NASA NorCal is excited to open registration for the 20th running of the epic and long-standing endurance race, the NASA 25 Hours of Thunderhill Presented by Hawk Performance. The race runs on a new weekend this year: Nov. 10-12.

The 25 Hours of Thunderhill Presented by Hawk Performance has been reinvented for 2023, with new classing, revised tire rules, scaled pricing by class, and a streamlined registration process. Here are the specifics.



New Classing

EP (formerly ESR) — Open to all prototypes and sports racers.

GT (formerly ES) — Open to any “GT” cars (ST1, ST2, GT3, GT4, stock cars, etc.).

E0 — ST3

E1 — ST4

E2 — ST5

E3 — ST6

New Tire Rules

E0, E1, E2, and E3 vehicles must use treadwear 180 or greater tires. Teams of all classes may change and/or rotate all tires at any legal time. The new rule is designed to lower costs for teams and minimize time spent changing tires.

New Registration Process

New for 2023, the team registers a vehicle, then drivers register themselves for the team vehicle. A minimum of four drivers will be charged per team. If you are registering with fewer than four drivers, please contact Tasha Bigelow at the NorCal office: [email protected].

New Event Pricing

EP/GT team vehicles: $1,395

E0/E1 team vehicles: $795

E2/E3 team vehicles: $395

Driver fee: $450

Crew credentials: $45

We look forward to seeing you at the track November 10-12, 2023! For more information on the rules and pricing, please see the published ruleset.
For assistance or inquiries, please send an email to [email protected].

It is the dawn of a new era for one of the most challenging endurance motor racing events in the nation. This race attracts amateur and professional teams and drivers from around the world to compete in the longest closed-course endurance race in North America.

Image courtesy of Larry Chen [email protected]

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