Upper and Lower Bounds for Wheels

[michaelpw97]

I am looking to get a new set of wheels, as the OEMs have become my winter set.
I still have my 18" square setup all season tires and so am looking to likely end up with a square 18" wheel setup as not to have to buy new summer tires.
What are the upper and lower bounds of specifications that will work with the 2019 GT2 AWD? In terms of Width, offset, bolt pattern etc? I know quite a bit about cars but very little about wheels, so all insight is appreciated thanks! Don't be afraid to tell me what I don't know!

 

[Snicklefritz]

225/45 is going to fit up to 8.5" wide rim. Offset should stay near the OEM +34 with 18" wheels. Bolt pattern won't change. Tell the people selling the wheels to find the best size in the look that you want. I'd never trust myself to buy based on what I read on the net. That's because the particular wheel can get into clearance trouble with variances in backspacing and spoke design, etc.

 

[Volfy]

For a square set up, the limiting factor is clearing the front struts. 18x8.5" is about the widest that will fit properly. By that I mean with an offset close to the stock 34mm. You can widen it to 30mm, but I would not go lower than that. You might be able to find some 18x9" wheels with ET30 that will clear the strut, but most probably won't.

You can go 25mm offset, but your scrub radius would start to be too far off from stock and might introduce handling issues, like mid-corner bump steer, especiallywith big fat wheel/tires. The wheels will also stick outside the fender line, which I personally think look rather retarded, but looks are a personal preference thing.

Rear wheel fitment is much more generous. Whatever clear the front will fit out back.

Lower bounds? Not really any. You can run pizza cutters if you want. My street daily setup is 235/45R18 A/S on 18x7.5 Genesis sedan rims. Quiet and superb ride quality. Turn-in not the sharpest but handles just fine for occasional cornering fun. I'm not into street heroics, so I optimize on what I care more about for road riding. I've got several sets of dedicated track wheels, for having "real" fun.

 

[michaelpw97]

For a square set up, the limiting factor is clearing the front struts. 18x8.5" is about the widest that will fit properly. By that I mean with an offset close to the stock 34mm. You can widen it to 30mm, but I would not go lower than that. You might be able to find some 18x9" wheels with ET30 that will clear the strut, but most probably won't.

You can go 25mm offset, but your scrub radius would start to be too far off from stock and might introduce handling issues, like mid-corner bump steer, especiallywith big fat wheel/tires. The wheels will also stick outside the fender line, which I personally think look rather retarded, but looks are a personal preference thing.

Rear wheel fitment is much more generous. Whatever clear the front will fit out back.

Lower bounds? Not really any. You can run pizza cutters if you want. My street daily setup is 235/45R18 A/S on 18x7.5 Genesis sedan rims. Quiet and superb ride quality. Turn-in not the sharpest but handles just fine for occasional cornering fun. I'm not into street heroics, so I optimize on what I care more about for road riding. I've got several sets of dedicated track wheels, for having "real" fun.

What about offset going the other way? for instance WRX wheels have the correct bolt patter and size (18x8.5 5x114.3) but the offset is like 55mm? What does that mean and how would it work with the stinger gt? 2021 Subaru WRX 18" OEM Wheel Rim W68851DC. Does this work? Would it be an issue with the brembos?

And thank you for your earlier response! I really appreciate it

 

[Volfy]

What about offset going the other way? for instance WRX wheels have the correct bolt patter and size (18x8.5 5x114.3) but the offset is like 55mm? What does that mean and how would it work with the stinger gt? 2021 Subaru WRX 18" OEM Wheel Rim W68851DC. Does this work? Would it be an issue with the brembos?

And thank you for your earlier response! I really appreciate it

Fair question. Too high an offset will definitely cause problems, not only fitment, but also handling issues as well.

(A bit of related background info) A lot of FWD (or FWD-based AWD) cars have high offset, as it helps minimize torque steer from the driving front wheels. With RWD, this is obviously not an issue. Even RWD-based AWD tends not to be affect as much, since torque sent to the front axle is generally limited.

So, is that WRX wheel okay to use on a Stinger? Answer is... yes, with a caveat. As is, that WRX 18x8.5 ET55 will most definitely not bolt on the Stinger front without hitting the strut and/or the Brembo. Now, put a 20mm spacer on, and the effective offset becomes 55-20= 35mm, which is within 1mm of the stock front ET34. It has a very high likelihood of fitting - and driving - just fine.

