Tank Vehicles
Liquid surge, baffles and outage.
7.1 Driving tank vehicles
Definition: Tank vehicle — a vehicle carrying liquid or gaseous materials in tanks with an individual rated capacity of more than 119 gallons and an aggregate rated capacity of 1,000 gallons or more (permanently or temporarily attached).
- Liquid surge pushes the truck when you stop or start. Brake early and smoothly.
- Baffles reduce front-to-back surge but not side-to-side surge.
- Smooth-bore (unbaffled) tanks, such as food-grade tanks, surge the most.
- Outage: never fill a tank completely — liquids expand when warm.
- Tankers have a high center of gravity; take curves well below the posted speed.
Source: FMCSA — 49 CFR Part 383 — Commercial Driver's License Standards (eCFR current), 49 CFR 383.5 (tank vehicle definition). Updated: 2026-10-09