Tire prep is a chemical applied to a race tire to soften or condition the rubber for more grip. Many classes ban tire prep outright and penalize it; whether yours allows it is a rulebook question.
Racers call it prep, soak, dope, softener or conditioner; the aim is always to change what the rubber does, not what the racetrack does. Keep it separate from track prep, which is the water, tilling and packing a crew puts into the racing surface. Legality is purely a rulebook question, and it shifts class to class inside one sanction: IMCA’s 2026 Modified rules allow tires “ground, straight siped or grooved” but state “No chemical softening or conditioning of tires,” while 2026 Hobby Stock gets “No softening, conditioning, siping/grinding or grooving” at all. IMCA’s 2026 general procedures price a chemically treated tire at a “$1,000 fine, 30-day suspension and loss of all points for the season.” Read your own book.
Prep is the fastest way to lose a season — IMCA alone prices a chemically treated tire at a $1,000 fine, a 30-day suspension and every point you have earned.