174:
102:, display what would now be recognised as the classic bar grip pattern of sharp-edged transverse bars with a wide central rib. However these were supplied for narrow high-pressure tyres, for use on roads and at relatively high speeds. Their design was based on simple notions of transverse bars giving fore-and-aft traction, without any developed theory of tread design or experimental measurements of their performance. In practice, such square-edged tread blocks wore badly and unevenly, the initially flat blocks tending to wear with a sloping top surface. This wear pattern was one reason for the practicing of rotating tyres between wheels, so that they spent equal periods wearing in each direction.
129:
crosswise bars and large gaps between. This helical pattern also gave rise to a sideways force, particularly on tarmac. As all tyres had the same 'hand', this force increased across the two sides of the vehicle. To counteract this force, the central stop-rib was added. The stop-rib was only partly successful though; snowy conditions led the Swiss Post Office to use left- and right-handed tyres to balance the force across the vehicle. Later developments would use balanced arrangements of ribs in a chevron or herringbone layout. The more common arrangement for the later low-speed military bar grip was to use straight bars, but relying on the centre rib to avoid their vibration problems on tarmac.
118:
109:'Traction' tread pattern of 1922 and the 'Triple stud' pattern of 1927. These followed the same principle of a solid central rib with square-edged blocks, but were developed to improve tread wear. The central rib became a thin and almost vestigial rib between square blocks. The side blocks were now isolated from the centre, although linked by another narrow rib, and their leading and trailing edges formed a trapezium rather than a square. This triple square stud pattern was a successful pattern for narrow tyres, including motorcycles, and remained popular from several manufacturers into the 1950s.
17:
65:
963:
953:
192:
The usual military replacement for a bar grip tyre today is now a pattern like the
Michelin XCL or 'NATO Pattern'. This consists of large solid rubber blocks, of similar size to the bar grip bars. These blocks are arranged in crosswise bars of three blocks, so that there is now good water clearance
164:
The poor water clearance of bar grips may limit their performance on very wet mud. With later patterns, such as the NATO, water may be squeezed out from between the blocks, leaving the mud drier and firmer. As the bar grip gives no escape for this water, they may retain a layer of water-lubricated
128:
The first deliberate uses of bar grip tyres as off-road tyres, were developed pre-war as truck tyres particularly for army use. They used crosswise tread bars for grip, arranged in a helical pattern. A helical pattern was used to avoid the uneven rolling radius and vibration of a tread with simple
184:
Bar grips were replaced on light vehicles such as Land Rovers and Jeeps in the 1970s, although they remained on heavy trucks. This was due to the faster speeds likely for light vehicles and the bar grip's poor tarmac performance. Developments in tyres, particularly the development of
193:
between blocks, both radially and axially. As the blocks are still large though and unsiped, water clearance from the block surface is still poor and the tyres still have a risk of aquaplaning on wet tarmac, compared to a typical road tyre. This pattern is also
80:
Deliberate shaping of moulded tyre tread design, rather than merely concentrating on a rubber surface that didn't fail rapidly, began at the start of the 1920s. There was little theoretical background to this though until the mid-1920s. The 1922 London
44:
Bar grips are characterised by a solid rubber circumferential centre strip, with large solid cleat alternately to either side. These span the full width of the tread. It is characteristic of this pattern that they do not have any tread pattern or
148:
Although the bar grip performs well as a pattern for severe mud, and is acceptable for most off-road surfaces, its lack of a small tread pattern makes it poor at clearing water. They are thus highly prone to
160:
The small footprint of the bar grip tread makes them perform poorly on sand. Even in the 1930s, 'balloon' tyres with wider treads, smaller tread patterns and lower pressures, were available for desert use.
136:, having been developed when this was the only practical means of manufacturing tyres. The simple pattern of bar grips also made them easy to manufacture and hard-wearing, even if made from poor quality or
56:
to heavy trucks and armoured cars. They fell from favour in the 1970s and largely disappeared by the 1990s, having been replaced by newer patterns with better all-around performance.
194:
895:
92:
52:
Bar grip tyres were developed in the 1930s and were the standard military pattern throughout World War II, for vehicles from
298:
97:
82:
794:
390:
784:
653:
905:
425:
992:
683:
915:
887:
746:
703:
633:
173:
842:
761:
713:
708:
290:
282:
829:
615:
560:
728:
693:
673:
8:
799:
435:
407:
383:
157:
well, but their large area of smooth unbroken rubber makes them poor performers on ice.
837:
668:
263:
87:
952:
663:
540:
475:
294:
117:
956:
769:
718:
628:
550:
530:
490:
480:
460:
231:
68:
698:
658:
648:
643:
583:
525:
186:
46:
360:
189:, also permitted a multi-purpose tyre that performed well both on and off-road.
