While overall heavy-duty parts prices have risen 5.7% since early 2024, tank truck fleets face a steeper climb in the critical chassis and driveline categories that keep their specialized equipment running.

FinditParts recently launched its first Heavy-Duty Price Index (HDPI), a new monthly benchmark utilizing real supplier inventory data rather than surveys to track parts costs. The September 2026 report reveals that while headline inflation is cooling, the pricing pressure is spread unevenly across component categories—exposing bulk haulers to hidden cost spikes.

“For tank truck fleets, that unevenness matters more than the average,” FinditParts CEO Matt Schweickert told Bulk Transporter.

“The categories climbing fastest are the chassis and driveline parts that keep specialized bulk equipment on the road, and with manufacturer-level prices still climbing, not all of that cost has reached fleets yet. The executives who manage this best won’t budget off a single inflation number. They’ll plan equipment acquisitions and stock critical maintenance parts category by category, and move earlier on the components where costs are still climbing.”

The real cost of parts

The HDPI tracks roughly 3 million unique in-stock SKUs across about 900 inventory locations, representing approximately $7 billion in inventory value at supplier cost. By measuring prices like-for-like on a SKU-by-SKU basis, the index provides a far more granular picture than broader national economic indicators.

In August 2026, federal data sent conflicting signals regarding motor vehicle parts, with the Consumer Price Index (CPI) showing a 0.9% year-over-year rise while the Producer Price Index (PPI) indicated a 3.3% increase. The HDPI, built specifically for the commercial vehicle sector, highlights that heavy-duty parts have outpaced both.

A major reason federal metrics lag commercial realities is composition: CPI samples 80,000 prices across the entire consumer economy, and about 85% of its motor vehicle parts sub-index is composed of tires. The HDPI isolates heavy-duty replacement components directly off distributor shelves.

Uneven category impacts

The most significant takeaway for equipment managers is the vast divergence in cost increases among different component groups. Key findings from the inaugural HDPI report include:

• Overall increases: Heavy-duty parts cost 5.7% more than they did in January 2024, pushing the overall HDPI to 105.7 in September 2026.
• Category spread: Driveline and axle component prices surged 12.9% since January 2024, while other areas like HVAC parts have remained roughly flat at an index of 99.0.
• Manufacturer pressure: Prices at the manufacturer level are still climbing (up 1.9% year over year), serving as a leading indicator that additional cost increases will likely be passed downstream to distributors and fleets.
• Distributor trends: Distributors experienced less price easing in 2024 and saw sharper increases heading into 2025, holding higher price levels for longer durations.

“With the first Heavy-Duty Price Index, our aim was to give the industry something it hasn’t really had: a clear, bottom-up view of what heavy-duty parts actually cost, measured from real supplier inventory instead of surveys,” Schweickert said. “Prices are up 5.7% since early 2024, but the more useful finding is how unevenly that increase is spread.

“Driveline and axle components are up nearly 13%—while other categories have barely moved.”