As a motorist you probably know that your car tyres are subject to wear and have to be periodically replaced to keep you safe and within the law. Tyre wear depends upon a number of factors including tyre composition, the surface that they are being used on and the condition of the car. But not all wear is the same and it is worth knowing that some types can be more damaging to your car tyres than others.

Your tyres are the only contact that your vehicle has with the road. Made of reinforced rubber, they allow traction and the delivery of power safely, but are a consumable product that gradually wears down. 

What is saw tooth tyre wear?

If a tyre is inflated correctly, the wear should be fairly even across it. If, however, it wears more at the edges, then the tyre is likely to be underinflated, and over inflated if it wears more in the middle section. Saw tooth tyre wear, also known as tyre stepping, is another uneven tyre wear pattern.

Tyres have distinctive tread patterns moulded into their surface to allow them to get extra grip on the road. Their tread gives them the ability to deal with all surfaces in all conditions. Tyre tread itself can become an issue, though, if the car's wheel alignment and suspension are not set correctly. 

In this case, the wear on the leading edge of the tyre tread pattern may be uneven compared to the back edge. This difference causes the front edge to wear much more quickly on the tread block, leading to a tread profile that looks a little like a saw blade, hence its name.

What causes saw-tooth wear?

Uneven tyre wear patterns can be caused by a number of different factors, usually related to the car’s suspension and wheel set-up, or combinations of them. When it comes to saw tooth wear, the main causes include:

  • A difference in the dampening set up of the suspension and the tyre system
  • Uneven distribution of pressures such as in the case of a front wheel drive car where the rear tyres may suffer from saw tooth issues
  • Incorrect tyre pressure for the weight of loads carried on board
  • Having directional tyres fitted the wrong way round
  • Parts of the car’s suspension being either worn out or not correctly set, e.g. ball bearings or sleeves
  • Having a load unequally distributed throughout the car so as to place uneven stresses on the tyres
  • Road conditions - even smooth driving on roads with relatively few curves may influence this type of tread wear
  • Elements of road surface, e.g. bumps, ruts and inconsistencies
  • Driving style, e.g. fast cornering

Saw tooth tyre wear versus road safety

Uneven tyre wear such as saw tooth tyre wear does not have significant direct impact on steering or handling the vehicle. It should not, therefore, be considered as a danger to road users. However, as tyre stepping means that certain deformation of the tread blocks in the contact patch of a tyre has occurred, it may cause some vibrations in the steering wheel. 

Additionally, saw tooth tyre wear can surely lead to much greater tyre loudness, particularly on less than smooth roads. The noises coming from unevenly worn tyres, usually described by motorists as droning or humming sounds, may be annoying and uncomfortable. 

A minor amount of saw tooth pattern wear is normal for many cars and it should not affect your driving in a noticeable way. But tyre stepping effects are irreversible so if you let the uneven wear grow deeper, then you may need to replace your tyres even if they are still relatively new and have a lot of thread left on them.

In case of a very strong saw tooth pattern wear that has not been checked for a long time, there is a risk of tyre damage such as patches on the surface of a tyre or even tyre blowout.

Preventing saw tooth tyre wear

If you want to protect your tyres against uneven tyre wear patterns and tyre stepping, remember that there can be problems with symmetrical and asymmetrical tyre types. Symmetrical or uniform patterned tyres, especially cheaper brands, are prone to this problem, as are asymmetrical or non-uniform tyres that are fitted so that they rotate in the wrong direction during normal driving.

Have your suspension checked for looseness or wear and get any misaligned or worn parts replaced. You should also check your tyre pressure and make sure you do not carry any unevenly balanced load. This is usually more apparent in two-wheel drive cars so if you have a 4x4, you probably suffer less from saw tooth wear.

Following these simple rules and carrying out regular checks on your car will enable you to react soon enough and prevent the effects of uneven tyre wear.