Chapter 2: Speed Limits

Adhering to speed limits is a fundamental responsibility for every driver, crucial for both passing the driving exam and ensuring roadway safety. Speed is a primary factor in crash severity, and understanding how to manage it appropriately for various conditions is a hallmark of a skilled, defensive driver. This chapter covers Oklahoma’s Basic Speed Law, statutory limits, and special speed-related situations to prepare drivers for predictable and unpredictable road conditions.

The Basic Speed Law

Oklahoma law is built on a foundational principle known as the Basic Speed Law. This law states that a driver must not operate a vehicle at a speed greater than is reasonable and prudent under the existing conditions, regardless of the posted speed limit. The number on a speed limit sign indicates the maximum legal speed under ideal conditions—a clear, dry day with light traffic.

The Basic Speed Law requires drivers to consider all factors that affect their ability to stop safely. These factors include:

• Weather: Rain, fog, ice, or snow dramatically increase stopping distance and reduce visibility.
• Visibility: Drivers must be able to stop within the distance they can see ahead. At night or in fog, this means reducing speed significantly.
• Traffic: The volume and speed of other vehicles dictate a safe speed. Driving much faster or slower than surrounding traffic can be hazardous.
• Road Surface: Gravel, rough pavement, or roads covered in debris require lower speeds.
• Your Vehicle: The condition of a vehicle’s tires and brakes affects its stopping ability.

For example, driving 75 mph on a turnpike with a posted 80 mph limit during a heavy thunderstorm is a violation of the Basic Speed Law. Even though the driver is below the maximum limit, the speed is not reasonable or prudent for the hazardous conditions. The core principle is to always be able to stop within the “assured clear distance ahead.”