HANOVER, Germany—Continental A.G. has begun producing tires with an "HL" load index, a new standard that yields tires capable of carrying heavier loads at the same pressure as those built to the "XL" standard used up to now.
Continental said it has adopted the HL standard for certain OE tires destined for fitment on larger, more powerful cars and SUVs with electric or hybrid drive that tend to be heavier than more conventional vehicles.
The German company claims to be the first tire maker to produce products with the HL index.
Tires built to meet the HL standard require a number of changes to the structure and rubber compounds, Continental said, such as a reinforced bead and "enhanced" casing contour.
"We were dealing here with tradeoffs that needed resolving at a very high level," Stefan Habicht, head of the development project for the HL tires at Conti, said in a statement.
"In terms of construction, we reinforced the bead and enhanced the contour of the tire to reduce tire/road noise. At the same time, we also optimized the pattern compound. As a result, we were able to achieve low rolling resistance, ensure precision handling and keep mileage at its customary high level."
Products that meet the new maximum load capacity must display the HL code on the sidewall ahead of the size, for example "HL 245/45 R19 101 Y XL."
In this example, the tire's load capacity is 1,819 pounds (825 kg), which translates to a load index of 101 (or a 10 percent increase over the familiar XL standard of 1,653 pounds).
Passenger tires of this size built to the SL standard, adequate for many cars, up to and including mid-range models, can take a maximum load of 1,477 pounds (670 kg or load index 94). That makes the load capacity of the new HL tires almost 25 percent higher.
Looking ahead, Continental said it expects to see growing demand for tires with the new HL code.
The HL standard is the work of the European Tyre & Rim Technical Organization (ETRTO), a Brussels-based technical standards body. Among its stated goals is to "establish common engineering dimensions, load /pressure characteristics and operational guidelines" and to "promote the free exchange of technical information appertaining to pneumatic tires, rims and valves."