Regulatory signs
Trucks Use Right Lane sign
Trucks and other heavy, slow moving vehicles must stay in the right lane except when passing.
- Tall rectangle
- White
- MUTCD R4-5
Shape and background first
Federal designation R4-5 in the MUTCD, the national standard every state signs to. Usually posted at the base of a long climbing grade on a multi-lane highway, where slow trucks would otherwise block faster traffic in every lane.
What the MUTCD specifies
Designation: R4-5
MUTCD Section 2B.38
Conventional road size: 24 x 30 in
Option: This sign may be used on a multilane through road to reduce lane changes caused by slower trucks.
Source: Federal Highway Administration, MUTCD 11th Edition (December 2023), Part 2, Table 2B-1; Section 2B.38, verified 2026-09-26.
What the test wants you to know
The mistake people make
The rule exists to keep faster passenger traffic flowing in the left lanes on grades and multi-lane highways, so a truck lingering in a passing lane here is committing a real violation, not just being inconsiderate. This sign is sometimes paired with a steep hill sign to test whether you understand why the restriction exists at that specific spot.
