ZENITH RACING SERIES - BARBER [ROUND 2, Race] TIRE TEST REVIEW

May 06, 2026

Coming off another strong race weekend, we have additional sets of real race data to work from. Similar to previous events, the #95 BMW M4 GT4 driven by Matt Million and Colin Garrett collected a range of data for several different tire strategies to further refine out tire lap deduction ruleset. The event gave us meaningful tire runs across all three options, including multiple Yokohama A052 references, a Pirelli slick stint, and a Continental ExtremeContact Force.

The goal of the proposed rule is to keep the tire choice open. A team should be able to chase pace, chase durability, or land somewhere in the middle. The lap deduction needs to make each option carry the right cost so that the fastest tire is not automatically the best answer.

DATA USED

The No. 95 BMW ran the Yokohama A052 in Saturday’s race. It then started Sunday’s race on the Pirelli slick before switching to the Continental ExtremeContact Force for the remainder of the race.

Additional Yokohama A052 data came from the No. 290 MoreHead Speedworks Ginetta G56, driven by Ari Balogh and Jerry Kaufman.

For the data collected, major outlier laps were removed so pit laps, tire-change laps, and abnormal laps did not distort the average. The filter removed laps more than 115% of the fastest lap in that tire sample. Race data can be found on the Zenith Racing Series competitor page. Click Alkamel Scoring Noticeboard and navigate to the desired session reports.

WHAT CHANGED FROM BARBER TEST IN FEBRUARY?

In February, the series performed a standalone tire test to help collect data for the event in addition to the live race data being collected at events. The standalone Barber test in February did not show degradation nearly as clearly as the race weekend did.

Coming out of the February test, the gap between average lap times between the tire options looked smaller. The race weekend created a more demanding picture. Over real stint conditions, the Pirelli held a much stronger average pace than expected, while the Yokohama and Continental showed more degradation from the slick than the early test suggested.

The Pirelli was not only quick on peak lap time. Its usable average pace over the stint was strong enough that a meaningful tire-use penalty is required.

AVERAGE PACE FOUND [IN DATA]

The Pirelli slick sample from the No. 95 BMW averaged 1:32.190 over 67 clean laps, with a clean run time of 1:42:56.745.

The Yokohama A052 sample from the No. 95 BMW on Saturday averaged 1:35.644 over 109 laps, equal to 2:53:45.196 of running time.

The Yokohama A052 reference from the No. 290 MoreHead Speedworks Ginetta averaged 1:35.425 over 99 clean laps, with a clean run time of 2:37:27.084. That number being within roughly two tenths of the BMW Yokohama sample gives us more confidence in the A052 range.

The Continental ExtremeContact Force sample from the No. 95 BMW averaged 1:37.450 over 106 clean laps, with a clean run time of 2:52:09.733.

7-HOUR RACE ASSUMPTIONS

For understanding how this would affect our standard 7 hour race format, we can extrapolate this out to 25,200 seconds divided by the average lap time in seconds.

Using those averages, the Pirelli projects to 273.35 laps over seven hours. The BMW Yokohama sample projects to 263.48 laps, while the Ginetta Yokohama reference projects to 264.08 laps. The Continental projects to 258.59 laps.

That puts the Pirelli at roughly 14.76 laps better than the Continental before any tire deduction. The BMW Yokohama sample is roughly 4.89 laps better than the Continental, and the Ginetta Yokohama reference is roughly 5.49 laps better.

Based on the data from Barber, we believe the Pirelli slick can run a maximum of 2 hours and 20 minutes, which means it needs three sets, or 12 tires, to complete the race.

The Yokohama A052 can run approximately 3 hours and 30 minutes, which means it needs two sets, or 8 tires.

The Continental ExtremeContact Force can complete the race on one set, or 4 tires.

TIRE CHANGE LAP DEDUCTION FOR 7+ HOUR RACES
(for 12H+ Races, please review the event supplemental regulations for deduction rule)

The updated regulation is based only on total tires used.

·      Tires 1 through 5 carry no lap deduction.

·      Tires 6 through 8 carry a 1-lap deduction per tire.

·      Tire 9 and every tire after that carries a 2-lap deduction per tire.

Under the expected strategy, the Continental uses 4 tires and receives no deduction. The Yokohama uses 8 tires and receives a 3-lap deduction. The Pirelli uses 12 tires and receives an 11-lap deduction. Pit stop time loss for the tire changes is also considered in the adjusted laps.

·      The Pirelli moves from 273.35 projected laps to 261.50 adjusted laps.

·      The Yokohama BMW sample moves from 263.48 projected laps to 260.27 adjusted laps.

·      The Continental remains at 258.59 projected laps.

The Pirelli still has an advantage over the Yokohama, and the Yokohama still has an advantage over the Continental, but both gaps are compressed significantly. That is the intended shape of the rule. The faster tire can still be better if everything works, but the team has to accept more tire usage, more timing risk, and more exposure to pit-lane loss.

CONSIDERATIONS: CODE 60 TIMING MATTERS

The remaining advantage for the faster tires assumes a very favorable race shape.

If the Pirelli or Yokohama strategy gets a Code 60 at the exact point where the tire has reached the end of its useful life, the team can change tires with minimal loss. For this model, that Code 60 tire-change loss is estimated at roughly 20 seconds per stop.

If the Code 60 does not arrive at the right time, the team either stays out on a tire that is past its best window or makes a green-flag tire stop. In that case, the tire-change loss can move from about 20 seconds to closer to 60 seconds per stop.

CONSIDERATIONS: MISSED-WINDOW SCENARIO

The missed-window case is where the tire-count rule starts to matter most.

If the Yokohama strategy misses the right window and needs an extra tire, it moves from 8 tires to 9 tires used. The lap deduction increases from 3 laps to 5 laps. Before adding any extra pit-lane time, the Yokohama projection falls from 260.27 adjusted laps to 258.27 adjusted laps.

The Pirelli missed-window case works the same way. If the Pirelli strategy needs two extra tires, it moves from 12 tires to 14 tires. The lap deduction increases from 11 laps to 15 laps. The Pirelli projection drops from 261.50 adjusted laps to 257.50 adjusted laps.

That is why the faster tire options can show a small advantage in the ideal model without being unchecked in the actual race. If the timing is wrong, the penalty escalates quickly. Extra tires add laps to the deduction, and extra stops add real time loss.

PRACTICAL RESULT

The Continental is the lowest-risk strategy. It is the slowest average lap, but it avoids tire-change timing risk and carries no deduction.

The Yokohama is the middle option. It is meaningfully faster than the Continental and needs only one planned tire change, but the expected 8-tire strategy carries a 3-lap deduction. If it needs extra tires, the penalty jumps quickly.

The Pirelli is the high-upside option. It has the strongest average pace, and the race weekend data showed a larger advantage than the February Barber test suggested. It also requires the most tires. Under the expected 12-tire strategy, it receives an 11-lap deduction. If the team misses the window and needs extra tires, the strategy can fall back toward or even behind the Continental projection.

That structure keeps the tire choice alive. Teams can still pick peak pace, middle-ground pace, or full-race durability. The rule simply makes sure the faster strategy carries enough cost and risk to keep the race from becoming a single-compound answer.