IVALO, Finland-Continental A.G., hoping to keep pace with the industry's rapid drive toward fuel economy, is launching a line of V-rated passenger tires that employ silica-based tread compound technology, which lowers rolling resistance without sacrificing wet grip or tread wear. Known as the ``Conti EcoContact CP'' (CP for ``Concept Plus''), the new tire line uses both silica and more highly activated carbon blacks in combination with blends of synthetic and natural rubber for a tread compound that, in concert with optimized casing shape, yields a 25- to 30-percent advantage in rolling resistance compared with currently available tires in this category.
The ``CP'' is seen as an answer to Groupe Michelin's silica-based ``Green X'' technology, which the French firm has applied to most of its tire lines over the past four years, and thereby gained a slight advantage over competitors in original equipment fitments.
Conti's new product line builds on the concept of the firm's S- and T-rated ``EcoContact,'' launched two years ago as both an economically and ecologically sound product because it uses a higher percentage of renewable resources (natural rubber) while using less material overall. The EcoContact will be upgraded to H-rated later this year.
Conti will attempt to draw attention to the rolling resistance advantage by marking its CP tires on the sidewalls with a rolling resistance symbol ``CR'' and value.
CR values are determined by laboratory tests accepted by vehicle manufacturers and conducted by independent test labs, Conti said. A CR value of 1.0, for example, means that the braking action of a fully laden vehicle is equal to 1 percent of the total weight.
Whether this CR value becomes accepted industrywide remains to be seen. Other manufacturers had not responded to queries by presstime. Michelin, however, campaigned last year in the U.S. for a rolling resistance standard to be included in the Uniform Tire Quality Grading standards.
Using silica as a reinforcing agent helps tire makers overcome the compromise between rolling resistance and wet grip, but also introduces wear sensitivity problems, Conti said.
To help counteract this, the firm chose carbon black types normally associated with truck tires. Combined with an extremely flat cross section and redesigned sidewalls, these changes help to maintain and even improve wear, Conti said.
Conti did not divulge the cost of development of the CP line, nor any investment costs associated with revamped mixing and processing steps necessary for silica-reinforced compounds. The cost increase for a silica-based tire is estimated to be 2-12 percent more than a comparable ``standard'' tire.
The CP line will be introduced this summer in five 15-inch sizes covering about 80 percent of the fitments of the targeted major car lines in Europe. The firm gave no indication as to its North American plans for CP or any other use of the technology.
A winter tire line using the silica technology also is in the final development stages for a winter 1994-95 launch, Conti said.
Tire Business for 1994