Wheel size varies by bike type. (Common Widths: 700c, 29”, 28”, 27.5”, 26”, 24" and 20")
Road bikes and urban bikes with narrower tires are normally called 700c and Mountain bikes are called 29" (29er) or 27.5" or 26". Often, this is noted on your tire’s sidewall. Sometimes you will see one set of sizing numbers on a tire, or two or event three. As long as your tire numbers match our fender guide you will buy the right fender.
A tire size you might see on a mountain bike:
29 x 2.35 indicates a tire with a 29" wheel size and a 2.35" tire width.
A tire size you might see on a road bike:
700x25c indicates a tire with a 700mm wheel size and a 25mm width.
The tire width is just to the right of the wheel size.
The size and width is normally imprinted or embossed on the side wall of the tire
Typical tire widths:
The example sizes below give you a rough guide for tire sizes on different types of bikes today.
Mountain bike tires:
Wheel sizes can be 26", 27.5" or 29"; widths range from 1.9" to nearly 5" tire widths.
Some examples:
Cross-country bikes: 1.9" to 2.3" wide.
Trail and all-mountain bikes: 2.3" to 2.5" wide.
Downhill bikes: up to 2.5" wide. Gravel bikes: Most gravel bikes typically use a 700c wheel size and tire widths ranging from 35-45mm.
Urban/Road bike tires: Most road bikes have a 700c wheel size, with widths starting at 23mm. Most road tire widths range from 25-40mm.
Kids’ bike tires: Typical diameters are 20" and 24", though you also see wheel sizes below 20" for very small children’s models; widths vary widely as well.