Bicycle tyres aren't measured by the diameter, you need to check the size that is written on the side wall of the old tyres before ordering. 
Please feel free to message us with a photo of the old tyres if you are unsure of the size you need. 
Pair or 24x2.125 tyre and tube to suit.

Features:

24x2.125 tyre will also suit (24x2.0 24x1.95 24x1.90 or 24x2.1) 
24inch tube with schrader. please see different types below.