How long do delivery-robot drive wheels actually last?
Nobody calls us about a drive wheel. They call us because the robot "drifts", "pulls to one side", "stopped docking properly", or "keeps getting lost near the elevator". A good share of the time, the fix is a twenty-dollar polyurethane tread that wore out three months ago.
Why wheels decide navigation accuracy
A wheeled service robot estimates how far it has travelled from wheel rotation. That estimate is only correct if the wheel's effective radius is what the software thinks it is. As the tread wears, the radius shrinks. The robot now travels slightly less than it believes with every rotation, and it accumulates.
On a flat, well-lit floor with plenty of LiDAR features, localisation corrects for this and you never notice. In a long featureless corridor, a service lift lobby, or a warehouse aisle where every rack looks the same, there is nothing to correct against — and that is exactly where people report the robot "getting lost".
Uneven wear between the left and right wheel is worse. The robot believes it is driving straight while it curves, and the correction shows up as a wobble in the path.
What actually wears them
- Floor finish. Sealed concrete and terrazzo are abrasive. Carpet is gentler on tread but loads the motor harder. Polished vinyl is easiest on both.
- Cleaning chemicals. Quaternary disinfectants and high-pH degreasers attack polyurethane. In food service the tread often chemically degrades before it mechanically wears.
- Thresholds and lift sills. Every elevator entry is a small impact. Multi-floor delivery robots take hundreds of those per day.
- Standing still under load. A loaded robot parked for hours in the same spot flat-spots the tread. Flat spots never come back.
- Grit. Fine debris embeds in the tread and turns the wheel into a file that works on both the floor and itself.
The numbers we plan around
| Duty | Typical distance before change | Calendar |
|---|---|---|
| Restaurant serving, single floor | 2,500–4,000 km | 9–18 months |
| Hotel delivery, multi-floor | 2,000–3,500 km | 8–14 months |
| Hospital / senior living, high hours | 1,800–3,000 km | 6–12 months |
| Light-duty office delivery | 3,500–5,000 km | 18–24 months |
These are our own field figures for typical Metro Vancouver installations, not manufacturer ratings. Treat them as a planning range, not a guarantee — the same wheel on terrazzo and on carpet is not the same wheel.
Four signs it is time
- 1. Tread depth under about 4 mm, or the wear indicator (if there is one) is gone.
- 2. A visible flat spot — run your thumb around the circumference, you will feel it before you see it.
- 3. Glazing — the tread looks polished and shiny instead of matte. A glazed wheel slips on ramps and wet floors.
- 4. The robot has started asking to be re-mapped more often than it used to, with no change to the building.
Change the bearings at the same time
The bearing and shaft seal in the drive module live the same hard life as the tread. Replacing them during a wheel change costs about fifteen extra minutes and roughly doubles how long the next wheel lasts, because a dragging bearing puts uneven load into the tread. We do not sell a wheel change without at least inspecting the bearing.
What to keep on the shelf
For a ten-robot fleet, four drive wheels and eight casters on site turns a wheel failure from a service call into a ten-minute job your own maintenance team can do between shifts. That is the whole argument for local stock: the part is cheap, the downtime is not.