Tyre Maintenance: How to Make Your Tyres Last Longer

Your tyres are four patches of rubber each roughly the size of a hand, and every bit of acceleration, braking and steering the car does goes through them. Look after them and they last, grip properly and keep the car legal. Neglect them and they cost you money in fuel, in premature replacement, and occasionally in far worse ways.

Most of the work involved takes ten minutes a month.

How do you check tyre pressure correctly?

Check pressures when the tyres are cold, meaning the car has been standing for at least a couple of hours or has driven less than a couple of miles. Driving heats the air inside and raises the reading, so a hot check gives a falsely high figure and you end up running underinflated.

Where to find the correct figures:

• The placard on the driver's door shut or B pillar.
• Inside the fuel filler flap on many cars.
• The handbook.

Do not use the pressure moulded into the tyre sidewall. That figure is the maximum the tyre can take, not the pressure your car needs.

Most placards list two sets of figures: one for normal use with a couple of occupants, and one for a fully laden car. If you are loading up for a holiday, towing, or carrying a full car of passengers, use the laden figures. Coming back to normal pressures afterwards matters too, because a heavily overinflated tyre wears the centre out and loses grip.

Practical points:

• Buy a decent digital or dial gauge. Forecourt gauges take a hammering and are frequently well out.
• Check all four and the spare, which is the one everybody forgets until they need it.
• Refit the valve caps. They keep dirt and water out of the valve core.
• Recheck as the seasons change. Pressures fall as the weather cools, so a set adjusted in September can be noticeably soft by December.

Underinflation is the more common problem. It increases rolling resistance and fuel consumption, overheats the sidewalls, wears both shoulders of the tread, and increases the chance of a sudden failure at speed.

How much tread do your tyres need?

The UK legal minimum is 1.6mm across the central three quarters of the tread width, around the whole circumference. Anything less and the tyre is illegal, with a fine and penalty points applied to each offending tyre.

Every tyre also has tread wear indicators moulded into the bottom of the main grooves at 1.6mm. When the tread surface is level with those small raised bars, the tyre is at the legal limit and should already have been replaced.

The 20p test

The American penny test does not work here. Use a 20p coin instead:

• Push a 20p into one of the main tread grooves.
• If the raised outer band of the coin is completely hidden, you have a safe amount of tread, roughly 3mm or more.
• If any part of that band is visible, measure properly with a tread depth gauge.
• Repeat at three points around the circumference and at the inner, middle and outer part of the tread, because wear is rarely even.

Running down to exactly 1.6mm is legal but not sensible. Wet braking distances and resistance to aquaplaning fall away sharply below about 3mm, which is why many tyre manufacturers and road safety organisations recommend replacing at that point rather than waiting for the limit.

What do uneven tyre wear patterns tell you?

Wear patterns are diagnostic. Read them and you find the underlying fault before it eats another set of tyres.

If you find any of these, replacing the tyre without fixing the cause just means doing it again.

Wheel alignment, balancing and rotation

Alignment (often called tracking) sets the angles at which the wheels meet the road. Kerbs and potholes knock it out, and UK road surfaces provide plenty of both. Symptoms are the car pulling to one side, a steering wheel that is not straight when the car is, or uneven wear on the front tyres. Have it checked after any significant impact, when fitting new tyres, and every year or two as routine.

Balancing corrects weight distribution around the wheel and tyre assembly. An out of balance wheel shows up as a vibration through the steering at a particular speed, usually somewhere between 50 and 70mph, that comes and goes as the speed changes. Wheels are balanced when tyres are fitted, but weights fall off and tyres wear unevenly, so a rebalance is often the cure for a vibration that appeared without warning.

Rotation used to be standard advice, and for a car with four identical tyres it still evens out wear. Check first, though, because it does not apply to every car:

• Many performance and premium cars have staggered fitments, with wider tyres on the rear, which cannot be swapped front to rear.
• Directional tyres must stay on the same side unless they are removed from the rim and refitted.
• Some manufacturers no longer recommend rotation at all. Check the handbook.

Where rotation is possible, front to rear on the same side is the simplest pattern for directional tyres, and a crossed pattern for non directional ones.

Potholes, kerbs and speed bumps

Impact damage is the biggest single cause of tyre and wheel problems on UK roads. A pothole hit at speed pinches the sidewall between the road edge and the rim, which can cause an immediate blowout or leave an internal weakness that fails days later.

