Factory OEM Porsche Aluminum Wheel:
First up was the OEM Porsche wheels. After doing a sighting lap in another car to ensure track conditions were good, we re-checked the cold pressures and I buckled myself in the car and did two nice, easy out-laps to scrub the mold release agent off of the tires. As expected, the front tires took a bit of sawing at the wheel to get them to come in but as soon as they were cleaned off, the front of the car switched-on and we were good to start our first flying lap.
As expected from the Trofeo-Rs, the first flying lap was the fastest, but as the lap times wore on, so did the left-front tire on this primarily right-hand track. Turns 8 & 9 are a long, double-apex right-hander that requires a lot of entry speed and trail-braking to make it far into the corner before rotating the car and powering out of. Even with a very late-apex, Turn 9 is so long that you can’t escape from the Porsche’s typical on-throttle understeer, which wore away at the LF tire.
Adjusting the line with a longer trail-brake to further reduce understeer in turn 8 helped to put down a good time half way though the run, but there was no escaping the excess wear on the LF that quickly felt worse and worse as if you’re dragging the tire across a cheese grater.
After the 10 laps we came in for a quick tire and wheel change.
Carbon Revolution CR-9 Wheel:
Once the CR-9 wheels were mounted and after double checking the tire pressures, I headed back out on track. Once I left pit lane, the difference in the carbon wheels caught me by surprise. Just making the slow left turn leaving the pits (not cornering any harder than you would on the street), the response from the car and how quickly it ‘pointed’ in to the corner and how connected the steering was apparent when I was not even considering paying attention until the start of the first timed lap.
Sure enough, by the time I made my second turn in the long Turn 2 sweeper, the improved steering response and direct feel remained consistent, backing up what I just felt in the previous turn and responding very quickly even on cold Trofeo R’s! The difference was so apparent that it felt like I was on completely different tires, as if the baseline was done on soft sidewall all-season tires, and I was now on R-compounds. It really was that noticeable and I wouldn’t believe it if you told me.
During the 2 laps of scrubbing in the front tires, the steering felt more direct and connected to the tire. I don’t want to say the steering was necessarily lighter, since I don’t like overly light steering, but the steering response felt cleaner and more exact in the way a Lotus Elise/Exige or original NSX with no power steering gives you that feeling through the steering wheel of being directly connected to the road, the carbon wheels gave this Porsche that same character. It is eye-opening to see how this ‘enabling-technology’ really did help the steering feel of the Ford GT, which already has hydraulic steering and one of the coolest suspensions of any road car, but especially the GT350R that’s still mechanically (steering wise) a Mustang.
After the front tires switched-on, I was ready for my 10-lap timed run. Lap 1 was a good 0.38 seconds faster than the old baseline and what really suck out was how sharp turn-in was. I could be smoother and slower with my hands to get the same chassis reaction out of the car, meanwhile I didn’t need as much steering input to get the car to turn. Another thing that greatly stuck out was the improved front grip, especially when trail-braking. Trail-braking is the hardest load on an outside front wheel because it’s both braking and turning. If the wheel is going to flex, trail-braking is when it will flex the most.
Sure enough, the stiffer carbon wheel had more front grip in trail-braking, allowing me to brake even later, carry more entry-speed and getting the car rotated sooner before putting the power down. Putting the power down was also immediately more responsive.
The curbs are not necessary to use at LVMS but I picked a few to hit consistently on all the laps just to see how the wheels react over bumps since otherwise, the track was billiard-table smooth. The carbon wheels soaked up bumps without launching off the curbs like it did with the aluminum wheels. The car landed with a single hop recovery, while the aluminum wheels had two undulations of recovery.
Overall, the improved response of the car made it feel like I was on a more aggressive, stickier tire. Or as if either the car had stiffer sway bars or suspension bushings. The difference was quite noticeable and you don’t have to be a racecar driver to feel it. I’m sure pretty much anyone who enjoys driving would be able to tell a difference.
As the laps clicked off, the Carbon Revolution wheels were consistently faster and more importantly, consistent than the baseline run. Where the front tires were all but gone by the end of the 10-lap run on the baseline, I had plenty of front grip and probably should have pushed the LF tire harder in the long sweeping right-handers.
It was quite eye-opening to experience such an improvement in the steering feel, front grip, and nimbleness of the car. I was very interested in seeing how the left-front tire held up. Once I got back to the pits, I hopped out of the car and immediately looked at the LF tire. I was blown away to not see any of the blistering like we saw on the OEM aluminum wheel.
Now Porsche is a great company and they know how to make a lightweight wheel. They also know how to make a strong wheel. These OEM aluminum wheels cost well over $5K and are excellent, especially compared to most aftermarket wheels. However, there was an obvious and visual amount of camber compliance going on here. With no other difference than the wheels, for the tire to roll-over and blister like it did, the wheel had to deflect and lose dynamic camber, which focused the heat on the outer-edge of the tire and punishing it beyond its operating range to fail and blister.
By comparison, the Carbon Revolution wheel is much stiffer, has far less camber compliance and thus, effectively has more camber mid-corner to spread the load across the tire more evenly. This allowed the tire to work better and explains our increased front grip. Remember, the only change was the wheel. We were on the same size wheels and tires and started with the same cold pressures and ran within minutes of each other. A comparison test doesn’t get much better than that.
Carbon Revolution themselves were quite surprised as well and didn’t expect to see such an obvious and empirical evidence of the difference of camber compliance. But it makes sense that having such little static camber (factory camber is around -0.5* in the front) on a very sticky and aggressive tire would be a great method to show camber compliance. If the car had more static camber, the only way we could have shown camber compliance is by looking at tire temperatures with a probe-type pyrometer.
This visit to Las Vegas Motor Speedway was quite eye-opening. We learned a lot regarding the importance wheels play on the performance of the car and how stiffness, light weight, lower rotational inertia, and unsprung mass improve steering feel, tire wear, grip, and lap time.
We walked away with real-world visual tire wear evidence of the increased stiffness Carbon Revolution wheels have over high-end OEM aluminum wheels. We also gathered data that showed a lap time improvement of 0.38 seconds on a 50-second lap, which would translate to close to a second on most tracks with 2-minute laps.
Carbon Revolution has shown us the future of wheels and how the use of carbon fiber technology can improve every aspect of how a car rides, performs, and ‘enables’ every aspect of the car to work better. Carbon truly is a revolutionary material that shifts the paradigm of what wheels can do the same way carbon fiber monocoques changed the face of aircraft and racing.
Going back to the original question: Do your wheels flex? -Of course they do, they all do. But depending on the material, design, and weight of your wheels, it may be a little or significant. When buying a new set of wheels, be sure to consider not only the brand and quality of the wheel, but the trade-off between stiffness and weight. The only way to have a significant amount of both is to go to a game-changing carbon fiber wheel, which has countless performance and ride benefits above and beyond simply bragging rights and bling factor.
Table of Contents:
Page 1 – Intro
Page 2 – Carbon Fiber Wheels used by OEMs
Page 3 – Benefits of Carbon: Lightweight – Rotational Inertia
Page 4 – Benefits of Carbon: Lightweight – Gyroscopic Effect
Page 5 – Benefits of Carbon: Strength
Page 6 – Benefits of Carbon: Stiffness
Page 7 – Benefits of Carbon: Stiffness Continued – Camber Compliance* (Must-Read)
Page 8 – Benefits of Carbon: Durability, NVH & Cost.
Page 9– Important Factors for wheels on Racecars & Track Test Procedure
Page 10 – Wheel Weights, On-Track Testing, Data/Laptime/Tire Analysis, and Conclusion