TYRE INDEXING

Load Index:
The load index on a passenger-car tire was a numerical code stipulating the maximum load (mass, or weight) each tire could carry. For Load Range "B" tires, ETRTO (ISO-Metric) standards specify the load index rating at an inflation pressure of 36 psi (250 kPa) (table below), while P-Metric standards measure the load capacity at an inflation pressure of 35 psi (240 kPa). The two standards vary slightly with the capacity required for different inflation pressures.

Standard load table (extract from ETRTO standards manual – 2010 page G7
ref 42 psi (290 kPa))

Code	Weight		Code	Weight		Code	Weight		Code	Weight
60	250 kg (550 lb)		80	450 kg (990 lb)		100	800 kg (1,800 lb)		120	1,400 kg (3,100 lb)
61	257 kg (567 lb)		81	462 kg (1,019 lb)		101	825 kg (1,819 lb)		121	1,450 kg (3,200 lb)
62	265 kg (584 lb)		82	475 kg (1,047 lb)		102	850 kg (1,870 lb)		122	1,500 kg (3,300 lb)
63	272 kg (600 lb)		83	487 kg (1,074 lb)		103	875 kg (1,929 lb)		123	1,550 kg (3,420 lb)
64	280 kg (620 lb)		84	500 kg (1,100 lb)		104	900 kg (2,000 lb)		124	1,600 kg (3,500 lb)
65	290 kg (640 lb)		85	515 kg (1,135 lb)		105	925 kg (2,039 lb)		125	1,650 kg (3,640 lb)
66	300 kg (660 lb)		86	530 kg (1,170 lb)		106	950 kg (2,090 lb)		126	1,650 kg (3,638 lb)
67	307 kg (677 lb)		87	545 kg (1,202 lb)		107	975 kg (2,150 lb)		127	1,750 kg (3,858 lb)
68	315 kg (694 lb)		88	560 kg (1,230 lb)		108	1,000 kg (2,200 lb)		128	1,800 kg (3,968 lb)
69	325 kg (717 lb)		89	580 kg (1,280 lb)		109	1,030 kg (2,270 lb)		129	1,850 kg (4,079 lb)
70	335 kg (739 lb)		90	600 kg (1,300 lb)		110	1,060 kg (2,340 lb)		130	1,900 kg (4,189 lb)
71	345 kg (761 lb)		91	615 kg (1,356 lb)		111	1,090 kg (2,400 lb)		131	1,950 kg (4,289 lb)
72	355 kg (783 lb)		92	630 kg (1,390 lb)		112	1,120 kg (2,470 lb)		132	2,000 kg (4,409 lb)
73	365 kg (805 lb)		93	650 kg (1,430 lb)		113	1,150 kg (2,540 lb)		133	2,065 kg (4,541 lb)
74	375 kg (827 lb)		94	670 kg (1,480 lb)		114	1,180 kg (2,600 lb)		134	2,125 kg (4,674 lb)
75	387 kg (853 lb)		95	690 kg (1,520 lb)		115	1,215 kg (2,679 lb)		135	2,185 kg (4,806 lb)
76	400 kg (880 lb)		96	710 kg (1,570 lb)		116	1,250 kg (2,760 lb)		136	2,245 kg (4,938 lb)
77	412 kg (908 lb)		97	730 kg (1,610 lb)		117	1,285 kg (2,833 lb)		137	2,305 kg (5,071 lb)
78	425 kg (937 lb)		98	750 kg (1,650 lb)		118	1,320 kg (2,910 lb)		138	2,365 kg (5,203 lb)
79	437 kg (963 lb)		99	775 kg (1,709 lb)		119	1,360 kg (3,000 lb)		139	2,435 kg (5,357 lb)

Speed Rating:
The Speed rating of a tyre is the maximum speed at which the tyre could carry a load corresponding to its load index was an assigned letter ranging from J to Z that corresponds to the reference maximum speed at the associated load index. Refer to the speed rating table below.

CODE	mph	km/h		Code	mph	km/h
A1	3	5		L	75	120
A2	6	10		M	81	130
A3	9	15		N	87	140
A4	12	20		P	94	150
A5	16	25		Q	100	160
A6	19	30		R	106	170
A7	22	35		S	112	180
A8	25	40		T	118	190
B	31	50		U	124	200
C	37	60		H	130	210
D	40	65		V	149	240
E	43	70		Z	over 149	over 240
F	50	80		W	168	270
G	56	90		(W)	over 168	over 270
J	62	100		Y	186	300
K	68	110		(Y)	over 186	over 300

                            

						Examples The tires on a BMW Mini Cooper might be labeled: P195/55R16 85H P — these tires are for a passenger vehicle. However 'P' denotes P metric size load and speed rating changes for P tire & non-P tires. 195 — the nominal width of the tire is approximately 195 mm at the widest point 55 — indicates that the height of the sidewall of the tire is 55% of the width (107 mm) R — this was a radial tire 16 — this tire fits 16 in (410 mm) wheels 85 — the load index, a maximum of 515 kg (1,135 lb) per tire in this case H — the speed index, this means the maximum permitted speed, here 210 km/h (130 mph). The tires on a Hummer H1 might be labeled: 37X12.5R17LT 37 - the tire was 37 in (940 mm) in diameter 12.5 - the tire had a cross section of 12.5 in (320 mm) R - this was a radial tire 17 - this tire fits 17 in (430 mm) wheels LT - this was a light truck tire.