115% Rule

The 115% Rule is a motorsport regulation that requires drivers to achieve lap times within 115% of the fastest qualifying time to be eligible to start a race.

Think of it this way: if the fastest driver completes a lap in 60 seconds, any driver wanting to race must complete their qualifying lap in 69 seconds or less (115% of 60 seconds). This rule acts as a minimum speed requirement to participate in the actual race.

The primary purpose of this rule is safety. Cars that are significantly slower than the rest of the field can create dangerous situations when faster cars try to overtake them. By setting a minimum pace requirement, race organizers ensure all participants can maintain reasonably competitive speeds.

Different racing series use variations of this percentage rule. NASCAR employs the 115% rule, while Formula One uses a stricter 107% rule, and IndyCar uses an even tighter 105% rule. Formula E applies a 110% threshold. The specific percentage depends on the characteristics of each racing series and their safety requirements.

The rule is typically applied during qualifying sessions, where drivers attempt to set their fastest possible lap times. Those who fail to meet the percentage requirement are usually excluded from the race start. However, race stewards sometimes have discretion to allow slower drivers to participate if they showed adequate pace during practice sessions.

Some racing series adjust their percentage requirements based on track conditions. For example, on tracks with abrasive surfaces that cause significant tire wear, the threshold might be relaxed since lap times can vary more dramatically throughout a session.

This regulation helps maintain competitive integrity while ensuring that all participants on track can operate at speeds that don't compromise the safety of other drivers or create unnecessary racing incidents.