Apex Wheels

This is a fitment we are looking into, shoot me a PM with your name and email address and I will get you added to the list of 8Y RS3 customers wanting a fitment from us.

- Brandon

Apex Wheels

This topic has popped up multiple times in a few of our threads, so I want to take a minute to provide a more detailed response.

We're all about working with enthusiast communities on niche projects that solve pain points. We’ve made numerous ultra niche wheels to date, and we've been motivated for quite some time now to add a 19x8.5" ET54 front wheel fitment to our line up to cater to this application. I can’t tell you how many times it’s been discussed internally.

As many of you know, we already offer 19x10.5" ET44 and 19x11" ET45 rear wheel fitments, so releasing the fronts would provide 718 non-GT4 and 981/GT4 owners respectively with affordable and accessible solutions compliant with SCCA street class rules.

So what’s stopping us? In short, brake clearance. The slim width and high offset of a 19x8.5" ET54 creates some issues/barriers from an engineering standpoint - only because we are focused on delivering wheels without compromise. The spoke design featured on our forged wheels are highly optimized for strength and weight. We get a ton of added stiffness from our narrow but deep spoke profile which is only possible because of the custom motorsport blanks we designed. This depth makes great brake clearance hard because it hogs a lot of space, but if we made the spokes shallower we would be sacrificing a ton of stiffness. Since stiffness is not measured/publicized, other companies commonly release thin/shallow/floppy spoke profiles that lack stiffness, while touting the generic strength of “forged” to convey strength. We’ve done testing, and those forged wheels don’t even match the strength or stiffness of our flow formed wheels.

At the end of the day, we don’t want our RS wheels to compromise on what the line stands for. The Sprint Line is made up of 2 designs right now, but there are more designs queued up in development that may give us the clearance needed with this conservative wheel width/offset. We’re working through all of that now.

We’re committed to this application, and we’re not out to just make a quick buck. Hopefully this sheds a bit more light on the topic and how decisions are made at APEX behind the scenes.

- Ryan

unclemat

^ Thanks for the explanation, it's certainly confusing to a layman to read that 0.5" makes such a big difference...

But I certainly like to hear the wheels are strong and not compromised.

Apex Wheels

From a customers perspective we can totally understand how a 1/2" change in wheel width doesn't seem like a whole lot, but as Ryan mentioned, it is the combination of slim width AND high offset that ultimately causes a problem. Our deep spoke designs could work in a 19x8.5" ET44 which would put the face of the wheel in the same spot as our 19x9" ET50, but an ET44 wouldn't be SCCA street class legal. If you reference the image below of our 19x9"ET50 on the front of a GT4, you can see that our engineers have designed the spokes to be as deep as possible while still clearing the calipers. If we move the face of the wheel 10mm inward towards the brakes, there would be contact.


- Brandon

TRZ06

Too bad the 20"s are not offered in stock ET's. They would be a cheaper alternative to the BBS-SI-R, but I spent a lot of money on suspension and set-up and don't want to alter from stock ET.


So it looks like I will wait for the BBS's to become avail. again

Montaver

The rear is the same as stock, the front will be better with wider track width and wider wheel to support the tire. There is zero downside to their offsets and all upside.

TRZ06

But how does that play into bump-steer, understeer/oversteer balance, scrub radius, steering feel?

One thing I have found out about this car with all the work and set-up I have done over the last year is that this chassis is VERY sensitive to changes.

Reedy

Which ones are the SI-R model? I can't even find a reference to those anywhere on the BBS website, let alone a place to buy them. CI-R's look good but they don't even list them with the Porsche bolt pattern, let alone offsets.

The only BBS wheels that I can find anywhere that matches stock GT4 offsets is the FI-R.

I still have a set of Oz Racing wheels on order but I have been waiting for 3 months and there is still no sign of them even shipping. I am this close to cancelling that order entirely and going for a set of these.

