NASA Announces Super Touring and Time Trial Tire Rules Updates

A combination of member input, new tires on the market, new published and internal testing data has prompted NASA to update the Super Touring and Time Trial rules, to create a new +1.0 modification factor tire category in ST4, ST5, and ST6 classes. Five tire models previously in the +1.4 category are moving to the +1.0 category, effective March 30, 2026.

“We have new tire categories this year for the ST4, 5 and 6 classes,” said Greg Greenbaum, NASA ST and TT National Director. “The -1.0 is new, +0.5 is new, and now +1.0 is also new. We are trying to achieve parity before we get deep into the season and before we get to the Championships, because we would ultimately have to make these changes for next year anyway.”

NASA makes every effort to enact rule changes during the off-season, but the new data shows that these changes are necessary to help maintain parity in the classes, control costs, and give racers the freedom to set their car up as preferences and budget allow.

Previously ST1 through ST4 all used the same modification factor table and the tires were all the same for all those classes. The new rules split the tires so that ST4 cars are now calculated the same as ST5 and ST6 cars.

For ST1, ST2 and ST3, the positive modification factors have been bumped up for the 200 treadwear and slower tires. The change gives competitors the option to try tires that don’t cost as much, but last longer. For example, someone could go from currently using a Hoosier R7 or A7, and instead he or she could try a Maxxis RC-1 and drop from ST2 to ST3.  Yet, these rules allow those that are satisfied with their current setup on Hoosier R7 and A7’s to move to the latest generation R8 and A8’s without making any changes to the car.

For ST4, ST5 and ST6, the new ST1/2/3 tire rules would not have been feasible to allow for choice, because vehicles in these classes would not be able to use the raised modification factors because they are not capable of dropping enough weight or adding enough power physically to achieve the limits of weight/horsepower ratio for the class.

“It’s not just about parity. It’s also giving competitors multiple competitive options using different setups,” Greenbaum said. “We’re also looking to give people options of different setups with less expensive tires or tires that last longer, and still be competitive.”

For specifics for your class, please consult the NASA series rules.