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Show DON'T S'KID YOURSELF Winter Tests Indicate Chains Are Safer Than New Safety Tires There has been an alarming upswing in traffic accidents during re-icent re-icent years. And the most disturbing aspect of the highway accident picture, according to the automotive safety foundations, is the mount-ling mount-ling ratio of rural fatalities. Excessive speed and inadequate control by police and the courts are cited as the underlying factors in last year's 'record, showing rural traffic deaths outnumbering urban fatalities by about two and a half to one. Winter, the most dangerous season sea-son of the year on American highways, high-ways, is in full force throughout the nation. Highways in many areas have never been so dangerous. How slippery and dangerous is an icy road compared to a snowy one? How safe are "winter" tires? How do they actually compare with tire chains? In an effort to answer these and other important questions for the benefit of the puzzled motorist, the National Safety Council's committee commit-tee on winter driving hazards conducted con-ducted a two-week series of tests t Pine Lake, liear Chntonville, Wis., last winter. Results are now m-piled m-piled and are being made public for the first time. 2,000 Tests Run Nearly 2,000 individual test runs were made to test 22 representative tread designs of various tires for stopping, "go" traction, and cornering corner-ing ability on snow and ice. The special spe-cial "winter" tires fall into three classifications: (1) Those with specially spe-cially impregnated treads containing "breakout" material such as sawdust, saw-dust, peanut shells or rock salt: ethers have steel wool, chips or steel coils embedded which is intended to be "abrasive"; (2) surface treatment treat-ment consisting of multiple lacerations, lacera-tions, " knife or saw cuts, and (3) various shapes of knobs, studs, lugs or ribs. All are supposed to give surer footing on the variety of slick or impassable surfaces encountered by winter drivers. Ross G. Wilcox, traffic engineer en-gineer for the National Safety Council, In summarizing the results, re-sults, said that in general, while the performance of some of the specialized tires showed a definable def-inable improvement for some specific conditions over regular tires, their over-all improvement improve-ment was not great enough to warrant less care or elimination of tire chains when driving on slippery surfaces. "As an example, the stopping distance dis-tance on glare ice of the best specialized spe-cialized tire tested is still about eight times the stopping distance on dry concrete," Wilcox said. "We found that steel tire chains of the reinforced type are far superior su-perior to the best of the special winter tires tested on snow and ice, and show a consistent improvement over conventional natural rubber tires averaging 46 per cent in stopping stop-ping ability, and 475 per cent In tractive ability." The tests also showed, he said, that natural rubber is 10 per cent to 50 per cent superior to cold synthetic syn-thetic rubber in stopping and traction trac-tion on snow and ice, although synthetic syn-thetic is about 7 per cent superior to natural rubber in cornering speed (resistance to side skids) on ice. Most passenger car tires in use today, to-day, and those now being manufactured manu-factured have treads that are all or part "cold synthetic rubber," which wears better. Truck tires need and do have more natural rubber. Tests Summary Averaging test results of all types on both glare ice and loosely packed snow, both for stopping, turning, and forward traction ability, the engineers en-gineers established a system of "rating" the over-all performance of each type of equipment. In all cases comparisons were made with a convention rib type tread of natural natu-ral rubber, or a duplicate tread of cold synthetic. Results of the conventional con-ventional natural rubber tread were considered the standard or baseline for comparative purposes and it was rated at 100. Results of the "performance summary" sum-mary" showed: Conventional natural rubber tires, 100; conventional cold synthetic tires, 89; winterized tires, 108; mud-snow tires, 113; winterized mud-snow tires, 126; tire chains on ordinary tires, 286. On some tests, and on some surfaces, Wilcox noted, some of the special winter tires actually were inferior In performance to regular tires. The test revealed that changing temperatures or sunshine made a big difference, as much as 130 per cent, in skid distances on ice. At four degrees below zero, for example, ex-ample, tires without chains may stop in about 110 feet; but the same care, at the same 20 m.p.h. speed, takes about 250 feet on the same ice at around 30 degrees above zero. This variable has led many a driver to disaster. He thinks he's pretty skillful, after no trouble on near zero ice, only to lose control a little later. When the sun comes out, for example, and puts a moist film on the ice or nard-packed snow, then look out. This, engineers point out. is another reason for chains. Their performance is comparatively consistent con-sistent from zero to melting point on ice or snow. Other Tests Made The special winter tires were not tested on hard packed snow. That will be done in official tests this winter. Previous committee tests showed that regular tires skid about 75 feet on traffic-packed snow at 20 m.p.h. after brakes are applied, and tire chains about 38 feet. "The tests likewise showed," Wilcox said, "that cars with hydraulic and fluid couplings with standard, automatic, or em 1-automatic transmissions lend themselves to better con- trol on Ice than cars with convention con-vention clutch and transmission. "With the conventional clutch and transmission on wet ice, which is very slippery, a hard brake application applica-tion can lock the rear wheels just long enough to stall the engine, which will hold the rear wheels in a locked condition and may cause the car to go into a spin. This accidental ac-cidental stalling of the engine is not likely to occur with a hydraulic or fluid coupling, and if it should occur, will not lock the rear wheels." In conclusion, while the performance perform-ance of several of the specialized tires used in the test showed definite defi-nite improvement for specific condition con-dition over conventional tires, their over-all improvement is not great enough to warrant less care or precaution pre-caution when driving on slippery surfaces with these tires than with conventional tires. As an example, the stopping distance on glare ice of the best specialized tire tested is still about eight times the normal stopping distance on dry concrete. And it must be stressed that except ex-cept for several specific and unusual un-usual surface conditions, tire chains of the type used in the tests are far superior to the best of the tires tested on snow and ice, showing an improvement over conventional natural rubber tires averaging 46 per cent in stopping ability and 475 per cent in traction ability. These tests by the National Safety Safe-ty Council's committee on winter driving hazards were made to end confusion over conflicting claims which involve traffic safety during I winter months. |