March 17, 2010
There's nothing 'light' about light truck tires
How to avoid confusion about load-carrying capacity
By: Kevin Rohlwing
The OE tire size on the Ford Excursion is LT265/75R16 Load Range E, with a load index of 123. How does a P265/75R16 with a load index of 114 compare? What is the reduction in maximum load?
I had spent the year prior to my 16th birthday working at my father’s tire shop unloading and stocking tires in between janitorial duties and whitewall scrubbing. So before I could legally drive a car, I thought I understood the differences between passenger and light truck tires.
The first thing I noticed was the “LT” molded on the sidewall, which dictated to me where they needed to be inventoried. They also were a lot heavier, which stunk because the light truck tire storage area was up a narrow flight of stairs to a second floor mezzanine.
At the time, some of them had 16.5-inch bead diameters, which were easy to spot because the bead was at a sharper angle as opposed to the “square” beads of passenger tires. Radial light truck tires also were easy to identify because the letter “R” would be molded on the sidewall, and they were even heavier yet. Other than that, they seemed to be just like passenger tires only a little bigger.
I know better today. But not everybody does.
To the uninitiated, that’s understandable. It doesn’t appear that there is much of a difference between a pickup truck or sport utility vehicle (SUV) that uses passenger tires and one that uses light truck tires. Also, the service procedures for passenger and light truck tires are performed on the same equipment and, for the most part, they are similar in nature.
The most significant difference for consumers is probably the price — and that’s where the trouble starts.
Les Cook, manager of tire application engineering for Cooper Tire & Rubber Co., spends a lot of his time dealing with consumer problems in the field. He says they ultimately end up as a training seminar for the dealer who sold the tire.
“With light truck tires, I’m seeing a lot of misapplication that’s being promoted by dealers, and whether they realize they’re doing it or not, it’s a problem for the industry and it needs to be straightened out.”
In most of these cases, the customer drives a large SUV or pickup truck that requires a light truck tire with a higher load-carrying capacity than a passenger tire of the same size. The dealer thinks he’s doing the customer a favor by selling him a less expensive, P-metric tire.
“I recently had a complaint on 3/4-ton van that required Load Range E tires, but the dealer installed a set of P-metric passenger tires with a load index that was much lower. The van was used to pull a boat, and within the first 90 miles, cracks started forming on the sidewall.
“Fortunately, we were able to get the passenger tires off the van and replace them with a set of light truck tires that conformed to the placard before they failed in service,” says Cook. “If the dealer had followed the information on the placard to begin with, the whole problem could have been avoided.”
Sign up for our Enews and receive the latest news, trends, and product information right in your e-mail inbox.