How to Change Office Chair Castors

Castors are the easiest part of an office chair to replace yourself. On most chairs you need no tools, it takes about five minutes, and the right wheels stop a chair scratching a wooden floor or dragging on carpet. This guide is written for Herman Miller chairs such as the Aeron, Mirra, Sayl and Embody, but the same method works on most office chairs.

Signs your castors need replacing

• The chair drags, judders or pulls to one side when you move.
• A wheel has stopped turning or has worn a flat spot.
• Scratches or marks are appearing on a wooden, laminate or vinyl floor.
• The chair squeaks or clicks as it rolls.
• Hair and fluff are wound so tightly round the axles that cleaning no longer helps.
• A castor drops out when you lift the chair.

Which castors for which floor

The names catch a lot of people out. Castors are named after the floor they are made for, not after the wheel itself.

Hard floor castors are for wood, laminate, tile, vinyl and other hard surfaces. The wheel has a softer outer tread, so it grips the floor, rolls quietly and is far less likely to scratch.

Soft floor castors are for carpet. The wheels are hard nylon all the way through, so they roll freely over carpet pile. On a hard floor they can skid, and over time they can mark the surface.

Rollerblade wheels are larger 3-inch wheels in the style of inline skate wheels. They roll smoothly and quietly on hard floors and also cope with carpet. Because they are bigger than a standard castor, the seat sits a little higher, so check your seat height once they are fitted.

Protecting a hardwood floor

If your chair is on wood or laminate, fit hard floor castors or rollerblade wheels rather than hard nylon ones. Keep the wheels clean as well: most scratches come from grit trapped in the tread, not from the wheel itself. If you would rather not change the wheels, a chair mat is the other option.

Will they fit my chair?

Herman Miller chairs, including the Aeron (Classic and Remastered), Mirra, Sayl, Embody, Setu and Celle, use the standard castor stem found on most office chairs: a push-in stem about 11mm across and 22mm long, held by a spring ring. You may also see this size written as 7/16 inch. All three of our castor sets use this fitting.

For any other chair, pull one castor out and measure the stem. If it is about 11mm across and 22mm long, these castors will fit. Some chairs use a screw-in (threaded) stem instead, which these will not fit.

How to change office chair castors

You will need the new castors and, for a stubborn one, a flat-head screwdriver or a pair of pliers. Allow about five minutes.

1. Lower the chair and turn it over. Put the seat at its lowest height, then lay the chair on its side or turn it upside down on a rug or towel so you can reach the base easily.
2. Pull the old castor straight out. Grip the wheel housing and pull firmly away from the base. The stem is held by a spring ring, so it needs a sharp pull rather than twisting. If it will not move, slide a flat-head screwdriver between the castor and the base and lever gently, working round the stem.
3. Clean the socket. Wipe any dust or hair out of the hole in the base leg.
4. Push the new castor in. Line the stem up with the hole and press it in until you feel it click past the ring. If it is tight, start all five, stand the chair upright and press down firmly on the seat. Your weight will push them fully home.
5. Check every wheel. Roll the chair around, make sure every wheel turns freely, and lift the chair to check none drops out.

Change all five castors at the same time, so the chair rolls evenly.

Keeping castors rolling

Every few months, turn the chair over and pull any hair or thread off the axles. A pair of tweezers makes this much easier. Wipe the wheels with a damp cloth to remove grit, especially if the chair is on a wooden floor.

Doing a bigger refresh?

If your Aeron needs more than new wheels, the Aeron refurbish kit includes castors along with a lumbar support, arm pads and seat foam. For a sinking seat, see how to change the gas lift on an Aeron.

Not sure which castors your chair needs? Email us a photo of your chair and floor, and we will tell you.