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.