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ISO Sizes for Bicycle Tires and Rims

Think all 26" tires are the same size? They aren't. There are actually three different 26" tire sizes. To get the correct size tire, don't rely on the common size - use the ISO measurement from the tire or measure your rim.

What is the ISO size? It's the diameter of the bead of the rim in millimeters and should match precisely to the rim.

Bicycle Tire Size Markings

Bicycle Tire Size Markings

Bicycle Rim Sizing

Bicycle Rim Sizing

Common Bicycle Tire Sizes and ISO Measurements

Common Name

ISO in MM

ISO In Inches

12.5"2038"ISO 203 Tires
14"25410"ISO 254 Tires
16" BMX / Kids30512"ISO 305 Tires
16" Recumbent34913.75"ISO 349 Tires
18" BMX / Kids35514"ISO 355 Tires
18"40015.75"ISO 400 Tires
20" BMX / Kids40616"ISO 406 Tires
20 x 1-3/4"41916.5"ISO 419 Tires
20 x 1-3/8", 20 x 1-1/8"45117.75"ISO 451 Tires
22"45718"ISO 457 Tires
22" Wheel Chair50119.75"ISO 501 Tires
24" BMX / Kids50720"ISO 507 Tires
24" Old Schwinn S-7 Size52120.5"ISO 521 Tires
24" Wheel Chair54021.25"ISO 540 Tires
24" Old Schwinn S-5 Size54721.5"ISO 547 Tires
26" Mountain55922"ISO 559 Tires
650c - Small Road Bike57122.5"ISO 571 Tires
27.5 / 650b58423"ISO 584 Tires
26 x 1-3/859023.25"ISO 590 Tires
26" Old Schwinn S-659723.5"ISO 597 Tires
700c, 29", 28"62224.5"ISO 622 Tires
27" Road63024.8"ISO 630 Tires
36" Big Bike78731"