CB350 Front & Rear: 18" x 3.25" - 4" Inner Tubes
SL350 / CL350 Rear only: 18" x 3.25" - 4" Inner Tubes
SL350 K0 / SL350 K1 / CL350 Front only: 19" x 3.25" - 4" Inner Tubes
SL350 K2 Front only: 21" x 3.25" - 4" Inner Tubes
http://www.common-motor.com/honda-inner-tube