Tyre manufacturers print the size on the sidewalls, so look out for numbers such as '700x23c' for a road bike, or '26x1.75' which is for mountain bikes.
Abakhiqizi beTire baphrinta usayizi ezindongeni eziseceleni, ngakho-ke qaphela izinombolo ezifana ne-'700x23c 'yeukuumgwaqoibhayisikili, noma u-'26x1.