FMVSS No. 138 Tire Pressure Monitoring Systems (49 CFR 571.138)

What FMVSS No. 138 Tire Pressure Monitoring Systems (49 CFR 571.138) requires

FMVSS No. 138 (Section 571.138) requires a Tire Pressure Monitoring System (TPMS) on passenger cars, multipurpose passenger vehicles, trucks, and buses with a GVWR of 4,536 kg (10,000 lb) or less (S2). Per S4.2(a) the low tire pressure telltale must illuminate not more than 20 minutes after one or more tires (up to four) reach a pressure 25 percent or more below the placard cold inflation pressure (or the applicable minimum, whichever is higher). Per S4.4(a) a malfunction telltale must warn the driver not more than 20 minutes after a TPMS malfunction occurs.

Pillar: Automotive & Mobility · Authority: NHTSA / US Department of Transportation · Version: 1.0.0 · Last updated: 2026-06-26

Primary source: https://www.ecfr.gov/api/renderer/v1/content/enhanced/current/title-49?part=571&section=571.138

SHA-256 integrity: 70df99978b65c9e0ca6bf9ceacb0ce38e8c064248b7553699022cd2ebbbb7fc3

Primary Citations — 6 traced to source

• 49 CFR 571.138 - Standard No. 138; Tire pressure monitoring systems, § 571.138 S2 - Application (GVWR 4,536 kg or less)
• 49 CFR 571.138 - Standard No. 138; Tire pressure monitoring systems, § 571.138 S4.2(a) - low tire pressure telltale within 20 minutes at 25 percent below placard

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