Reduce the damage:

• Slow down for speed bumps and take them square rather than at an angle.
• If you cannot avoid a pothole, brake before it rather than through it, and let the wheel roll into it with the steering straight.
• Keep pressures correct, because an underinflated tyre offers far less cushion between road and rim.
• Give yourself room from the kerb when parking. Most kerbing happens on tight parallel parks.

After a heavy impact, check:

• A bulge or blister in the sidewall. This is a broken carcass cord. The tyre must be replaced and cannot be repaired.
• Cuts, cracks or exposed cords anywhere on the tyre.
• The wheel rim itself for flat spots, buckles or hairline cracks, particularly on the inner rim edge where you cannot see it without removing the wheel.
• Steering and tracking, if the car pulls or the wheel sits off centre afterwards.

A buckled or cracked rim usually shows up as a tyre that keeps going soft with no puncture to be found, or a vibration that will not balance out. Both are fixable. Signature straightens and refinishes damaged wheels through our alloy wheel repair service, and factory finished wheels with the machined face can be restored with mobile diamond cut wheel repair rather than replaced.

When can a tyre be repaired?

A puncture repair has to meet the British Standard for tyre repairs, BS AU 159. In practical terms a tyre can normally be repaired when:

• The damage is within the central three quarters of the tread width, known as the minor repair area.
• The hole is no more than 6mm across.
• The tyre has not been driven on while flat, which destroys the inner liner.
• There is no existing repair too close to the new one, and enough tread left to justify the work.

A tyre cannot be safely repaired if the damage is in the shoulder or sidewall, if there is a bulge, if the cords are exposed, or if the internal inspection shows the liner has broken up. A proper repair means removing the tyre from the rim and inspecting it inside, then fitting a combined plug and patch. External string repairs and aerosol sealant are temporary get you home measures, not repairs.

Run flat tyres are a separate case. Most manufacturers do not permit repair of a run flat that has been driven on while deflated, because there is no reliable way to tell how far it went.

Reading the sidewall markings

Everything you need to buy the right replacement is written on the tyre.

Load index and speed rating must at least match what the manufacturer specifies. Fitting a lower rating is both unsafe and something an insurer can take issue with.

Choosing tyres for UK conditions

Buy on the label and the specification rather than on the name alone. The UK tyre label shows fuel efficiency, wet grip and noise, all graded, and wet grip is the one worth paying for on British roads.

• Summer tyres give the best dry and wet performance in mild conditions and are what most cars come on.
• Winter tyres use a softer compound that stays flexible in the cold and a tread with far more sipes. They are worth having if you drive through winter in hilly or rural areas, and they work below about 7 degrees whether or not there is snow.
• All season tyres carrying the three peak mountain snowflake mark are a reasonable compromise for most UK drivers, giving useful cold weather performance without a second set of wheels.

Budget tyres are not automatically a bad choice, but the gap between a budget and a premium tyre shows up most in wet braking distance, which is exactly where you want the margin. Compare wet grip grades before deciding on price.

Never mix construction types on the same axle, and it is illegal in the UK to mix radial and cross ply on the same axle or to fit cross ply to the rear with radial on the front. Keep the same make, pattern and rating across each axle wherever you can.

Storage, valves and the spare

If you swap between summer and winter sets, store the spare set clean, dry, out of direct sunlight, away from solvents and away from anything producing ozone such as an electric motor. Store them upright and rotate their position occasionally if they are mounted on wheels, or stacked flat if they are loose tyres.

Replace valves whenever you fit new tyres. Rubber valves perish and metal valve stems on alloy wheels corrode where dissimilar metals meet, which is a slow leak waiting to happen. If the car has direct TPMS sensors, use the service kit with new seals, nut and core each time the tyre is changed.

Check the spare every few months. A space saver spare has its own inflation pressure, usually much higher than a normal tyre, and comes with a speed and distance limit that is printed on the wheel. If your car has a sealant kit instead of a spare, note the expiry date on the bottle, because the sealant does have a shelf life.

Keeping tyres clean without damaging them

Wash tyres with car shampoo and a stiff brush rather than harsh solvents. Strong acidic wheel cleaners left to dry can attack both the tyre sidewall and the lacquer on an alloy wheel, and a silicone heavy tyre dressing that slings onto the paintwork is a nuisance to remove.

The practical benefit of cleaning them is not appearance. It is that you get down at wheel level once a fortnight and actually look at all four tyres, which is when you spot the nail, the cut, the bulge or the wear pattern that would otherwise become a problem on a wet motorway.

If cleaning reveals kerb rash, lacquer peel or corrosion on the wheels themselves, that is our end of the job rather than a tyre fitter's, and a free quote takes 24 hours from a couple of photographs.