A caster’s swivel lead is the measured distance from the vertical centerline of the swivel section to the vertical centerline of the wheel.

And once you know the swivel lead, it’s easy to calculate the swivel radius.

There are a couple of reasons why it's important to know a caster’s swivel radius:

• In general, the longer the swivel radius, the easier the caster will rotate.
• A caster’s swivel radius lets us know the minimum clearance that’s required for a mounted caster to swivel 360 degrees.

Note: It’s crucial that no obstructions exist within a caster’s swivel radius.

Another note: Sometimes brakes (or caster options like toe guards) can project past the outer edge of the wheel and extend the swivel radius.