Why put blocks under trailer jacks?

Blocks under trailer jacks prevent the jack foot from sinking into soft ground and provide extra height when the jack's built-in travel range isn't enough to level the trailer. Without a solid base, stabilizer and tongue jacks can dig into grass, gravel, or dirt and shift the entire rig.

On soft or uneven surfaces, a jack foot concentrates significant weight onto a small contact area — enough to sink several inches overnight on wet grass or loose gravel. Jack blocks spread that load across a wider footprint, keeping the trailer stable and the jack mechanism from bottoming out. On hard, level pavement, blocks are generally unnecessary; the benefit is specific to soft or uneven terrain where ground contact is the limiting factor.

• Jack blocks spread trailer jack load across a wider footprint to prevent sinking on soft ground.
• Stackable jack blocks add height in increments, extending a tongue jack's usable travel range on sloped sites.
• Heavy-duty jack blocks are rated to 6,000–25,000 lbs per block depending on model and construction.
• Jack blocks are rated for grass, gravel, and pavement; not a substitute for full leveling on steep slopes.
• Materials that resist oil, UV, and grime — such as high-density polyethylene — extend jack block service life significantly over wood or cheap plastic.