All vehicles have inherent characteristics that, if not understood and monitored, can decrease a vehicle’s performance and create a dangerous scenario for the principal. There are numbers that represent these vehicle characteristics; most can be found in the owner’s manual.
The Security Driver does not need to understand the science behind these numbers. Still, they need to know how these numbers and changes in these numbers affect the principal and passengers’ safety and security.
The top five vehicle characteristics are:
- The vehicle’s maximum payload capacity
- The tire’s load rating.
- Tire pressure
- The vehicles Statics Stability Factor – SSF (difficult to find)
- Center of Gravity (difficult to find)
The wrong combination of these five vehicle characteristics can and has proven to be a problem.
The wrong combination is defined as:
- The vehicle’s payload at maximum or exceeded
- Low Tires Pressures
- The tire Load Rating has been exceeded.
- High Vehicle Center of Gravity
- A Low Vehicle Static Stability Factor (SSF)
The payload is defined as the combined maximum allowable weight of cargo, occupants, and optional equipment the vehicle is designed to carry. The payload indicates how many passengers and cargo the vehicle can accept. That number is set by the vehicle manufacturer and is vital to passengers’ safety and security.
You can also use Google to find the payload of your vehicle; as an example, if you want to find the payload of a Suburban, you would type in “Payload for Suburban,” This is an example of what you would get.
Somewhere on the vehicle, there is a sticker that will supply the payload numbers; this is an example.
Or you can find the numbers in the vehicle’s manual.
Improperly loaded vehicles or those that exceed the weight rating will have a dramatic effect on performance. Steering, maneuverability, braking, and acceleration are all affected. Most important, stopping distances are dramatically impacted.
The Tires Load Index and Load Carry Capacity
The load index explicitly indicates how much weight a tire can carry. To find your tire’s carrying capacity, look for the load index number on its sidewall.
The load index number indicates a tire’s carrying capacity when inflated to its maximum load-sustaining pressure. It corresponds to another number in an index, which tells you how many pounds of weight the tire can carry.
How to Read Speed Rating, Load Index & Service Descriptions
Static Stability Factor and Center of Gravity – SSF and CG
Another characteristic that can decrease vehicle performance and safety is the vehicle’s static stability factor (SSF). This is especially true in SUVs. Click here for more information.
Tire Pressure Basics
Maintaining correct tire pressure helps optimize tire performance and fuel economy. Correct tire inflation pressure allows drivers to experience tire comfort, durability, and performance designed to match the needs of their vehicles. Proper tire inflation pressure also stabilizes the tire’s structure, blending the tire’s responsiveness, traction, and handling.
Click here for more information on Tire Basics
Tire Pressure Monitoring System
Almost everyone has seen the tire pressure monitoring system (TPMS) warning light appear on the dashboard. It warns you that at least one or more tires are significantly under-inflated, possibly creating unsafe driving conditions. Pressure-sensing transmitters are mounted inside each tire and sent to a central computer (ECU), which displays the tire pressure readings on the dashboard. The problem is that the warning light on the instrument panel does not come on until there is a 25-percent drop in tire pressure. When the warning light displays, you and the passengers are in a very unsafe vehicle.