輪胎硬度可能是改裝賽車一個重要因素。太硬的輪胎可能會犧牲汽車的牽引力, 而太軟的輪胎則可能會增強牽引力但卻會加速輪胎的磨損。 并且不相配的輪胎設置也許將嚴重影響汽車的操控性能。為了正常地設置汽車,有必要測量輪胎的硬度，而zui容易和zui有效達到測量目的的方式就是使用硬度計。
型硬度計依照ASTM （美國材料試驗協會）D-2240 標準， 是輪胎制造商用來測量輪胎橡膠硬度的測量儀。
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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