What does tyre size mean?

To the untrained eye, the side wall of a tyre can look like a meaningless set of numbers, letters and symbols. Hidden amongst these is the tyre size. But what does it look like and, more importantly, what does it mean?

How the tyre size might appear.

Dissecting the code

The tyre size might read like this: P195/55 R16 87 V. Hardly user friendly but, when you know what it all means, you’ll realise it tells you useful information about the tyre’s construction, size and type.

1 Cross section width

The first three numbers, in this case 195, refer to the section width of the tyre. This is the measurement, in millimetres, from the tyre’s inner sidewall to its outer sidewall.

2 Aspect ratio

The aspect ratio, or profile, refers to the height of the sidewall as a % of the section width. In our example, 55 means the height is equal to 55% of the 195mm width. The bigger the aspect ratio, the bigger the sidewall will be.

3 Construction type

The letter R means the tyre is a radial construction. Almost all new car tyres are radials.

4 Rim

The number to the right of the construction type is the rim diameter, measured in inches. In this case, it’s a 16” wheel.

5 Load index

The final number is the load index i.e. the maximum load (in kg) that the tyre can carry. See chart below

Load Index	Load in kg	Load Index	Load in kg	Load Index	Load in kg	Load Index	Load in kg
62	265	79	437	96	710	113	1150
63	272	80	450	97	730	114	1180
64	280	81	462	98	750	115	1215
65	290	82	475	99	775	116	1250
66	300	83	487	100	800	117	1285
67	307	84	500	101	825	118	1320
68	315	85	515	102	850	119	1360
69	325	86	530	103	875	120	1400
70	335	87	545	104	900	121	1450
71	345	88	560	105	925	122	1500
72	355	89	580	106	950	123	1550
73	365	90	600	107	975	124	1600
74	375	91	615	108	1000	125	1650
75	387	92	630	109	1030	126	1700
76	400	93	650	110	1060
77	412	94	670	111	1090
78	425	95	690	112	1120

Tyre load rating table

6 Speed symbol

The final character (in this case V) relates to the maximum speed of use. Again, the following table will clarify what your tyre’s symbol means.

Speed Rating	Mile/Hour	Kilometers/Hour	Speed Rating	Mile/Hour	Kilometers/Hour
N	87	140	U	124	200
P	93	150	H	130	210
Q	99	160	V	149	240
R	106	170	ZR	150+	240+
S	112	180	W	168	270
T	118	190	Y	186	300

Tyre speed rating table

Where can I find my car’s tyre size?

You’ll find you car’s tyre size on the tyres’ sidewall, in your car’s vehicle manual as well as on a sticker inside the driver’s door. If you’re still unsure, visit your nearest Uniroyal dealership for advice.

Uniroyal. A brand of Continental.*