What do these numbers mean?
The above charts are for light to medium outrigger pads in 1.5" thickness and for medium to heavy duty pads in 2.5" thickness. The capacity figures shown are based on multiplying the PSI rating ( either 250 or 500 PSI) by the square area of the pad. The result is a huge number and reflects the total load each pad can hold when the load is spread over the whole pad. Since most equipment has 4 outriggers, this figure gets divided by 4 and then depending on the thickness and the size of the pad a safety factor calculation is applied to get to the actual load capability of each pad size and thickness.
Our pad materials (Polystone and Densetec) them selves show PSI ratings of 2600 to 2800 PSI. There are complicated calculations done by the factories math, physics and chemistry experts to come up with the PSI per thickness.

Soooo, what size pads should I buy???
To choose the correct pad size, it is recommended to multiply the area of your outrigger foot/shoe/plate by a minimum of 3 (4 is better) to calculate the outrigger pad size. For example : your shoe size is an 18" round plate with an area of 254 square inches, multiply the 254 by 3 = 762 square inches. This result means that you need to pick a pad with an area of at least 762 square inches (like a 32" square - 1024 area or 32" round - 804 area).
Make sure that the total lift weight ( the equipment, all accessories, the operator (yes, him too) and the lift load) is calculated correctly and you choose pads that have enough area and enough load capability to correspond to your total lift weight.
Choosing the thickness is another component to consider that's dependent on the total load and the ground conditions. Are you on gravel, rock, sand, concrete or in mud? The softer the ground is, the thicker the pad should be. When in doubt the safer choice is thicker pads.

Just a quick note from your old math teacher:
Remember how to calculate the area of a circle ?????  Yep, round pads only hold app. 78% of the load that square pads can carry since their area is a lot smaller. They are basically squares with their corners chopped off. Round pads are very popular since they can be rolled and don't have to be carried by team members. So make sure you buy the correct size. Some of our competitors show the same ratings for square and round pads - they obviously failed in math class....

And if you have any questions or comments, contact us at by calling or texting 770-594-8608 or send an e-mail to info@primetechincusa.com