The 1998 Toyota Tacoma tire size depends on trim: the Base, 2D Pickup Extra Cab, 2.4 L, Automatic takes P195/75R14 92S; the Base, 2D Pickup Extra Cab, 2.4 L, Standard takes P195/75R14 92S; the Base, 2D Pickup Extra Cab, 2.7 M, Automatic takes P225/75R15 102S; the Base, 2D Pickup Extra Cab, 2.7 M, Standard takes P225/75R15 102S; the Base, 2D Pickup Extra Cab, 3.4 N, 4WD takes P225/75R15 102S; the Base, 2D Pickup Extra Cab, 3.4 N, RWD, Automatic takes P195/75R14 92S; the Base, 2D Pickup Extra Cab, 3.4 N, RWD, Standard takes P195/75R14 92S; the Base, 2D Pickup, 2.4 L, Automatic takes P195/75R14 92S; the Base, 2D Pickup, 2.4 L, Standard takes P195/75R14 92S; the Base, 2D Pickup, 2.7 M, Automatic takes P225/75R15 102S; the Base, 2D Pickup, 2.7 M, Standard takes P225/75R15 102S; the Limited takes P225/75R15 102S; the PreRunner, 2.7 M takes P195/75R14 92S; the PreRunner, 3.4 N takes P195/75R14 92S; the SR5, 2.4 L takes P225/75R15 102S; the SR5, 2.7 M takes P225/75R15 102S; the SR5, 3.4 N takes P225/75R15 102S, per the factory service manual.
Factory-Spec Tire Size
Varies by trim
Base, 2D Pickup Extra Cab, 2.4 L, Automatic: P195/75R14 92S
Base, 2D Pickup Extra Cab, 2.4 L, Standard: P195/75R14 92S
Base, 2D Pickup Extra Cab, 2.7 M, Automatic: P225/75R15 102S
Base, 2D Pickup Extra Cab, 2.7 M, Standard: P225/75R15 102S
Base, 2D Pickup Extra Cab, 3.4 N, 4WD: P225/75R15 102S
Base, 2D Pickup Extra Cab, 3.4 N, RWD, Automatic: P195/75R14 92S
Base, 2D Pickup Extra Cab, 3.4 N, RWD, Standard: P195/75R14 92S
Base, 2D Pickup, 2.4 L, Automatic: P195/75R14 92S
Base, 2D Pickup, 2.4 L, Standard: P195/75R14 92S
Base, 2D Pickup, 2.7 M, Automatic: P225/75R15 102S