How do you know that your tyres need replacing? In our last blog post, we pointed out four early warning signs that your tyres are past their best. However, the more obvious way is to take a look at them. In this post, we will do just that.
1. The tread is worn
Let’s start with the biggest and most obvious one. Legally, the minimum depth of tread you need to have is 1.6mm across the central 75% of the tyre. However, tyres with less than 3mm of tread show markedly increased stopping distances. This is most apparent in wet conditions, because worn tyres cannot clear the film of water underneath them so effectively. A vehicle running on 1.6mm of tread may require 44% extra stopping distance in wet conditions, compared to a vehicle with 3mm tread depth. That’s a massive, and potentially life-saving distance. For this reason, we always recommend that tyres are changes well before they reach the legal minimum.
Although using a tyre gauge is obviously more accurate, the easy way to check you have adequate tyre depth is with the well-known 20p coin test.
The 20p test – with thanks to TyreSafe.
A quick and easy way to see if your tyre tread exceed the minimum legal tread depth is to take the 20p test. Just press a 20p coin firmly into the grooves in the tread. The rim or band around the coin should not show clear of the groove. If it does, you could well be below the legal limit.
Don’t just check one groove in one place – check in at least three different locations to get a true picture.
2. Cracking and crazing in the sidewall
As tyres deteriorate, they become less elastic, more brittle and more liable to fail. There are many reasons for this, including exposure to UV light, cleaning products or simply ageing.
One sign of this deterioration is the appearance of cracks or crazing in the tyre’s sidewall. If this becomes significant, it’s time to get the tyre replaced. An experienced professional fitter will be able to assess this at a glance.
3. Cuts and bulges in the sidewall
Photo courtesy of Pistonheads
When your car is moving, the pressure on the sidewall of the tyre increases. Although tyre sidewalls are tremendously strong, any damage to them may cause significant weakening. That’s bad news, because damaged sidewalls are liable to fail without warning, causing a blow-out.
Bulges, bubbles, cuts and tears in the sidewalls are all signs that the tyre needs further inspection by a professional – and the likely diagnosis will be that a replacement is necessary.
Damage can occur through hitting the kerb, stray nails and other sharp metal objects, hitting a particularly bad pothole and so on.
And speaking of stray metal objects…
4. Punctures in the tyre
Even the less observant are likely to spot when their tyre has lost pressure. Often, the cause may be a puncture caused by a sharp object such as a nail. This might mean your tyre needs replacing – or it might not.
Punctured tyres are potentially repairable if (a) the puncture damage is less than 6mm in diameter and (b) the puncture is in the central tread section of the tyre. However, if the shoulder or sidewall have been damaged, the tyre will have to be replaced.
If the tyre has been running on low pressure for some time, the internal structure may be damaged. Low pressures generate heat, which can damage the tyre. Again, the risk is of catastrophic failure.
For the full story on this, we recommend that you read There’s a nail in my tyre – can you repair it?
Inspecting your tyres – a good habit
Many motorists rely on their garage to tell them when their tyres need replacing. This may mean that long periods of time pass without the tyre getting any sort of check. And as your tyres are the only thing holding you on the road, that’s not a sensible policy.
Giving your tyres a visual once-over every fortnight or so, and before any long journey, is a good habit to get into. It only takes a minute or two and it could mean the difference between a safe journey and an unsafe one.
If you’re unsure about something you’ve spotted, give our friendly experts at BK Tyres a call. We can ascertain quickly whether your tyre needs replacing, and if it does, we can carry out the work at a location convenient to you. You can also buy tyres from us at great competitive prices.