The following is pretty technical stuff. It is designed for those clients and readers who are interested in some of the more technical/scientific issues surround auto accidents. If you would like to discuss these theories with an attorney please call 800-300-0001.
The Static Stability Factor (SSF) is a computation of your vehicle, several geometric properties and its susceptibility to rolling over in an accident. This figure will tell how top heavy your car is, and whether it will roll over in an accident.
Let’s take a closer look at the SSF. If the vehicle has an SSF, this number will equal the track width of the vehicle and be calculated over the height of the vehicle’s center of gravity. The mathematical equation looks like this:
SSF = T/2H
The width of the track (your “T”) is considered the measured distance between the middle of the right and left tires, as measured along the wheel axle. Imagine placing a rope on the ground, under the car, in between the two rear tires. The track width is measured by the rope correctly, if the rope starts at the middle of one rear wheel, and goes across to the middle of the other rear wheel. The center of gravity (your “h” times the number “2”) is measured by approximately the top of the wheel area, (or slightly higher) down to the ground. (To figure out these numbers for yourself, you would plug in the values and divide for an answer, or consult your manufacturer’s owners manual or online sources for the SSF).
This center of gravity is not an imaginary line, like the line of the earth’s equator. It is a formal center of the car’s gravity as determined by laboratory testing. The scientists testing for the car center of gravity will check the car’s height above the level of the ground, and calculate the mass, or how much the car weighs. If this sounds like heady stuff, it actually is. The lower the SSF number for the car, the higher the likelihood that the vehicle will roll over in an accident (single vehicle crash).
Okay, let’s keep going. If the SSF factor is very high, that means that the car is stable and not as top heavy as a SSF factor that is a lower number. For example, some pickup trucks and SUVs have high SSF values (1.00 to 1.30). Many passenger cars have SSF values of 1.30 to 1.50 (higher than just the 1.00 range).
What does this all mean? Remember we were wondering about the center of gravity just a few minutes ago. With an SUV, the tires are higher off the ground, the top of the tire is higher and you step up into the SUV higher off the ground as well. This makes the center of gravity higher for that truck or SUV.
Now imagine a passenger car. You step into it, and often have to crouch down to get into the seat, need to watch your head as you get into the car, and are able to reach the door easily to close it behind you. This center of gravity is closer to the ground.
Why is this important? The SSF measurements can help predict how your car or SUV would do if it were to rollover. The risk that your particular car or SUV would roll over is determined with a star rating, of one to up to five stars (applies to cars 2004 and newer). Since most rollovers are a result of the car or SUV hitting something, or going into a ditch, curb or shallow area, the SSF measures how likely your car or SUV would roll over.
What should you do with this information? It might help you as you are planning to buy a new or pre-owned car that is a 2004 or newer model year. You might also consider that even with an older vehicle, you can check the manufacturer’s manual to determine if your SSF is high or low. Just being aware of this rating may give you more information regarding your vehicle and how it is rated against other cars and trucks.
