Among a few changes coming for the 2026 NTT IndyCar Series season, a new rule will be in place regarding the use of Firestone’s alternate tires.
Alternate tires are made of a softer compound of rubber than primary tires, and give drivers and teams additional strategy options for the race weekend.
The softer compound is available on all road and street courses throughout the season, and is denoted by a red or green stripe on the outer sidewall.
In recent years, each entry has been required to use at least one set of new alternate tires during each race where they are available.
Beginning this year, that rule has been modified to require that two sets have to be used during every street course race.
The previous requirement for the tires to be new, as opposed to a lightly used or scrubbed set, has been removed.
“IndyCar is always looking into ways to improve the quality of what is already exceptional on-track action,” IndyCar Senior Vice President, Competition and Operations Mark Sibla said.
“This street circuit update will challenge drivers and strategists alike and provide an avenue for even more memorable wheel-to-wheel action at our fan-favored street events in 2026.”
Each tire set will be considered to have satisfied the rules if it fitted to the car for two complete laps, one of which must be under green.
The updated rule will force drivers to race more laps on the compound that degrades more quickly, potentially adding a level of variance to strategies chosen up and down pit lane.
Only a single set of alternate tires will be required for permanent road courses, continuing from the previous ruleset.
The new rules begin this weekend in St. Petersburg, for the first of six planned street course races on the 2026 calendar.