How can you tell if a tyre is too hard or too soft?

How can you tell if a tyre is too hard?

A tyre that is too hard results in a loss of grip and increased noise; this is often caused by the rubber ageing, low temperatures or excessive pressure.
This manifests itself in poorer grip on wet surfaces, a longer braking distance and frequent ‘squealing’ when pulling away and on bends. On visual inspection, micro-cracks can be seen on the tread and the sidewalls. The rubber feels ‘glassy’ to the touch; it is difficult to leave a mark with a fingernail. The car can feel a bit twitchy over bumps, and the centre of the tread wears out more quickly at high tyre pressure.

What are the signs that a tyre is too soft?

Symptoms of tyres that are too soft include the car ‘wobbling’, delayed steering response and increased fuel consumption, usually caused by tyre pressure being too low or insufficient sidewall stiffness.
You can feel the tyre wobble on bends, and the front end dives more than usual when braking. The tyre flexes excessively, and creases are visible on the sides. The tread heats up quickly, and there is a smell of burnt rubber. Tread wear is increasing on the outer edges, and at higher speeds the car can become unstable in ruts.

How can you check a tyre’s pressure without specialist equipment?

It is possible to assess tyre hardness yourself without a durometer using a few simple methods:

• Close inspection: look for micro-cracks, radial cracks, discolouration and rubber that looks ‘glassy’.
• The nail test: fresh rubber under the nail will bend noticeably. If it is very hard, the nail will leave almost no mark.
• Deflection under load: at the correct pressure, the tyre ‘sags’ slightly. If it is very hard, it looks as though it is fully inflated; if it is very soft, the contact patch is visibly flattened.
• Test drive: excessive noise, squealing at low speeds and a rapid loss of grip suggest a hard compound or over-inflation. ‘Floating’ and sluggish responses indicate that the tyres are too soft.
• DOT date: tyres harden over the years; check the last four digits of the DOT code on the sidewall of the tyre, where the first two digits indicate the week of manufacture and the last two the year, allowing you to estimate the tyre’s age.

If in doubt, a wheel-balancing and road test service will help. Such a test detects uneven tyre stiffness and allows you to assess the tyre’s condition under load.

How does tyre pressure affect tyre hardness?

Tyre pressure determines the degree of sidewall flex and the size of the contact patch with the road, and its level directly affects the perceived firmness of the tyres.
Tyre pressure determines the degree of sidewall flex and the size of the contact patch with the road. If the pressure is too high, the tyre behaves like a ‘hard ball’. Comfort is reduced, the centre of the tread wears out faster, and grip on uneven surfaces decreases. Too low a pressure results in a soft ride, increases the tyre temperature and raises the risk of damage. Remember that tyre pressure changes with ambient temperature. Check the pressure when the tyres are ‘cold’, ideally before driving. Cars fitted with TPMS may alert you to any deviations. At a service centre, you can also have your tyres filled with an inert gas, which stabilises pressure fluctuations.

How does tyre tread wear differ between hard and soft tyres?

Tread wear on tyres of different hardnesses follows specific patterns:

• Too hard or over-inflated: faster wear of the centre of the tread, possible ‘stepping’ on the tread blocks and increased noise.
• Too soft or under-inflated: accelerated wear on the outer edges, frayed sipe edges, signs of overheating.
• An ageing compound: micro-cracks, a dull appearance, and poorer grip on wet surfaces despite the tread appearing to be in good condition.

Uneven tyre wear can also be caused by poor wheel alignment or imbalance. Having the wheels balanced – including a road test – and having the suspension alignment checked can help.

What impact do hard or soft tyres have on safety?

Both tyres that are too hard and those that are too soft have a negative impact on safety, increasing braking distances and the risk of losing control of the vehicle, as a tyre that is too hard does not ‘grip’ the road surface as well, particularly in wet and cold conditions.
If a tyre is too soft, it heats up, which can lead to internal damage and failure at higher speeds. Underinflated tyres increase the risk of overheating and damage, whilst worn tread and excessive speed are the main factors increasing the risk of aquaplaning. Over-inflated tyres transmit vibrations to the suspension and provide poorer braking on bumpy roads.

When should you adjust the tyre pressure, and when should you replace a tyre?

Tyre pressure should be adjusted whenever it deviates from the values recommended by the vehicle manufacturer, particularly following changes in temperature or load, or before a long journey. Decisions on when to replace a tyre are made on the basis of the following criteria:

• Tread depth below the limit. In Poland, the minimum is 1.6 mm.
• Cracks, bulges, cuts or exposed reinforcement.
• Frequent pressure drops despite the absence of visible nails.
• Significant tyre ageing, even when the tread appears to be in good condition.
• Uneven wear that cannot be corrected by wheel alignment or wheel rotation.

The tyre service will check your tyres, wheels and TPMS, balance your wheels and, if necessary, repair or replace a tyre. A mobile service and wheel straightening are also available.

How do you choose the right tyre hardness for your riding style and conditions?

Choosing the right tyre hardness depends on your driving style and conditions, to ensure safety, comfort and durability:

• City driving and comfort: tyres with more flexible sidewalls, a higher profile, and a focus on comfort and shock absorption.
• Roads and motorways: a more stable sidewall, a higher load and speed index, and more precise handling under load.
• Dynamic driving: stiffer sidewalls, reinforced construction, regular tyre pressure checks to ensure stability.
• Changeable weather: choose a season-specific tyre to suit the conditions, and treat all-season tyres as a compromise. Remember that temperature has a significant impact on perceived hardness.
• Cargoes and fleets: pay attention to the load-carrying capacity index and any reinforcements.

It is best to consult a service centre when choosing tyres, as they are familiar with the actual design differences and will match the tyres to your vehicle and mileage. You can also have TPMS diagnostics, wheel balancing with a road test, tyre and wheel repairs, and wheel straightening carried out all in one place.