What then is the caveat? Well... I personally do not like any spacer thicker than 5mm. From there, you first get into a range of 5-15mm where the spacer is not thick enough to have built-in studs, and the stock studs are too short to have enough engagement with the lug nuts. That means you'll need longer studs. Not an easy retrofit. Plus, once you swap in longer studs, now you might have problem putting stock wheels back on, because the studs would be too long. Yeah you could switch to open-ended lug nuts, but you start to compound your problems - and the needed solutions.

Or you can jump up to 15mm or thicker spacers, which do have built-in studs. However, I am not at all a fan of running with thick studded spacers. Maybe you are okay with it. I am not. Hence the caveat.

Funny you should mention those WRX wheels... The Enkei RPF1 18x8.5 ET40 I just bought actually came from a guy that ran them on his WRX. I installed them on my Stinger with a pair of 5mm hub-centric spacers and extended lug nuts. Effective offset of 40-5=35mm is just about perfect.

 

[Snicklefritz]

I don't understand your math. Are those first two typos?

55-2= 33mm 55-15=30mm

 

[Volfy]

I don't understand your math. Are those first two typos?

Sorry... typing on my phone on lunch hour.

I just edited the post. Math is correct now.

 

[michaelpw97]

Fair question. Too high an offset will definitely cause problems, not only fitment, but also handling issues as well.

(A bit of related background info) A lot of FWD (or FWD-based AWD) cars have high offset, as it helps minimize torque steer from the driving front wheels. With RWD, this is obviously not an issue. Even RWD-based AWD tends not to be affect as much, since torque sent to the front axle is generally limited.

So, is that WRX wheel okay to use on a Stinger? Answer is... yes, with a caveat. As is, that WRX 18x8.5 ET55 will most definitely not bolt on the Stinger front without hitting the strut and/or the Brembo. Now, put a 20mm spacer on, and the effective offset becomes 55-20= 35mm, which is within 1mm of the stock front ET34. It has a very high likelihood of fitting - and driving - just fine.

What then is the caveat? Well... I personally do not like any spacer thicker than 5mm. From there, you first get into a range of 5-15mm where the spacer is not thick enough to have built-in studs, and the stock studs are too short to have enough engagement with the lug nuts. That means you'll need longer studs. Not an easy retrofit. Plus, once you swap in longer studs, now you might have problem putting stock wheels back on, because the studs would be too long. Yeah you could switch to open-ended lug nuts, but you start to compound your problems - and the needed solutions.

Or you can jump up to 15mm or thicker spacers, which do have built-in studs. However, I am not at all a fan of running with thick studded spacers. Maybe you are okay with it. I am not. Hence the caveat.

Funny you should mention those WRX wheels... The Enkei RPF1 18x8.5 ET40 I just bought actually came from a guy that ran them on his WRX. I installed them on my Stinger with a pair of 5mm hub-centric spacers and extended lug nuts. Effective offset of 40-5=35mm is just about perfect.

View attachment 84565

I can't begin to describe how useful this explanation is for me. I want to make sure I understand correctly. Offset is measured from the centerline of the wheel right? So a 35mm offset would mean that the mounting face is 35mm Towards the outside of the wheel from the centerline? And a 55mm Offset would be mounting 55mm towards the outside of the wheel from the centerline?

 

[Snicklefritz]

The bigger the offset, the closer to the suspension. So, for instance, that +55 would be crammed against your front strut. But a +-0 would have your outer rim exposed beyond the fender, i.e., "poke". The wheel with no offset, or negative offset, would also look very concave, which of course is a favorite look to hot modders.

 

[Volfy]

 

[Volfy]

BTW, a bit of trivia for ya. The "ET" commonly found stamped on wheels to indicate offset is an abbreviation for the German word: "Eipresstiefe".

Here in North America, it used to be much more common for the automotive industry to list "Backspacing" of a wheel. That measurement makes it easier to compare and visualize clearances different aftermarket wheels might have to a car's suspension components. The emphasis thus is purely on FITMENT. Often times, the question is: what is the widest wheel/tires I can throw on this here hotrod? Kinda sad that this trend persists to this day.

Over in Europe (and elsewhere), narrow and winding streets dictated a greater emphasis on a car's precision handling. For that, it is much more important to know where the center of the tire's contact patch sits relative to the kingpin axis. That distance BTW is called the Scrub Radius. So, the suppliers for European car makers have to list what their clients want to know, in the terms they prefer to use. That's why ET was adopted.