Under Regulation 212 of the National Road Traffic Act, tyres must have at least 1 millimetre tread, and if it falls below that figure, motorists may be fined. Unfortunately, as is the case in most areas of the country, enforcement is sorely lacking. African News Agency (ANA)

They’re the only part of your car in contact with the road and the only things protecting you from its surface. And while we might not give our car tyres much thought - or when we do, we run them for just a little longer than they’re intended - but tyres are safety-critical features.

Tyres are components that shouldn’t be scrimped on: You might get away with saving costs on spare parts for your vehicle, but buying cheap, used tyres can be hazardous and costly in the end.

Under Regulation 212 of the National Road Traffic Act, tyres must have at least 1 millimetre tread, and if it falls below that figure, motorists may be fined. Unfortunately, as is the case in most areas of the country, enforcement is sorely lacking.

What qualifies as part-worn?

If you’ve ever bought a second-hand car and not replaced the tyres at the same time, those are, in effect, part-worn. You don’t know what they’ve been put through - the curbs or potholes they’ve hit, the punctures that have been plugged, or the conditions they’ve been exposed to.

Then there are part-worn tyres that are sold second-hand: they might still have plenty of tread left, a few hundred kilometres run left in them, and cheaper than new. You might even prefer to be able to afford a better quality tyre from a big-name brand, rather than a budget tyre from a manufacturer in the East that you’ve never heard of.

Why it’s a bad idea

Part-worn tyres might look fine on the outside, but on the inside - where it really matters - there might be a host of hidden dangers that reduce vehicle handling, braking and could cause blow-outs.

Using inferior tyres can also invalidate your insurance because insurers stipulate that insured vehicles must be roadworthy. And you don’t know the history of a part-worn tyre.

Riaz Haffejee, the chief executive of Sumitomo Rubber South Africa (manufacturer of Dunlop, Sumitomo and Falken tyre brands), says unsafe and unregulated part-worn and second-hand tyres threaten to undermine manufacturer efforts to uphold consumer and tyre safety and accessibility. And because there’s a lack of prescriptive regulation in the second-hand industry, road users are exposed to greater cost and hazard.

“As a regulatory-compliant tyre manufacturer, we are well aware that we are responsible for the lives of many daily, because the products we put out into the market are the only part of a vehicle that touches the road surface and could mean the difference between a safe journey and an unsafe one, or life and death. “It’s therefore a non-negotiable that tyres are a priority focus for road safety, the unregulated second-hand tyre industry on the safety of road users.”

Dunlop has just been voted the number one tyre brand in the 2019/2020 Ask Africa Icon Brands Survey, for the seventh time since 2011.

Danger zone

A part-worn tyre also shows reduced performance over new tyres, especially in wet braking, and up to a 33% reduction in handling ability according to the Automobile Association.

Last year, the AA conducted a safety demonstration at the Gerotek test facility west of Pretoria, highlighting the dangers of driving with worn or damaged tyres.

In South Africa, the legal limit for tyre tread is 1mm across 75% of the tyre - in Europe, it’s 1.6mm.

The tyres used in the demo were all skimmed to around 1.6mm.

In one demonstration two identical cars drove on a wet skidpan to test braking; the car with the new tyres stopped considerably quicker, and better, than the car with the worn tyres.

In another demo, two cars were driven at high speed on a wet track, causing them to aquaplane. The vehicles with worn tyres struggled to maintain any traction with the road and displaced noticeably little water.

It advises that motorists check their tyres regularly, and replace them if needed: Not only for their own safety but also for that of other road users.

How to tell

The Automobile Association notes that some tyres have wear indicators in the tread pattern to show when the tread depth is less than 1.6mm, which is the legal limit in Europe. Once the tread is level with the indicator, the tyre must be replaced because it is considered unroadworthy.

To check the tread, it advises: “A simple way to test this is to insert a match horizontally between the treads on the tyre. If the match is level, the tread may still be good. However, if the match protrudes from the tread, it is time for a replacement.”

Under-inflation is another critical factor: Under-inflated tyres have more rolling resistance, so they will also increase fuel consumption. And over-inflation, the AA says, reduces the cushioning power of the tyre. “Over-inflation also means there is less contact with the road surface which has a negative impact on road handling.”

AA spokesperson Layton Beard says people don’t realise how critical tyres are to safety. “Replacing tyres and servicing can be expensive, which is why we would recommend buying an extended maintenance plan, or setting aside money for those services and tyre replacements so it’s not such a shock.”

* Georgina Crouth is a consumer watchdog with serious bite. Write to her at [email protected], tweet her @georginacrouth and follow her on Facebook.