Technical Discussion

Meet the Stronger, APEX Sprint Spec™ Inner Lip

Article | 11/08/2021 by Brandon Kimbell

One of the most unique features of our Sprint™ Line wheels is the stronger Sprint™ spec inner lip. As avid motorsports enthusiasts, we know that preventing bends in wheels is a huge priority. And as experienced wheel engineers, we know that the inner lip can be a major weak point, especially on lightweight wheels. So when we designed our new Sprint™ Line of lightweight forged wheels, we actually added 32% extra material to the inner lip to increase its rigidity. We didn’t build the lightest wheels we could possibly make, we built the lightest wheels we wanted to make. When you imagine how much lighter our Sprint™ wheels would have been if we had dropped an extra pound by switching to a typical inner lip, you can understand why we’re so proud of what we’ve accomplished with this new line – wheels with a much stronger inner lip that are still extremely lightweight.

You can immediately recognize our Sprint™ spec lip design by the two reinforcement rings that form a strong, C-shaped channel. The combination of the two rings together is much stronger and stiffer than the single, rolled lip found on most wheels, and it saves significantly more weight than if we had made a thick lip without the channel.

In pursuing this stronger lip we experimented with numerous designs. We even laser-scanned and reverse-engineered competitors’ lip designs to ensure we would be releasing something worthwhile and superior. The most common “reinforced lip” designs we saw on other wheels added significant weight while only marginally increasing strength. Our extensive research and experimentation found that the greatest strength increase would come from adding material to an area most other wheels can’t.

To accomplish this, we realized we would need specialized forging dies, so we set out to design new ones from scratch. Dies are the forms used in the production process that compresses the aluminum into basic wheel shapes (blanks) using 10k tons of pressure, similar to stamping a coin.

Our stronger Sprint™ spec inner lip was made possible only by the use of specialized forging dies we spent two years designing.

There’s a reason why you almost never see wheels with a lip design like ours — it’s expensive to make. Most forged wheel companies use raw aluminum blanks that have been designed and manufactured by a 3rd party. Those 3rd parties usually prioritize minimizing the amount of material in a blank to keep unit costs down. And while these blanks are ideal for producing fashion wheels for street use, they force compromises when they’re being used to produce wheels optimized for extreme strength and motorsports. Desirable features such as a specialized inner lip, deeper spoke depth, and greater barrel clearance may be sacrificed, and wheel companies using these 3rd party blanks have to settle for a weaker inner lip profile.

The hard part of getting extra material on the outer corner of the lip is having to add extra material along the entire length of the barrel so it can be rolled all the way out thicker, and then going back and machining off the excess material from the barrel. The specialized blanks we designed let us add material outside the bounds of what almost all other wheels allow. These specialized blanks also give us the ability to offer numerous other features not found on the wheels made from basic 3rd party blanks meant for street wheels. Checkout our article on motorsport dies to learn more about how we were able to create lighter, stiffer wheels, with deeper spokes and better brake clearance, by investing years into designing new dies from scratch.

  • Wheel design: VS-5RS
  • Wheel design: EC-7RS
  • Wheel design: SM-10RS
  • Wheel line: Forged Sprint Line

Brandon Kimbell

Brandon is a Porsche Fitment Expert at APEX Wheels. Prior to joining APEX in 2022, he worked as Office Manager for a Porsche & Ferrari service and race shop, guiding customers in all areas – suspension, power, aesthetics, you-name-it. His first foray into racing came In college when he was asked to assist at a PCA club race. Says Brandon, “I figured if I am already making the drive, I might as well enter the HPDE happening at the same time.” He hasn't stopped since. Among the various cars he has owned and/or tracked are a ‘74 Corvette Convertible, ’74 Firebird Formula 400, ‘17 GTI, ‘07 Cayman S, and his current ride, a ‘12 Cayman R (BGB X51 pack 3.8L) with staggered APEX EC-7RS 18x9”ET46 & 18x10” ET36 in Motorsport Gold. Fun Fact: Brandon is a big fan of SIM racing, which he uses to learn about a new track he’s going to or get a refresher on a familiar track, as well as improve his racecraft.Have questions about wheels for your Porsche? Use our contact form and ask for Brandon.