轮胎硬度可能是改装赛车一个重要因素。太硬的轮胎可能会牺牲汽车的牵引力, 而太软的轮胎则可能会增强牵引力但却会加速轮胎的磨损。 并且不相配的轮胎设置也许将严重影响汽车的操控性能。为了正常地设置汽车,有必要测量轮胎的硬度，而zui容易和zui有效达到测量目的的方式就是使用硬度计。
型硬度计依照ASTM （美国材料试验协会）D-2240 标准， 是轮胎制造商用来测量轮胎橡胶硬度的测量仪。
DUROMETER TYPES | APPLICATIONS | INDENTOR SHAPE | MAIN SPRING |
TYPE A | Soft rubber, plastics, and elastomers, printer's rolls. | Flat Cone Point 35° Included Angle | 822 GM 1.81 LB. |
TYPE D | Hard rubber and plastics such as thermo plastics, flooring and bowling balls. | Sharp Cone Point 30° Included Angle | 4536 GM 10.0 LB. |
TYPE B | Harder elastomers and plastics. Paper and fibrous materials, Use above 93 Duro A. | Sharp Cone Point 30° Included Angle | 822 GM 1.81 LB |
TYPE C | Medium hard elastomers and plastics. Also useful to avoid surface marks. | Flat Cone Point 35° Included Angle | 4536 GM 10.0 LB |
TYPE DO | Dense granular material, textile windings. | 3/32" Spherical | 4536 GM 10.0 LB |
TYPE O | Very soft elastomers, textile windings, soft granular materials. Use below 20 Duro A. | 3/32" Spherical | 822 GM 1.81 LB |
TYPE OO | Light foams, sponge rubber gels, animal tissue. | 3/32" Spherical | 113 GM |
TYPE OOO | Ultra soft gels and sponge rubber. | 1/2" Spherical | 113 GM |
TYPE M | Materials as thin as .050" | Sharp Cone Point 30° Included Angle |
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