Alcohol and high speed were believed to be factors in the crash.
State troopers responded to the scene, on Highway 512 at 94th Avenue East, at about 10:45 p.m. Thursday after receiving a report of a serious crash.
The pickup driver, identified as David B. Rogers, 46, of Puyallup, was found dead in the back seat of his vehicle, which wound up in the highway median after the crash.
A preliminary investigation found that a westbound 2012 Peterbilt semi was hauling a tanker trailer with a full load of gasoline uphill at about 30 to 35 mph when a 2011 Ford F150 pickup headed the same direction slammed into the rear of the tanker trailer at high speed.
The pickup swerved to the left after the impact and came to a rest in the highway median.
There were no spills or leaks from the tanker truck.
The accident remains under investigation.