AboutBarry Smith Expertise I have over 30 years experience in the design, manufacturing, and
testing of tires. I have served as the technical advisor to the "800"
number. I have authored or co-authored many publications - usually
without credit. I can answer almost any technical question, but
please don`t ask me to compare brands. I probably have prejudices because of
my work experience.
Experience Member SAE (Society of Automotive
Engineers)
Member Tire Society (Tire Technical Organization)
SCCA Regional Competiton License holder
Authored many training manuals on tires, their care and use.
Expert: Barry Smith Date: 7/16/2008 Subject: Rear End Sway Under Load
Question Barry,
I have a Dodge Ram 5500 with a wrecker body. The tires are Goodyear 225/70R19.5 with a load range F. Front tires are "all position" (according to Dodge description)G647 RSS, and rear tires are "traction" G622 RSD.
Empty the vehicle drives just fine. Towing a car I get rear end sway. The body upfitter says that the tire tread is too aggressive and that is causing the problem. Others have suggested that the load range could cause the problem but the tread will not.
Can my tires be the cause of the sway? If so, can the inflation be adjusted to correct the problem?
Answer Bob,
It is possible that the tire pressure is causing the problem.
So the first step in the process is to find the vehicle placard and see what it says. This isn't a "Light Vehicle" as defined by NHTSA, but I'll bet the placard is in the same position as required by NHTSA - near the drivers door - meaning the door or doorpost.
The second step would be to compare the tire size and pressure to what you are running!
Check this out and let me know what you find and we'll discuss what to do next.
