タイヤの外径についての小話
タイヤの外径を知りたい場合は…幅×扁平率×2+15×25.4mmで算出できます。下の表は、タイヤの各サイズにおける外径を算出したものです。インチアップ、ダウン時のタイヤ選びの参考にしていただければ幸いです。
(*注)表の数値はあくまでも参考で、メーカーや銘柄により、細かな数値は変わります。詳しくは、タイヤ販売店の店員さんに尋ねるか、タイヤのカタログを参照してください。
幅 |
扁平率 |
インチ |
10 |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |
20 |
135 |
60 |
416 |
466.8 |
492.2 |
|
|
|
|
|
|
|
135 |
65 |
429.5 |
480.3 |
505.7 |
|
|
|
|
|
|
|
135 |
70 |
443 |
493.8 |
519.2 |
|
|
|
|
|
|
|
135 |
80(SR) |
470 |
520.8 |
546.2 |
|
|
|
|
|
|
|
145 |
60 |
428 |
478.8 |
504.2 |
|
|
|
|
|
|
|
145 |
65 |
442.5 |
493.3 |
518.7 |
|
|
|
|
|
|
|
145 |
70 |
457 |
507.8 |
533.2 |
|
|
|
|
|
|
|
145 |
80(SR) |
486 |
536.8 |
562.2 |
|
|
|
|
|
|
|
155 |
55 |
424.5 |
475.3 |
500.7 |
526.1 |
|
|
|
|
|
|
155 |
60 |
440 |
490.8 |
516.2 |
541.6 |
|
|
|
|
|
|
155 |
65 |
455.5 |
506.3 |
531.7 |
557.1 |
|
|
|
|
|
|
155 |
70 |
471 |
521.8 |
547.2 |
572.6 |
|
|
|
|
|
|
155 |
80 |
502 |
552.8 |
578.2 |
603.6 |
|
|
|
|
|
|
165 |
55 |
435.5 |
486.3 |
511.7 |
537.1 |
562.5 |
|
|
|
|
|
165 |
60 |
452 |
502.8 |
528.2 |
553.6 |
579 |
|
|
|
|
|
165 |
65 |
468.5 |
519.3 |
544.7 |
570.1 |
595.5 |
|
|
|
|
|
165 |
70 |
485 |
535.8 |
561.2 |
586.6 |
612 |
|
|
|
|
|
165 |
80(SR) |
518 |
568.8 |
594.2 |
619.6 |
645 |
|
|
|
|
|
175 |
40 |
|
|
470.2 |
495.6 |
521 |
|
|
|
|
|
175 |
45 |
|
|
487.7 |
513.1 |
538.5 |
|
|
|
|
|
175 |
50 |
|
|
505.2 |
530.6 |
556 |
|
|
|
|
|
175 |
55 |
|
|
522.7 |
548.1 |
573.5 |
|
|
|
|
|
175 |
60 |
|
|
540.2 |
565.6 |
591 |
|
|
|
|
|
175 |
65 |
|
|
557.7 |
583.1 |
608.5 |
|
|
|
|
|
175 |
70 |
|
|
575.2 |
600.6 |
626 |
|
|
|
|
|
175 |
80 |
|
|
610.2 |
635.6 |
661 |
|
|
|
|
|
185 |
40 |
|
|
478.2 |
503.6 |
529 |
|
|
|
|
|
185 |
45 |
|
|
496.7 |
522.1 |
547.5 |
|
|
|
|
|
185 |
50 |
|
|
515.2 |
540.6 |
566 |
|
|
|
|
|
185 |
55 |
|
|
533.7 |
559.1 |
584.5 |
|
|
|
|
|
185 |
60 |
|
|
552.2 |
577.6 |
603 |
|
|
|
|
|
185 |
65 |
|
|
570.7 |
596.1 |
621.5 |
|
|
|
|
|
185 |
70 |
|
|
589.2 |
614.6 |
640 |
|
|
|
|
|
185 |
80(SR) |
|
|
626.2 |
651.6 |
677 |
|
|
|
|
|
195 |
40 |
|
|
|
511.6 |
537 |
562.4 |
|
|
|
|
195 |
45 |
|
|
|
531.1 |
556.5 |
581.9 |
|
|
|
|
195 |
50 |
|
|
|
550.6 |
576 |
601.4 |
|
|
|
|
195 |
55 |
|
|
|
570.1 |
595.5 |
620.9 |
|
|
|
|
195 |
60 |
|
|
|
589.6 |
615 |
640.4 |
|
|
|
|
195 |
65 |
|
|
|
609.1 |
634.5 |
659.9 |
|
|
|
|
195 |
70 |
|
|
|
628.6 |
654 |
679.4 |
|
|
|
|
195 |
80 |
|
|
|
667.6 |
693 |
718.4 |
|
|
|
|
205 |
40 |
|
|
|
519.6 |
545 |
570.4 |
595.8 |
|
|
|
205 |
45 |
|
|
|
540.1 |
565.5 |
590.9 |
616.3 |
|
|
|
205 |
50 |
|
|
|
560.6 |
586 |
611.4 |
636.8 |
|
|
|
205 |
55 |
|
|
|
581.1 |
606.5 |
631.9 |
657.3 |
|
|
|
205 |
60 |
|
|
|
601.6 |
627 |
652.4 |
677.8 |
|
|
|
205 |
65 |
|
|
|
622.1 |
647.5 |
672.9 |
698.3 |
|
|
|
205 |
70 |
|
|
|
642.6 |
668 |
693.4 |
718.8 |
|
|
|
205 |
80(SR) |
|
|
|
683.6 |
709 |
734.4 |
759.8 |
|
|
|
215 |
40 |
|
|
|
527.6 |
553 |
578.4 |
603.8 |
629.2 |
|
|
215 |
