The most common Pram, Buggy, Pushchair inner tube and tyre size. Motorbike. This tyre and tube set replaces any with the following tyre sizes: 12 x 1.75 or 12 x 1.95 or 12 x 2.00 or 12 x 2.10 or 12 x 2.125 or 12 x 2.20 or 12 x 2.25 or 50-203.