GREENVILLE, S.C.-After receiving complaints that the MXV4 tire fitted as original equipment on the 1994 Honda Accord EX can cause an electro-static discharge, Michelin North America has ``modified'' some of its tread compounds containing silica. Some toll booth attendants in Illinois reportedly have received a static shock when collecting tolls from Accord drivers. One even was knocked to the ground, according to a story in the Chicago Tribune.
And in Boston, Accord owners called into National Public Radio's ``Car Talk'' program, voicing complaints of radio static when driving over manhole covers and steel-reinforced bridges.
Honda officials were unavailable for comment.
Michelin said in a prepared statement it ``recognizes that under specific environmental conditions, some cars fitted with certain types of our tires can cause people to experience an occasional electro-static discharge.''
The company stopped manufacturing the suspect compound-used on tires on various Honda Motor Co., BMW A.G. and Mercedes-Benz A.G. models to reduce rolling resistance-in early spring. Michelin is reviewing replacements for the tires on a case-by-case basis. The number of complaints recorded or why the majority originated from Illinois is unknown.
The incidence of static discharge depends on a number of factors, including road surface, temperature and humidity, a Michelin spokesman said.
``Static shock has been reported in vehicles other than the Honda Accord with tires other than Michelin's,'' he said. ``I know that other companies use compounds that essentially can have the same effect.''
Pirelli S.p.A. has used silica in its motorsports tire lines since the mid-1980s and just released its P Zero System, which uses substantial amounts of silica, in the U.S. ``We've had no problems,'' a company spokesman said. ``We foresee a considerable future for silica.''
Bridgestone/Firestone Inc. and General Tire haven't introduced silica tires to the market, but they are developing low rolling resistance tires using the material. Goodyear has worked with silica in the past, yet has no plans to introduce any tires with the filler.
A General Tire spokesman said its silica compounds did not encounter problems with static electricity in testing, and the firm anticipates introducing its silica line on future car models.
However, automakers in Japan warned Bridgestone Corp. of the condition and Bridgestone/Firestone Inc. is ``trying to find how we can get away from this problem,'' said Hiromi ``Mike'' Hamaya, president of the firm's technology subsidiary in Akron.
The more silica used, the more static tends to be charged in the tires, he said.
Mr. Hamaya also agreed with Michelin, saying asphalt roads, lower humidity and temperatures, and certain vehicle makes can bring on the discharge.
U.S.-based tire makers have been hesitant to use silica because it's difficult to mix and costs more than carbon black, he said. ``Silica is more widely used in Europe, and it hasn't been an issue there. But we have thousands of toll booths throughout the U.S.''
Goodyear hasn't experienced any static electricity issues in its research, yet it also suspects the incidents are related to higher silica content.
``It seems not to happen in tires that have more carbon black,'' a company spokesman said. ``Conventional tires seem to do a better job dissipating the static electricity.''
Goodyear, which has been experimenting with silica since the early 1970s, doesn't use the material in its tires because the benefits don't justify the price and trade-offs, he said.