45 |
|
|
|
549.1 |
574.5 |
599.9 |
625.3 |
650.7 |
|
|
215 |
50 |
|
|
|
570.6 |
596 |
621.4 |
646.8 |
672.2 |
|
|
215 |
55 |
|
|
|
592.1 |
617.5 |
642.9 |
668.3 |
693.7 |
|
|
215 |
60 |
|
|
|
613.6 |
639 |
664.4 |
689.8 |
715.2 |
|
|
215 |
65 |
|
|
|
635.1 |
660.5 |
685.9 |
711.3 |
736.7 |
|
|
215 |
70 |
|
|
|
656.6 |
682 |
707.4 |
732.8 |
758.2 |
|
|
225 |
30 |
|
|
|
|
516 |
541.4 |
566.8 |
592.2 |
617.6 |
|
225 |
35 |
|
|
|
|
538.5 |
563.9 |
589.3 |
614.7 |
640.1 |
|
225 |
40 |
|
|
|
|
561 |
586.4 |
611.8 |
637.2 |
662.6 |
|
225 |
45 |
|
|
|
|
583.5 |
608.9 |
634.3 |
659.7 |
685.1 |
|
225 |
50 |
|
|
|
|
606 |
631.4 |
656.8 |
682.2 |
707.6 |
|
225 |
55 |
|
|
|
|
628.5 |
653.9 |
679.3 |
704.7 |
730.1 |
|
225 |
60 |
|
|
|
|
651 |
676.4 |
701.8 |
727.2 |
752.6 |
|
225 |
65 |
|
|
|
|
673.5 |
698.9 |
724.3 |
749.7 |
775.1 |
|
235 |
30 |
|
|
|
|
|
547.4 |
572.8 |
598.2 |
623.6 |
|
235 |
35 |
|
|
|
|
|
570.9 |
596.3 |
621.7 |
647.1 |
|
235 |
40 |
|
|
|
|
|
594.4 |
619.8 |
645.2 |
670.6 |
|
235 |
45 |
|
|
|
|
|
617.9 |
643.3 |
668.7 |
694.1 |
|
235 |
50 |
|
|
|
|
|
641.4 |
666.8 |
692.2 |
717.6 |
|
235 |
55 |
|
|
|
|
|
664.9 |
690.3 |
715.7 |
741.1 |
|
235 |
60 |
|
|
|
|
|
688.4 |
713.8 |
739.2 |
764.6 |
|
235 |
65 |
|
|
|
|
|
711.9 |
737.3 |
762.7 |
788.1 |
|
245 |
30 |
|
|
|
|
|
553.4 |
578.8 |
604.2 |
629.6 |
655 |
245 |
35 |
|
|
|
|
|
577.9 |
603.3 |
628.7 |
654.1 |
679.5 |
245 |
40 |
|
|
|
|
|
602.4 |
627.8 |
653.2 |
678.6 |
704 |
245 |
45 |
|
|
|
|
|
626.9 |
652.3 |
677.7 |
703.1 |
728.5 |
245 |
50 |
|
|
|
|
|
651.4 |
676.8 |
702.2 |
727.6 |
753 |
255 |
30 |
|
|
|
|
|
559.4 |
584.8 |
610.2 |
635.6 |
661 |
255 |
35 |
|
|
|
|
|
584.9 |
610.3 |
635.7 |
661.1 |
686.5 |
255 |
40 |
|
|
|
|
|
610.4 |
635.8 |
661.2 |
686.6 |
712 |
255 |
45 |
|
|
|
|
|
635.9 |
661.3 |
686.7 |
712.1 |
737.5 |
255 |
50 |
|
|
|
|
|
661.4 |
686.8 |
712.2 |
737.6 |
763 |
265 |
30 |
|
|
|
|
|
|
590.8 |
616.2 |
641.6 |
667 |
265 |
35 |
|
|
|
|
|
|
617.3 |
642.7 |
668.1 |
693.5 |
265 |
40 |
|
|
|
|
|
|
643.8 |
669.2 |
694.6 |
720 |
265 |
45 |
|
|
|
|
|
|
670.3 |
695.7 |
721.1 |
746.5 |
265 |
50 |
|
|
|
|
|
|
696.8 |
722.2 |
747.6 |
773 |
275 |
30 |
|
|
|
|
|
|
596.8 |
622.2 |
647.6 |
673 |
275 |
35 |
|
|
|
|
|
|
624.3 |
649.7 |
675.1 |
700.5 |
275 |
40 |
|
|
|
|
|
|
651.8 |
677.2 |
702.6 |
728 |
275 |
45 |
|
|
|
|
|
|
679.3 |
704.7 |
730.1 |
755.5 |
275 |
50 |
|
|
|
|
|
|
706.8 |
732.2 |
757.6 |
783 |
285 |
30 |
|
|
|
|
|
|
602.8 |
628.2 |
653.6 |
679 |
285 |
35 |
|
|
|
|
|
|
631.3 |
656.7 |
682.1 |
707.5 |
285 |
40 |
|
|
|
|
|
|
659.8 |
685.2 |
710.6 |
736 |
285 |
45 |
|
|
|
|
|
|
688.3 |
713.7 |
739.1 |
764.5 |
285 |
50 |
|
|
|
|
|
|
716.8 |
742.2 |
767.6 |
793 |
295 |
30 |
|
|
|
|
|
|
608.8 |
|
|
685 |
295 |
35 |
|
|
|
|
|
|
638.3 |
|
|
714.5 |
295 |
40 |
|
|
|
|
|
|
667.8 |
|
|
744 |
295 |
45 |
|
|
|
|
|
|
697.3 |
|
|
773.5 |
295 |
50 |
|
|
|
|
|
|
726.8 |
|
|
803 |