Exmark 120-5515 Caster Wheel Quest E S Series

What It Is

The Exmark 120-5515 is a genuine OEM caster wheel assembly designed for Exmark Quest E and S Series zero-turn mowers. It replaces the front swivel wheel to restore smooth steering and stable deck height on residential/commercial turf.

Fitment & Compatibility

This wheel fits Exmark Quest E Series (model years 2016–current) and Quest S Series (2018–current). Do not assume it fits older Quest models or other Exmark lines (Lazer, Radius).

• Deck size: Works with 42", 48", 50", 52", and 60" decks on compatible Quest models.
• OEM vs aftermarket: This is a genuine Exmark part, not a generic replacement. Aftermarket alternatives may differ in bearing quality and tread compound.
• Measurement check: The wheel is 11" diameter with a 5/8" axle hole. Verify your existing caster’s bolt pattern and stem length (1.5" typical) match.
• Model verification: Look for “Quest E” or “Quest S” on your mower’s serial tag (under seat or on frame). Cross-reference your model number with Exmark’s parts list.

Key Things to Know

• Quality: Heavy-duty steel rim with sealed ball bearings and a non-marking tire. Expect longer life than standard plastic-hub casters.
• Installation difficulty: Easy—requires removing a single cotter pin and washer. No special tools beyond a socket or pliers.
• Common gotcha: The tire is pre-inflated; do not overinflate or attempt to add air (it’s foam-filled on some batches). Check that the swivel bracket isn’t bent before installing.
• Fitment nuance: If your mower has a “Quick Attach” deck system, ensure the caster stem is the correct length (1.5” vs. 2” on older models). Measure your old stem to be safe.

Should You Buy It

If you own a Quest E or S Series and need a direct, trouble-free caster replacement—especially after a blown bearing or worn tire—this is the right part. It’s pricier than aftermarket options but saves hassle with guaranteed fit and OEM durability. Not for other Exmark models or generic mowers.