TRZ06

Sorry, I meant the FI-R, I just got too excited typing, lol. They look amazing too, but they are not cheap and they take a long time to get.

Montaver

Less understeer due to the wider track, more sidewall support for the tire. Steering feel unlikely to be any difference.

I go between stock offset wheels and my track wheels regularly, the track wheels feel better. I believe I read somewhere the GT4RS comes with ET55 fronts for the aforementioned benefits. Many manufactures go with very conservative offsets for regulatory reasons, not performance. Something to do with snow chains in Germany.

Montaver

Just get the Apex. Perfect offsets, tons of support, aesthetically pleasing. If they bend beyond repair they have a track replacement program as well. The only negative is it took them so long to support the GT4 platform!

I have had multiple sets of Apex in the past. If I didn't already have a set of wheels I would get them, and if they had been available when I got mine I would of gone straight to Apex.

TRZ06

I believe they did too, but then they also tuned/calibrated everything else around that so everything stays in harmony with each other.

Regarding the sidewall support... Why is that more supported, what makes it so?

Montaver

Consider that Porsche expects users to add shims (another reason why the stock offsets are conservative) which will alter the geo. You are overthinking it

A wider wheel will create more tension in the sidewall and stop it rolling over on itself under hard cornering. Another data point is the 991 GT3 has a 9 inch wide wheel with a 245 front tire.

Apex Wheels

A lot to touch on here:

• Bump Steer: Any effect that our wider front wheels may have (if any) is so marginal it would likely go unnoticed. Having a passenger in the car is more likely to change the amount of bump steer.
  
• Understeer/Oversteer Balance: With the tire size/model constant, our 9” front wheels should still reduce understeer by increasing the front track width. With that said, the real benefit of our 9” front wheels is the ability to increase the front tire size to 255 or even 265 to meaningfully improve front end grip and to remove unwanted understeer that plagues so many cars from the factory. If you happen to like the balance of the car with the factory tire sizes, then simply enjoy the crisper turn-in 9" front wheels provide due to added sidewall support, as well as the weight reduction.
  
• Steering Feel: This is a real case-by-case basis, but I will explain the best I can. So in relation to a completely stock GT4, our front wheels will change the amount of scrub radius up front which may have a small effect on steering weight but caster will remain the same which is a major part of the steering feel equation. primarily with camber plates but to a lesser extent added LCA shims you are also affecting the scrub radius by screwing with the Kingpin inclination angle (KPA) which is the point from which scrub radius is measured from. What our wheel does for the track day enthusiast who probably runs added camber for both performance and tire longevity reasons is it brings the scrub radius closer (not necessarily all the way) to the factory spec, as well as the wheels being lighter and wider up front. If we take a look at the GT4 Clubsport they run a 18x9" ET41 on the front of those cars which is a full 9mm more aggressive than our 20x9" ET50, and 26mm more aggressive than the factory front wheels. Why would they run such an aggressive wheel spec when compared to the factory street GT4? The Clubsport is intended to be used as a race car from the get-go, so there is no worry about snow tires, NVH, the need for understeer for novice drivers, or anything of the sort. Porsche Motorsport was well aware of roughly how much camber they were going to run the cars with (around -4°) and with what suspension pieces (camber plates and adjustable lower control arms) they were going to use to achieve their goal. So with all that in mind they chose a wheel spec that matches their intentions and provided a scrub radius they were happy with.
  

You can ask any Porsche race shop, the cars that roll off the showroom floor are all compromised for street use and not set up for outright performance. If you want to see Porsche at their best, look at the RSR or 919, these are where you can see Porsche flexing their engineering prowess with all of their attention focused on performance. This is all just a way of saying that just because it's not the same spec as the car came with, that doesn't mean it’s worse. Everything we as enthusiasts do to modify our vehicles is generally for increase performance and much like TRZ06 has done we should question the effects such changes could have on the car as many modifications have trade offs. This just happens to be one such case where there are no real downsides.

- Brandon

Apex Wheels

- Brandon