WORSE FOR WEAR
WORSE FOR WEAR
A few months ago, we were speaking about tyre failures and their common causes. Since then, we’ve had a number of queries about irregular tread wear, and what causes it. But before we get started on diagnosing your tyre issues, let’s first consider who the suspects are…
- The tyre
- Your vehicle
No-one likes criticism, so we’re going to skip the first one and assume that you’re a sensible driver who frequently rotates, balances, and checks tyre pressures.
This brings us to the tyre itself. Believe it to not, tyre manufacturers rely heavily on repeat business and word-of-mouth marketing, which means that inferior products almost never last long on the market.
So where does that leave us? Well, if the problem (or wear pattern) can be seen on more than one tyre, it’s generally a dead giveaway that your vehicle’s suspension, steering, and/or chassis components are to blame. The question is, how do you know which part is the problem?
Every vehicle is different, because every vehicle is driven differently. So unfortunately, there are no hard and fast rules such as: if this wears like that, then this is to blame. However, we can make some generalisations as to which mechanical components commonly have an ill effect on your tyres. Here they are…
WORN TIE-ROD ENDS
Aside from poor tyre balancing, alignment, and inflation, one of the most common causes of rapid (front) tyre wear is through worn tie-rod ends. Similarly, a bent steering arm, track bar, or damaged tie-rod can cause misalignment in the steering system and lead to excessive tyre wear. However, the problem is usually just age-related wear within the tie-rod.
If you lie under your vehicle while someone rocks the steering wheel back and forth, you’ll quickly see signs of vertical or horizontal play within your 4x4’s inner and outer tie-rods if they’re worn. If play is evident within the joint, there’s a good chance that it needs replacing.
You can perform the same test for your 4x4’s steering system. Have someone rock the steering wheel back and forth while you check the system for excessive play in the linkages, steering column, and mounting bolts. (These can work their way loose over time). Make sure that the full weight of the vehicle is on the front tyres while performing this test, and use a marker (or Tipex pen) to mark the areas where you see play.
Over time, your 4x4’s suspension may show signs of sagging – leading to a reduction in ride height and changes in the vehicle’s caster and camber angles (alignment). When this happens, a new suspension system should be fitted; alternatively, the springs should be shimmed to restore the vehicle’s factory-specified ride height.
SHOCK ABSORBERS / STRUTS
Another VERY common cause of premature or irregular tyre wear. Shock absorbers are designed to keep your tyres in contact with the road. If your shocks are worn, this will lead to tyre bounce, which typically leads to “cupping” or uneven circular tread wear. In terms of driving performance, tyres that are “cupped” will usually ride with a lot of vibration and noise.
If a bump in the road causes steering shudder, there’s a good chance that your shocks are worn. You should also visually inspect your shocks for fluid leakage, or any signs of damage – a bent rod or dented housing.
CONTROL ARM BUSHES
Bushes don’t last forever, especially when they endure a lot of load and movement. This is particularly true for control-arm bushes, which can have a significant effect on camber alignment when worn.
Control arms are designed to centralise the axle, and to prevent shifting or rotating of the axle when torque is applied. If your control arm bushes are worn, your axle may pivot in place, or may also show signs of shifting backwards and forwards.
Of course, the most common cause of excessive tyre wear is poor upkeep. This generally relates to tyre pressure and the fact that most people fail to check their tyre pressures regularly. Or, they load their vehicle and forget to increase their tyre pressures accordingly. You should check your tyre pressures (when cold) at least once a month, and ideally, every time you fill up with fuel. Things like balancing, alignment and rotation are also vitally important when it comes to getting the most out of your tyres.
All of the above points are common causes of irregular (and premature) tyre wear, but before you jump to conclusions and start buying new (expensive) suspension components, you may want to start your diagnosis with the following list of most likely tyre-wear causes, in their respective order:
- Incorrect tyre pressure
- Lack of tyre balancing
- Lack of tyre rotation
- Lack of wheel alignment
- Incorrect tyre fitment / bead seating
- Bad driving habits – such as aggressive driving
- Budget tyres – cheap tyre compounds seldom last long
- Excessive suspension modifications that are poorly set up
- Worn shock absorbers
- Worn tie-rod ends
- Worn steering components
- Worn or sagging suspension