Guides
Tire tread stock counts: how to set reorder points that survive the rush
A per-size method for setting tire tread stock reorder points and safety stock, with lead time math, a worked example and a winter rush buffer.
What to take away
- A tire tread stock reorder point is lead time demand plus safety stock, set for each size on the rack.
- Lead time demand is average daily units sold multiplied by the supplier lead time in days.
- Safety stock comes from peak daily units, not the yearly average.
- Review the points before the September and March buying windows, and after any supplier change.
- Turn unit counts into dollars with your tire shop cash flow basics, so the shelf figure and the bank balance agree.
Why one minimum stock level fails
Most shops keep four of everything and hope. The rule breaks in both directions. Slow sizes hold cash for months. Fast sizes sell out on the busiest Saturday of the fall.
Demand, lead time and cost differ by size, so a shared number cannot serve them all. A 205/55R16 and a 275/60R20 share almost nothing except rubber.
The formula: lead time demand plus safety stock
Work one size at a time, from point of sale data rather than memory.
The formula
- Lead time demand equals average daily units sold for that size multiplied by supplier lead time in days.
- Safety stock equals peak daily units multiplied by buffer days. Use three to five buffer days for steady sizes and seven to ten for snow belt winter sizes.
- Reorder point equals lead time demand plus safety stock. Trigger an order when the shelf count reaches that number.
- Order quantity equals the reorder point multiplied by two, rounded up to the supplier case pack.
Buffer days are the only judgment call in the formula. Ten buffer days on a size that sells two sets a week wastes rack space and cash. Three buffer days on a snow tire in Minnesota in November sells the customer to a competitor.
Example: a 225/65R17 all season
Example: 225/65R17 all season
| Input | Value | Where it comes from |
|---|---|---|
| Average daily units | 2.0 | last 90 days of sales |
| Peak daily units | 4.0 | best week of the past year |
| Supplier lead time | 3 days | regional warehouse terms |
| Lead time demand | 6 | 2.0 x 3 |
| Safety stock | 12 | 4.0 x 3 buffer days |
| Reorder point | 18 | 6 + 12 |
| Order quantity | 36 | 18 x 2 |
This shop orders when the rack drops to 18 and buys 36. If lead time slips to five days, lead time demand becomes 10 and the reorder point becomes 22. Lead time is the input that moves most often, so recheck it each quarter.
Safety stock for the winter rush
Quebec requires winter tires from December 1 to March 15, so Montreal shops build tread stock, bay time and French counter scripts around November. The Quebec winter tire law page walks through that build.
Winter compounds and deeper tread patterns also shift which sizes matter, as Wikipedia's winter tire overview explains. Build the reorder point from November peak units, then drop buffer days back in April.
Turnover shows whether the points are right
Turnover equals annual units sold divided by average units on hand. A size that turns twice a year is overpriced, overstocked, or fading. Aim for four to six turns on all season sizes and two to three on winter sizes.
Tires on the rack are cash standing still, which is why stock planning and cash planning are one job in this trade. The tire shop bookkeeping and cash flow basics page shows how deposits, collected fees and warranty labor move through that cycle.
Where repair limits change the count
Tires at 2/32 inch or less must be replaced and cannot be repaired, per NHTSA tire guidance. Those units leave the rack and the count, which lifts replacement demand in the same sizes.
Nail location and injury count decide the rest. The tread repair versus replacement guide gives the counter a checklist that holds up with a customer standing there.
Uneven wear from cupping and feathering brings tires back early too, and Wikipedia's tire tread article lists the usual causes. A shop that sees those patterns often should raise safety stock on the replacement sizes that match.
Reviewing the numbers each quarter
- Pull 90 days of sales by size.
- Update supplier lead times.
- Recompute reorder points for every size above one unit a day.
- Flag sizes under two turns for removal.
- Rebuild safety stock before September and before the winter changeover.
