Tyres

On the placard, usually on the driver's door pillar, sometimes inside the fuel or charging flap. It lists the size, the load index, the speed rating and the recommended pressures for normal and full loads. Use that rather than reading what is currently fitted, since a previous owner may have fitted something incorrect. If your vehicle offers more than one wheel size from the factory, the placard usually lists each option with its own pressures.

The load index is a coded number giving the maximum weight one tyre can carry at its rated pressure, and the speed rating is a letter giving the maximum sustained speed. Both must equal or exceed the vehicle manufacturer's specification. Fitting a lower load index on a heavy vehicle overloads the casing, which builds heat and risks failure, and it invalidates insurance in many markets. This matters particularly on battery electric vehicles, where the placard figure is often higher than the same body size would suggest.

Three reasons compound. The vehicle is heavier because of the battery, so each tyre carries more load. Torque arrives instantly and in full from a standstill, which shears the tread more than a gradual build up does. And the low rolling resistance compounds fitted to protect range trade tread life for efficiency. Reported wear rates run roughly twenty to thirty per cent higher than a comparable combustion car. Regular pressure checks and correct alignment make a measurable difference to that.

They are reinforced construction markings. XL, sometimes shown as extra load or RF, means the casing is built to carry more weight at a higher pressure than a standard tyre of the same size. HL, or high load, goes further and was introduced because heavy electric vehicles exceeded what XL could support at normal pressures. If your placard specifies one of these, fit it: a standard tyre of the same size is not equivalent, whatever the size marking suggests.

Find the four digit code at the end of the sidewall stamp: the first two digits are the week and the last two the year of manufacture. Rubber ages whether or not the tyre is used, hardening and cracking with heat and ultraviolet light, so a tyre with plenty of tread can still be past useful service. Inspect anything over five years old carefully, particularly on a vehicle that covers low mileage, and check the spare, which is often the oldest tyre on the car.

It maps directly onto a cause. Both shoulders worn with a healthy centre means the tyres have been run underinflated. A worn centre with good shoulders means overinflation. One shoulder alone worn is a camber or toe problem, so have the geometry measured before fitting new tyres or they will go the same way. Scalloped or cupped patches around the circumference point at damping that has stopped controlling the wheel. Fix the cause first, then buy the tyres.

Across an axle, always. Different tread depths or patterns on the same axle give unequal grip, which shows up under braking and in the wet. All four at once is only necessary on permanent four wheel drive vehicles, where significantly different rolling radii can load the driveline and, on some designs, cause real damage. On two wheel drive vehicles, replacing a pair is fine, and the newer pair conventionally goes on the rear axle for stability in the wet.

The range depends almost entirely on size, since a small diameter tyre and a large low profile one are very different products. The live minimum and maximum for the category are shown in the band at the top of this page. Because sizes move in and out of availability quickly, it is worth using the quote form even where a price is shown, to confirm current stock and the delivered figure before booking a fitting appointment.

Only with care and rarely with benefit. Changing section width, profile or rim diameter alters rolling radius, which affects the speedometer, the antilock calculations and the driver assistance systems that use wheel speed. It can also foul suspension components at full lock or compression. Where a manufacturer offers alternative sizes, they are listed on the placard with their own pressures. Outside those options, the placard size is the safe answer and the one that keeps everything else calibrated.

The figure on the placard, checked cold, not the maximum pressure moulded into the sidewall, which is a limit for the tyre rather than a recommendation for the vehicle. Most placards give a normal figure and a laden figure for full loads. Check monthly and before long journeys, since a tyre loses pressure slowly through the rubber itself, and remember that cold weather drops pressures measurably. Correct pressure is the cheapest thing you can do for wear, grip and range.

They are a genuine compromise rather than a marketing one, and whether the compromise suits you depends on the climate. In places where winter means occasional frost and rare snow, a good all season tyre with the three peak mountain snowflake marking avoids the cost and storage of a second set while giving far better cold weather grip than a summer tyre. Where winters bring sustained snow and ice, dedicated winter tyres remain considerably better and the two set approach is worth the trouble.

Yes, and quoting is a sensible route for tyres generally. Every reference here exists under its size and rating, and stock in a given size changes quickly. Press request a quote on the listing and a current figure comes back along with availability, so you can book the fitting appointment with confidence. Confirm the load index and speed rating in your request, since those are the details that must match the placard rather than merely the size.