| 摘要 |
A new pneumatic radial ply truck tire 10 for use on steering axles has a tread 12 with a pair of centerline grooves 14 and a pair of shoulder grooves 16 that divide the tread 12 into a pair of shoulder rows 24, a pair of riding rows 26 and a center row 28. Lateral grooves 20 divide the rows into block elements 22. The centerline grooves 14 and shoulder grooves 16 have top, middle and bottom potions 30, 32, 34 and 36, 38, 40. The top portions 30, 36 have straight sides 42, 48 that are angled at top angles A1, A2 respectively. The middle portions 32, 38 also have straight sides 44, 50 that are angled at middle angles A3, A4 respectively. To provide the grooves 14, 16 with a general V-shape, it is preferred that the middle angles A3, A4 be greater than their respective top angles A1, A2 respectively. The bottom portions 34, 40 are U-shaped and have bottom widths X1 and bottom depths D1, D2 respectively. These U-shaped bottom portions 34, 40 are wide enough to permit a tread gauge to be inserted for measuring the non-skid depth yet, are narrow enough to prevent stones of significant size from entering. The lateral grooves 20 that extend across the two riding rows 26 and the center row 28 have top portions 58, 64 and bottom portions 60, 66. The bottom portions 60, 66 have second widths W2, W4 and second depths D4, D6 that extend to at least 50% of the tread non-skid depth D. The center row 28 and the riding rows 26 are formed at a tread arc radius TAR. The shoulder rows 24 have inside edges lowered a first distance D10 with respect to the tread arc radius TAR and outside edges that are raised a second distance D11 with respect to the tread arc radius TAR. This single radius plus mixed shoulder off-set design reduces irregular wear and helps in achieving equal pressure distribution across the surface of the tread 12. |