987:
966:
877:
867:
857:
603:
495:
376:
133:
981:
774:
741:
638:
623:
470:
430:
415:
121:
30:
tyres, or 'NDT' (Non-Directional Tire) in US military parlance, are an early
900:
814:
809:
779:
688:
598:
593:
535:
515:
510:
440:
106:
64:
16:
928:
852:
804:
789:
736:
505:
485:
420:
211:
150:
933:
751:
678:
588:
578:
545:
249:
177:
154:
153:
on wet tarmac or smooth surfaces. They perform well on snow and carry
34:
20:
923:
872:
862:
819:
568:
520:
455:
450:
500:
573:
197:
and so wheels should be mounted as either left-side or right-side.
38:
847:
206:
140:
rubber, bulked up with extreme quantities of non-rubber fillers.
137:
445:
234:
for a similar solution to axial thrust in gear transmissions.
85:
displayed a range of tread patterns that were reported on by
938:
399:
314:
312:
310:
53:
31:
368:
307:
324:
276:
274:
165:
mud like quicksand that remains extremely slippery.
91:. Some of these, from Miller and the French firm of
271:
979:
384:
896:European Tyre and Rim Technical Organisation
342:
391:
377:
349:The huge tyres now made – we used 10.50×16
330:
318:
280:
172:
116:
63:
15:
980:
75:
372:
105:Later, and better, patterns were the
347:. London: Collins. pp. 12, 17.
124:on late bar grips, with helical skew
49:cut into the rubber to clear water.
939:Uniform Tire Quality Grading (UTQG)
289:. Dunlop Archive Project. pp.
283:"9: The Beginnings of Tyre Science"
13:
14:
1004:
287:The History of the Pneumatic Tyre
962:
961:
951:
795:Tire-pressure monitoring system
112:
354:
336:
254:
243:
224:
168:
59:
1:
785:Central Tire Inflation System
217:
143:
7:
906:Tire Science and Technology
426:Low rolling resistance tire
343:Kennedy Shaw, W.B. (1945).
200:
10:
1009:
947:
914:
886:
828:
760:
727:
614:
559:
406:
398:
23:Jeep with bar grip tyres
747:Slip (vehicle dynamics)
704:Lateral Force Variation
654:Pacejka's Magic Formula
634:Cold inflation pressure
345:Long Range Desert Group
281:Tompkins, Eric (1981).
843:List of tire companies
714:Traction (engineering)
709:Radial Force Variation
181:
125:
72:
71:on staggered bar grips
24:
694:Tire load sensitivity
176:
120:
67:
19:
674:Self aligning torque
180:on XCL pattern tyres
800:Tire-pressure gauge
436:Michelin PAX System
76:Early road patterns
838:Tire manufacturing
669:Rolling resistance
261:"The Motor Show".
182:
132:All bar grips are
126:
73:
25:
993:Off-road vehicles
975:
974:
664:Relaxation length
541:Formula One tyres
321:, pp. 72–73.
1000:
965:
964:
957:Outline of tires
955:
770:Tire maintenance
719:Treadwear rating
629:Circle of forces
551:Continental tire
491:Orange oil tires
481:Mud-terrain tire
461:All-terrain tire
393:
386:
379:
370:
369:
363:
358:
352:
351:
340:
334:
328:
322:
316:
305:
304:
278:
269:
268:
258:
252:
250:Wheels and Tires
247:
235:
232:Herringbone gear
228:
187:radial-ply tyres
101:
69:Scammell Pioneer
1008:
1007:
1003:
1002:
1001:
999:
998:
997:
978:
977:
976:
971:
943:
910:
882:
824:
756:
723:
699:Tire uniformity
659:Pneumatic trail
649:Ground pressure
644:Cornering force
610:
584:Siping (rubber)
555:
526:Motorcycle tyre
402:
397:
367:
366:
359:
355:
341:
337:
331:Tompkins (1981)
329:
325:
319:Tompkins (1981)
317:
308:
301:
279:
272:
260:
259:
255:
248:
244:
239:
238:
229:
225:
220:
203:
171:
146:
115:
95:
78:
62:
12:
11:
5:
1006:
996:
995:
990:
973:
972:
970:
969:
959:
948:
945:
944:
942:
941:
936:
931:
926:
920:
918:
916:Identification
912:
911:
909:
908:
903:
898:
892:
890:
884:
883:
881:
880:
878:Ozone cracking
875:
870:
865:
860:
858:Tire recycling
855:
850:
845:
840:
834:
832:
826:
825:
823:
822:
817:
812:
807:
802:
797:
792:
787:
782:
777:
772:
766:
764:
758:
757:
755:
754:
749:
744:
739:
733:
731:
725:
724:
722:
721:
716:
711:
706:
701:
696:
691:
686:
684:Steering ratio
681:
676:
671:
666:
661:
656:
651:
646:
641:
636:
631:
626:
620:
618:
612:
611:
609:
608:
607:
606:
604:Schrader valve
601:
596:
586:
581:
576:
571:
565:
563:
557:
556:
554:
553:
548:
543:
538:
533:
528:
523:
518:
513:
508:
503:
498:
496:Whitewall tire
493:
488:
483:
478:
473:
468:
463:
458:
453:
448:
443:
438:
433:
428:
423:
418:
412:
410:
404:
403:
396:
395:
388:
381:
373:
365:
364:
353:
335:
323:
306:
299:
270:
267:. Autumn 1922.
