Slick vs. 200TW Compounds: Barber Motorsports Park Follow-Up Test

Following our initial tire testing at NCM Motorsports Park, we headed to Barber Motorsports Park with the goal of learning more about the peak performance delta between the Pirelli Slick compound tires, Yokohama A052, and Continental ExtremeContact Force.

At NCM, the focus was long-run degradation and understanding how different compounds behave within a Code-60 race format. Barber allowed us to shift our focus to answer three primary questions:

• What is the peak performance delta of the Pirelli slick relative to the Yokohama A052?

• Does the Yokohama still show a strong peak performance delta over the Continental?

• Do the percentage gaps scale proportionally at a very different circuit?

Barber presents a completely different challenge compared to NCM. It is shorter, more technical, and places different loading characteristics on the tire. If the percentage gaps remained consistent, that would give us greater confidence that our original findings were not track-specific.

Compound Philosophy

While we reference specific brands in this report, our intent is not to advocate for one tire over another. For modeling purposes, these compounds represent three general tiers:

• A soft compound expected to last approximately two hours

• A medium compound expected to last approximately four hours

• A hard compound expected to last seven-plus hours

Exact suitability can vary based on conditions, but the purpose of this testing is to understand how these tiers interact competitively. Longevity validation will occur at Sonoma during live race conditions.

Peak Performance Findings at Barber

Most laps during the session contained minor traffic, so we are referencing both fast lap and theoretical lap data to represent clean performance potential.

Pirelli Slick- Fast Lap: 1:31.00; Theoretical: 1:30.48

Yokohama A052- Fast Lap: 1:32.00; Theoretical: 1:31.63

Continental ExtremeContact Force- Fast Lap: 1:33.48; Theoretical: 1:33.15

Using theoretical laps for consistency:

• Yokohama is 1.15 seconds (1.27%) slower than the Pirelli slick

• Continental is 2.67 seconds (2.95%) slower than the Pirelli slick

• Continental is 1.52 seconds (1.66%) slower than the Yokohama

Cross-Track Validation

At NCM, the Continental was 1.63% slower than the Yokohama on peak performance. At Barber, that number measured marginally higher at 1.66%. Despite very different layouts, surfaces, and load profiles, the percentage gap remained nearly identical. This consistency is important as it suggests that the incremental performance spacing between compounds is not isolated to one specific circuit.

One-Lap Deduction Scaling

Because our penalty structure is lap-based rather than time-based, it naturally scales with track length. For example, a one-lap deduction at Barber represents fewer raw seconds than at NCM (92 seconds vs. 132 seconds). Although the per-lap performance gain is proportionally smaller at Barber, the overall gain of the softer compound tires nearly identical to that of a longer circuit like NCM.

Since the penalty scales with length of the track, but the performance gain seems to remain constant, a shorter track like Barber presents an opportunity where the softer compound tire becomes the more advantageous strategy (a swing of the delta between lap times which is about 40 seconds). The frame work, while still hypothetical, remains in a window where either the soft compound strategy and hard compound strategy are within roughly 30 seconds of each other over the course of 7 hours. However, we do plan to put many of these degradation theories to the test in a full simulated race environment at Sonoma.

Strategy Diversity at Sonoma

One of the most encouraging aspects of this discussion has been how different competitors’ opinions on the subject are. We have received feedback from requiring a spec compound that is guaranteed to last the entire 7 hours to completely removing the tire change rule and allowing teams to change tires freely. For Sonoma, our current confirmed ZR2 competitors will be competing on the following compounds:

• Hankook RS4

• Continental ExtremeContact Force

• Hoosier Track Attack Pro

• Bridgestone RE-71RS

• Yokohama A052

This variety speaks to the fact that competitors are exploring multiple approaches that suit their team’s best interest (driver fun factor, budget, performance, etc.). We believe it is our responsibility as a series to balance these options, not limit them.

What Comes Next

Barber provided peak performance validation. Sonoma will provide an opportunity to validate the degradation characteristics of compounds. At Sonoma, we intend to collect real data from our 3 tiered compounds in extended running environments.

Our goal is to observe how these tires perform over continuous race environments within our format, not just during test sessions. Only after gathering that data will we further understand how peak percentage deltas and real-world degradation interact. We will share those findings openly.

Be sure to tune into our first event via live timing and scoring through Alkamel’s live timing website: https://livetiming.alkamelsystems.com/usac and through our live broadcast via the Zenith Racing Series YouTube channel. Thank you all for the amazing response. We’re very thankful to have such a passionate following from the community, especially before we’ve hosted our first event as a series. We can’t wait to showcase what we hope to be an amazing platform for you all to compete, race hard, and ultimately have fun!

Pirelli Slick (Red) vs. Conti (Black)