One van down should not cancel the day’s work.
On a large fleet, a unit in the shop is a rounding error. On a 5- to 15-vehicle operation, it can be 10–20% of capacity. That is why small fleets need a spare-vehicle plan — not a pile of old units sitting in the lot “just in case.”
The plan answers three questions: How often are vehicles actually out? What is the cheapest way to cover those days? And who decides when a spare goes out?
Industry rules of thumb often cite a 10–15% spare ratio. On a 10-vehicle fleet, that is one unit. On a 5-vehicle fleet, it is still one unit. The ratio is less useful than your own numbers.
Track these for 60–90 days:
If vehicles are out more than a couple of days a month combined, you need a written coverage option. If they almost never are, a standing rental relationship may be enough.
Internal link: Fewer breakdowns means fewer spare days. See How to Build a Reliable Vehicle Inspection Routine.
| Option | Best when | Watch for |
|---|---|---|
| Shared coverage (another unit absorbs the work) | Short outages, flexible routes, interchangeable vans or pickups | Overloaded remaining vehicles and overtime |
| Short-term rental | Occasional or seasonal gaps, 1–5 days | Availability on short notice and daily cost |
| Dedicated spare | Frequent multi-day outages or specialized setups that rentals cannot match | Insurance, storage, and a vehicle that sits unused |
Most 5- to 15-unit fleets do best with a hybrid: shared coverage for same-day issues, a pre-arranged rental source for 1–3 day gaps, and a dedicated spare only if the math supports it.
Run a simple yearly comparison.
Cost of owning a spare
Cost of not having one
If rental days already approach the annual cost of a basic van or pickup, a dedicated spare can be the cheaper, more reliable option. If rentals are rare, keep the relationship and skip the extra unit.
Do not keep an old vehicle “because it is paid off.” An unreliable spare creates a second problem the day you need it.
Write four rules and post them:
Without rules, the spare becomes someone’s daily vehicle, and you are back to zero coverage.
Internal link: Pair this with a clear first-response process. See Creating an Emergency Breakdown Plan.
If rentals are part of the plan, set them up in advance:
A rental that takes four hours to arrange won't cover a morning breakdown.
Tell your insurer if you add a spare or start using rentals regularly. A vehicle that sits still still needs coverage. Confirm rental coverage before the first use so a claim isn't a surprise.
Log every spare or rental day: which primary unit was down, why, and how long. After 90 days, the log shows whether the plan is working or whether you need one more unit — or fewer.
External resource: For vehicle safety and commercial operating basics, the Federal Motor Carrier Safety Administration remains a solid official reference.
A spare plan is not about having extra vehicles. It is about keeping the same work moving when one unit is out.
Need help deciding whether a spare fits your current vans and pickups? Contact Wilmar. We can review how your units are used, compare coverage options, and structure a lease so downtime doesn't stop the day’s work.
How many days a month is at least one vehicle out right now? Share it in the comments or reach out directly.
Further Reading:
Q: How many spares does a 10-vehicle fleet need?
A: Often one, if vehicles are interchangeable and downtime is moderate. Start with your own out-of-service days. A percentage alone does not decide it.
Q: Is an old paid-off van a good spare?
A: Only if it starts reliably and can do the work. An unreliable spare fails the day you need it and still costs insurance and space.
Q: When is a rental better than owning a spare?
A: When coverage days are occasional. If you only need a vehicle a few times a year, a pre-arranged rental is usually cheaper than a year-round payment and insurance.
Q: Can drivers use the spare for regular routes?
A: No. Once the spare becomes a daily vehicle, you no longer have coverage. Write the rule and enforce it.
Q: Do we need a spare if we already have a breakdown plan?
A: The breakdown plan gets the driver safe and the unit towed. The spare plan keeps the job moving while that unit is out. You need both.
Q: Should the spare match our other vehicles?
A: As closely as practical. A spare that cannot carry the same load or tools does not actually cover the work.
Q: How often should we review the plan?
A: Every quarter. If rental days or downtime keep rising, it is