253:
241:
240:
237:
236:
222:
221:
219:
216:
215:
214:
209:
202:
199:
170:
167:
145:
142:
114:
111:
77:
74:
61:
58:
37:developed for
9:
6:
4:
3:
2:
1005:
994:
991:
989:
986:
985:
983:
968:
960:
958:
954:
950:
949:
946:
940:
937:
935:
932:
930:
927:
925:
922:
921:
919:
917:
913:
907:
904:
902:
899:
897:
894:
893:
891:
889:
888:Organizations
885:
879:
876:
874:
871:
869:
866:
864:
861:
859:
856:
854:
851:
849:
846:
844:
841:
839:
836:
835:
833:
831:
827:
821:
818:
816:
813:
811:
808:
806:
803:
801:
798:
796:
793:
791:
788:
786:
783:
781:
778:
776:
775:Tire rotation
773:
771:
768:
767:
765:
763:
759:
753:
750:
748:
745:
743:
742:Groove wander
740:
738:
735:
734:
732:
730:
726:
720:
717:
715:
712:
710:
707:
705:
702:
700:
697:
695:
692:
690:
687:
685:
682:
680:
677:
675:
672:
670:
667:
665:
662:
660:
657:
655:
652:
650:
647:
645:
642:
640:
639:Contact patch
637:
635:
632:
630:
627:
625:
624:Camber thrust
622:
621:
619:
617:
613:
605:
602:
600:
597:
595:
592:
591:
590:
587:
585:
582:
580:
577:
575:
572:
570:
567:
566:
564:
562:
558:
552:
549:
547:
544:
542:
539:
537:
534:
532:
529:
527:
524:
522:
519:
517:
514:
512:
509:
507:
504:
502:
501:Aircraft tire
499:
497:
494:
492:
489:
487:
484:
482:
479:
477:
474:
472:
469:
467:
464:
462:
459:
457:
454:
452:
449:
447:
444:
442:
439:
437:
434:
432:
431:Run-flat tire
429:
427:
424:
422:
419:
417:
416:Tubeless tire
414:
413:
411:
409:
405:
401:
394:
389:
387:
382:
380:
375:
374:
371:
362:
357:
350:
346:
339:
333:, p. 74.
332:
327:
320:
315:
313:
311:
302:
300:0-903214-14-8
296:
292:
288:
284:
277:
275:
266:
265:
257:
251:
246:
242:
233:
227:
223:
213:
210:
208:
205:
204:
198:
196:
190:
188:
179:
175:
166:
162:
158:
156:
152:
141:
139:
135:
130:
123:
122:Alvis Saracen
119:
110:
108:
103:
99:
94:
90:
89:
84:
70:
66:
57:
55:
50:
48:
42:
40:
36:
35:tread pattern
33:
29:
22:
18:
901:Tire Society
815:Tire changer
810:Bead breaker
780:Bicycle pump
689:Tire balance
599:Presta valve
594:Dunlop valve
536:Racing slick
531:Tractor tire
516:Tubular tire
511:Bicycle tire
465:
441:Airless tire
361:Tire Choices
356:
348:
344:
338:
326:
286:
262:
256:
245:
226:
191:
183:
163:
159:
147:
131:
127:
113:Off road use
104:
86:
79:
51:
43:
27:
26:
929:Plus sizing
853:Waste tires
805:Direct TPMS
790:Tire mousse
762:Maintenance
737:Aquaplaning
506:Tundra tire
486:Paddle tire
471:Knobby tire
421:Radial tire
264:The Autocar
212:Paddle tire
195:directional
169:Replacement
151:aquaplaning
96: [
88:The Autocar
60:Development
982:Categories
934:Tire label
830:Life cycle
752:Tramlining
679:Slip angle
616:Attributes
589:Valve stem
561:Components
546:Spare tire
476:Large tire
218:References
178:Land Rover
134:crossplies
93:Bergougnan
83:Motor Show
21:Willys M38
924:Tire code
873:Flat tire
863:Tire fire
820:Tire iron
729:Behaviors
521:Lego tire
456:Snow tire
451:Rain tyre
144:Drawbacks
967:Category
574:Beadlock
466:Bar grip
201:See also
39:off-road
28:Bar grip
868:Blowout
848:Retread
207:Grouser
297:
155:chains
138:ersatz
107:Dunlop
988:Tires
579:Tread
446:Tweel
408:Types
400:Tires
100:]
54:Jeeps
47:sipes
41:use.
569:Bead
295:ISBN
230:See
32:tyre
984::
309:^
293:.
291:56
285:.
273:^
98:fr
392:e
385:t
378:v
303:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
.jpg)
