2026 NASA TT Rules: What Changed and Why It Matters

The 2026 rulebook (TT Rules v23.1, with ST companion updates through v20.2) makes three changes that actually affect how you'll class, build, and enter. Here's what moved and what to do about it.

1. TT Street: the street car finally gets its own scoreboard

New for 2026, TT Street is an overlay, not a class: register in your normal TT class, and if the car wears 200+ treadwear tires and holds current street registration, you're also scored in the Street standings. No extra fee structure, no separate run group.

Why it matters: the daily-driven GT car or hot hatch that used to finish mid-pack behind trailered, gutted builds now has a competition it can win without touching the car. If you drive to the track, you're likely already eligible — check your class assignment in the TT Engineer tool and you're done. This is the single best on-ramp change NASA has made to TT in years, and it directly attacks the "I can't compete with trailer cars" objection covered in our cost breakdown.

2. Tire reclassification: five tires drop to a new +1.0 factor (effective March 30, 2026)

NASA created a new +1.0 tire category in the TT4/TT5/TT6 factor tables (mirroring ST4/5/6), moving five models down from the +1.4 group — the RE71RS/A052/CR-S/RCES tier now carries +1.0, with a new +0.5 tier (RE71RZ, Supercar 3R, Vitour P-01R) and a −1.0 slot for the Hoosier R8 rounding out the ladder. Per ST/TT National Director Greg Greenbaum, the goal is parity, cost control, and setup freedom as new tires hit the market.

Why it matters: if you run TT4–TT6, your adjusted ratio may have changed mid-season without you touching the car. A tire that was +1.4 in March may be +1.0 now — that's 0.4 of ratio, which near a class floor is the difference between legal and bumped. Re-run your classing math before your next event, and re-file the form if your number moved. It also quietly reprices the used-tire market: the +1.0 group is now the value play in the lower classes.

3. TTT (Time Trial Target): everyone is in a second competition

TTT scores consistency rather than raw pace, and every TT entrant is automatically included. There's nothing to sign up for and no way to opt out; there's simply a second leaderboard where hitting your target times beats being fastest.

Why it matters: for new competitors, TTT makes weekend one competitive — repeatability is a rookie-accessible skill in a way that outright pace isn't. For veterans, it's contingency-relevant hardware for driving you were doing anyway. Full class context in TT Classes Explained.

Unchanged but still ambushing people

Two rules that didn't change in 2026 but keep catching entrants: active aero remains illegal in TT1–TT6 (992 GT3 RS DRS included — disable and fix it, or run TTGT/TTU), and dyno-on-demand with GPS power monitoring remains in force, so declared horsepower still needs honest headroom.

Rules current as of July 2026 (TT v23.1). This page is reviewed quarterly; the complete getting-started guide is always the current-season reference.