They're round, black and made of rubber. Tyres. Not the most exciting part of a car, are they? Tyres are a vital component of your vehicle however, and have a big influence on its performance.

Your tyres have to transmit all of the cars driving, steering and braking force to the road surface through four contact areas, each approximately that of a size 10 men's shoe; on all types of surfaces and in varying weather conditions.

That little bit of rubber has to do an awful lot.

You’re travelling along the highway at 100klm/hr and your engine seizes, your windscreen wipers stop or your battery dies? What happens? Generally speaking, not much. You slow down, pull over and sort the problem. And when your tyre blows out?

It can mean Game Over for you and your passengers, and anyone else who gets in the way.

So what’s riding on your tyres? More importantly, who? Please take a moment to view some of the information we have provided in this section and make sure you are making the best decisions when it comes to round, black rubber.

Tyres are high technology items that have been continually refined and improved by over 100 years of research and development. The wheel and indeed the tyre have been improved upon and these days we are riding on a great deal more than rubber, as the diagram below shows...



MAINTENANCE

Continuing to use worn, damaged or simply the wrong tyres can literally mean the difference between life and death.

A set of new tyres on your car can cost upwards of $400 so it's well worthwhile looking after them. Regular checking is vital - if you don't catch a leaking tyre early it could be ruined in no time at all. Some things to consider:

Tyre pressure – check this every 2 weeks and use a reliable pressure gauge (check them when they are cold). Make sure you maintain the recommended pressure at all times. Around 80% of passenger car tyres run with some degree of under-inflation and this affects tyre longevity, passenger safety and fuel consumption

Tread – the minimum legal tread depth in Australia is 1.6mm. This is the minimum depth and it is worth noting that your stopping distance in wet weather may increase up to 70%, compared with a new tyre. To ensure long life and even tread wear, rotate your tyres at every service, or at least every 6 months. Front tyres on a front wheel drive car wear 2 ½ times faster than the rear tyres so it is even more important to do this. Once uneven tread wear has set in, it is impossible to stop.

Load - Utes, panel vans and 4WDs - check the tyre pressure is right for your load. Check the tyre placard and /or the owner’s manual for the correct pressure for the load.

Ouch - Avoid scuffing and hitting kerbs when parking your vehicle.

Valve cap - Make sure all your tyres have a valve cap, as it is the main seal.

In Australia, the only markings required on a tyre sidewall are as follows:

• Manufacturers Logo or brand name
• Tyre Size, Series, Rim Size, Load and Speed Rating/Symbol
• Serial No. - date code (when tyre was built; week, month, year)
• Details of construction showing tyre size, radial, tubeless or tubed
• Country of Origin
• Mould Number
• Factory code number

On the sidewall of a tyre you will notice a number codes and markings which relate to its various features. As an example, a tyre could have the code P205/65 R16 95 V printed on the side wall, and this is broken down as follows:



P - type of vehicle the tyre was made for (P=Passenger, C=Commercial, LT=Light Truck)
205 - section width of the tyre in millimeters
65 - height of the sidewall described as a percentage of the section width. Larger numbers mean a more comfortable ride. Smaller numbers mean better performance but a harder ride.
R - radial ply construction (steel belts running across the tyre from lip to lip). 98% of tyres today are of radial ply construction as they deliver greater stability, less wear and better fuel economy
16 - diameter of the wheel rim in inches
95 - load index. The maximum load capacity of the tyre. 95 equates to 690kg (please refer to "Load Index & Speed Rating" below)
V - speed rating. Indicates the maximum speed at which the tyre can carry its rated load. V equates to 240klm/h (please refer to “Load Index & Speed Rating" below)

Load Index & Speed Rating
Reference tables and further information can be found in the “Tyres – Load Index & Speed Rating” section (select from Top).

Tyre Age
Tyres carry a three digit code on the sidewall indicating the month & year of manufacture. For example; 129 means the tyre was manufactured in December 1999.

Other Markings
M&S - mud and snow tyres
DOT codes - (denotes US Dept. Of Transport codes; place of manufacture etc)
E-marks - (European Community codes)
UTQGS - Uniform Tyre Quality Grading System; a system that covers grade markings for tread wear, traction performance & temperature resistance on all tyres manufactured & sold in the US. This system may be shown on tyres sold in Australia and may be "helpful" when buying tyres in Australia, however it cannot be taken as a safety rating or guarantee as to how well a tyre will perform on Australian roads as they are based on tests carried out in the US under very specific conditions for that specific market.

For further information, please speak directly with your professional tyre retailer.

The Load Index is an assigned number ranging from 0 to 279 that corresponds with the maximum load carrying capacity of a tyre. Most passenger car tyre load indexes range from 62 to 126.

The Speed Index is an assigned letter ranging from J to Z that corresponds to the reference maximum speed at the associated load index.

These two elements put together are called the Service Description and are mutually dependent (one takes into account the other).

The table below gives the load index and the speed symbol with their corresponding values

Load Index	Load per tyre (kg)	Load Index	Load per tyre (kg)	Load Index	Load per tyre (kg)	Load Index	Load per tyre (kg)	Load Index	Load per tyre (kg)	Speed Symbol	Speed (klm/h)
62	265	75	387	88	560	101	825	114	1180	J	100
63	272	76	400	89	580	102	850	115	1215	K	110
64	280	77	412	90	600	103	875	116	1250	L	120
65	290	78	425	91	615	104	900	117	1285	M	130
66	300	79	437	92	630	105	925	118	1320	N	140
67	307	80	450	93	650	106	950	119	1360	P	150
68	315	81	462	94	670	107	975	120	1400	Q	160
69	325	82	475	95	690	108	1000	121	1450	R	170
70	335	83	487	96	710	109	1030	122	1500	S	180
71	345	84	500	97	730	110	1060	123	1550	T	190
72	355	85	515	98	750	111	1090	124	1600	H	210
73	365	86	530	99	775	112	1120	125	1650	V	240
74	375	87	545	100	800	113	1150	126	1700	W	270
										Y	300
										VR	>210