Every tyre wears out, eventually and you will have to replace them, sooner or later. How a tyre wears out can tell you if there is something wrong with your car. Learning to read the early signs of trouble can prevent tyre wear that shortens tyre life or indicates the need for having other parts of the car serviced. So here are seven of the most common tread wear patterns and what causes them.
Centre wear can occur when your tyre is overinflated. It indicates that the air pressure in the tyre is consistently too high. When a tyre is overinflated, it bulges out more in the centre. The tyre then rides mostly on that bulge. This will wear your tyres along the centre and leave the edges untouched, as the bulge from overinflation keeps its edges off the ground. Keeping your tyres properly inflated can help prevent centre wear. If you aren’t sure what the proper tyre pressure is for you, consult your vehicle’s owner’s manual or look inside the driver’s doorjamb of the car where it should be listed.
This is the exact opposite of centre wear. The tyre will have a smooth, narrow strip of wear on one shoulder, a strip of normal-looking tread around the centre, then another smooth, narrow strip of wear on the other shoulder. This type of wear is usually a result of underinflation. When a tyre is underinflated, there is too much contact with the road by the outer treads, which wear prematurely. This could, however, also indicate a bent or worn-out steering component or the need for wheel alignment.
Camber wear causes the tyre to wear out on one side; but what is camber? Camber is the tilting angle of the wheel, when viewed from the front. When the wheels tilt outward at the top, the camber is positive. When the wheel tilts inward at the top, the camber is negative. If the camber is out of adjustment, it will cause wear on one side of the tyre. Too much positive camber will put too much load on the outside of the tyre and cause premature wear, while too much negative camber will wear out the inside of the tyre. The wheels may simply need to be aligned, but the misalignment could be due to sagging springs, worn ball joints or worn control arm bushings.
Cupped wear indicates that your suspension needs attention. Cupping occurs from repeated up and down motion, just like hopping. This might be caused by worn-out shock absorbers or struts that dampen the bouncing motion of the coil springs; or, for that matter, anything that connects the wheel to the rest of the car. When these suspension parts are worn out, they cause the tyre to bounce as it travels, coming down harder on some spots of the tyre than others. This can cause pieces of rubber to be gouged out of the tyre – this is called cupping. It looks like dips or bald spots in the tread. The solution: replace the worn-out components with new ones. Occasionally wheels that are out of balance will wear out like this – so remember to get them checked.
When you drive around corners at high speeds, the road essentially rubs against the tyre aggressively, resulting in feathered wear. While this can be spotted visually, it is usually easier to feel feathering when you run your hand along the tyre tread. The tread blocks will have rounded edges on one side and sharp edges on the other.
However, the more likely cause of feather wear is that the toe of your tyre is too far in or out – which can be fixed with proper wheel alignment. If the toe-in is set correctly and this wear pattern still occurs check for deteriorated bushings in the front suspension, causing the wheel alignment to shift as the car moves down the road.
‘FLAT SPOT’ WEAR
A single spot of heavy wear might show up on a tyre if the driver has braked hard and locked up the wheels in an emergency stop. The part of the tyre that was in contact with the road at that moment is scrubbed away by the excessive friction. A car without an Anti-Lock Braking System is more likely to have its tyres locked under heavy braking. This can cause a flat spot.
A flat spot can also develop if a car is kept parked for a long period of time. The weight of the car may deform the patch of tyre contacting the ground. Unlike flat spots resulting from a hard braking, these show no additional tread wear – nevertheless, the tyre is misshapen.
Toe is a measurement of how much the wheels are turned in or out from a straight-ahead position if you looked at it from above. When the wheels are angled inwards, toe is positive. When the wheels are angled outwards, toe is negative.
It is normal for a vehicle’s tyres to have a tiny amount of toe; but the toe can increase if the wheels are out of alignment, and this can cause Toe wear. Toe wear is typically seen on the inside shoulder of the tyre. Having your alignment checked and adjusted regularly can help you to avoid toe wear.
WHAT STEPS CAN YOU TAKE TO INCREASE YOUR TYRE’S LIFE?
Proper inflation: An improperly inflated tyre will wear more rapidly and unevenly. Not only do vehicle manufacturers specify the inflation pressures for the front and rear tyres to optimise performance for ride comfort, handling and fuel economy, they also take into consideration tyre wear. Proper inflation pressure helps optimise distribution of vehicle load, acceleration, braking, and cornering forces in the tread. So make sure that you check your tyre pressure regularly.
When you check your tyre pressure make sure that the tyres are cold. Manufacturers specify PSI or ‘pounds per square inch’ of pressure, assuming the tyres are cold. They are considered cold when the vehicle has been parked for three hours or more, or if the vehicle has been driven less than two kilometres at moderate speed.
Wheel alignment: Also known as tyre alignment refers to the adjustment of the vehicle’s steering and suspension components. The key to proper alignment is to adjust the angles of the tyres and their contact with the road in accordance with the vehicle manufacturer’s specifications for parameters such as camber and toe. Improper wheel alignment can cause your tyres to wear unevenly
Wheel balancing: Wheel imbalance can actually cause the tyre to lift off the road, causing steering and braking problems. An unbalanced wheel causes excessive mechanical wear and high fuel consumption, as well as tyre wear. Damage to the suspension, wheel bearings and steering components is unavoidable if the imbalance is left unattended. You must have your wheels balanced whenever you replace a tyre or have a puncture repaired.
TYRE PRESSURE GUIDELINES
- Carry out a tyre pressure check at least once a fortnight and before any long trips.
- Tyres must be cold when you carry out the check – preferably when they’ve been driven less than two kilometres.
- Get the right pressure reading from your vehicle manual, driver’s door ledge or fuel cap.
- Use a dependable gauge to measure the pressure.
- Remember to examine all of your tyres – not forgetting the spare.
- During your pressure check, give your tyre a visual check for tread wear or other common problems like cuts or bulges.
- Pressure decreases more rapidly in warmer weather, so make sure you check tyres frequently during summer.