will be very close to the fender.

[Rex]

I just seen these rims up for sale. I was just curious if these would fit on my Q45? And would I have to roll fenders, use spacers?

The specs are 18X8.5 +23 18X9.5 +30 5X114.3

http://i37.tinypic.com/amse4z.jpg

Based on the "offset calculator", the fronts would stick out 6 mm more than mine (did), but the rears will stick out 11 mm more.

Depending on the tire size (I don't like to run stretched), you might get away with no changes, but I'm thinking you'd need to roll your fenders.







The inner front clearance

BBS RGR 18x9 +35 245/45/18's

[VIP Q45t]

Okay thanks rex and maxnix. I guess I'll have to pass on those rims.
Modified by VIP Q45t at 8:05 PM 9/4/2008

[TBrack]

dude those would fit nice, maybe a little minor modding but nothing too hard!

[VIP Q45t]

I tried using that tire guide thing. But I doesn't really tell me if it will fit or not. How much play do I have (from stock rims) for the aftermarket rims to fit? Whats the farthest out the rims can go and the closet it can go to the suspension?

Well I have been searching around for new rims. I came accross these. But once again I'm not sure if they will fit. 19x8.5+30, 19x9.5+36

[sessionsg50]

I tried using that tire guide thing. But I doesn't really tell me if it will fit or not. How much play do I have (from stock rims) for the aftermarket rims to fit? Whats the farthest out the rims can go and the closet it can go to the suspension?

Well I have been searching around for new rims. I came accross these. But once again I'm not sure if they will fit. 19x8.5+30, 19x9.5+36

Just wanted to reply to your concern. The answer basically boils down to "how" you would like the wheels to fit on the vehicle. From looking at the specs through my "standards"-I can make the wheels fit~No problems at all!! Well, it all depends on whether if you are willing to stretch the tire, add some negative camber and maybe do some mild rolling of the lip of the fender. I currently run a 19x9.0 +11/19x10.0 +11 on my G50, so those specs (19x8.5+30, 19x9.5+36) are mild from my mind set. Just wanted to give you some idea!

[Rex]

dude those would fit nice, maybe a little minor modding but nothing too hard!

I agree.

Of course if you want to run a 265 or 275 on the rear, then you may have some trouble. And personally for me, that's the reason to have a >9" rear wheel.

[maxnix]

Stretched tires and excessive negative camber are never a wise choice.

Isn't this thread basically for posting working examples, not general inquiries?

[thejapino]

Remember, a stock height Q vs. a lowered Q will have very different camber #'s.

The more you lower it, the more negative camber is added. The more negative camber you have, the more the top of your wheel tilts inward. So if a wheel will stick out a few mm. at stock height, you can bet the top of the wheel will start sinking into your wheel well once you start lowering it. You could adjust this with aftermarket upper control arms of course.

Here's a G50 fitment thread that shows you a whole spectrum of wheel fitment, from stockish to aggressive.zerothread?id=223195

[Rex]

... Isn't this thread basically for posting working examples, not general inquiries?

I think this thread (below) is the one that is supposed to be "working examples".

Here's a G50 fitment thread that shows you a whole spectrum of wheel fitment, from stockish to aggressive.zerothread?id=223195

My examples are on a Q using Eibach lowering springs.

[mista808]

I just seen these rims up for sale. I was just curious if these would fit on my Q45? And would I have to roll fenders, use spacers?

The specs are 18X8.5 +23 18X9.5 +30 5X114.3

they will fit. for one, they are 18's, and the width are 8.5 and 9.5. the fronts will fit fine with no mods, the rears, itll be close... if anything, you might just have to roll the lip a little bit. but they will fit. i was running 19x9 +25, 19x10 +25, and i only had to roll the rear lip so slightly, but i rolled it flat. from 18" rims to 19" rims, you gain at most a 1/4" of clearence if the offsets were the same and if the top of the rim were to sit right flush with the fender (get what im trying to explain?)... anyways, i think they will fit fine...btw, im lowered on cut springs, front slightly rubs whenever i take the turns too fast...

[maxnix]

they will fit. for one,........ anyways, i think they will fit fine...btw, im lowered on cut springs, front slightly rubs whenever i take the turns too fast...

If that doesn't give one serious pause, not much else will.

[Pranil]

I just seen these rims up for sale. I was just curious if these would fit on my Q45? And would I have to roll fenders, use spacers?

The specs are 18X8.5 +23 18X9.5 +30 5X114.3

they will fit. for one, they are 18's, and the width are 8.5 and 9.5. the fronts will fit fine with no mods, the rears, itll be close... if anything, you might just have to roll the lip a little bit. but they will fit. i was running 19x9 +25, 19x10 +25, and i only had to roll the rear lip so slightly, but i rolled it flat. from 18" rims to 19" rims, you gain at most a 1/4" of clearence if the offsets were the same and if the top of the rim were to sit right flush with the fender (get what im trying to explain?)... anyways, i think they will fit fine...btw, im lowered on cut springs, front slightly rubs whenever i take the turns too fast...

Hey, So what size tires did you have on the 19's?