A trailer jack block is a load-bearing platform placed under a trailer's tongue jack or stabilizer jack foot to prevent the jack from sinking into soft ground and to add height on uneven terrain.
Trailer jack blocks solve a practical problem that comes up on every soft or unpaved site: a stabilizer or tongue jack driven directly into grass, gravel, or dirt will sink and shift under load, leaving the trailer unlevel and potentially destabilizing it. Jack blocks distribute the jack's point load across a wider base area, keeping the trailer stable. Many designs stack to add height when a single block doesn't provide enough clearance.
- Trailer jack block weight ratings typically range from 6,000 lbs per block (standard units) up to 25,000 lbs for heavy-duty versions.
- Jack blocks are used under both tongue jacks (front of trailer) and stabilizer jacks (corner legs) — the two are distinct jack types.
- Common jack block materials include high-density polyethylene (HDPE) rated for oil, UV, and grime resistance.
- Stackable jack block designs allow height adjustment in increments, useful when a single block height is insufficient for level setup.
- Jack blocks are not required on hard, level pavement — their primary use case is soft or uneven ground conditions.