Classic car tyres

When it comes to maintaining your classic car, we bet you've got a decent checklist of all the essentials you need to look after: engine, brakes, transmission, interior and so on. But how often do you consider your car's tyres?

Car tyres are often overlooked when it comes to classic car maintenance. After all, they won't seem as integral a part of your vehicle – as quintessentially a piece of, say, Jaguar, BMW or Citroen machinery – as its engine or suspension. But you'd be wrong not to take your car tyres seriously. You may spend thousands of pounds on your engine, upholstery and brakes: but if your tyres aren't fit for purpose, all that could be for nothing. Driving with worn or incorrect tyres could be a major safety risk – and could also invalidate any claims on your classic car insurance policy, in the event of damage to the vehicle.

Tyres are a hugely important part of your car to get right. Read on for our guide to choosing the right rubber – and the right time to get back to the tyre shop for a replacement. In this guide, we'll discuss the various types of tyres (radial, cross-ply, and others), and look at which will be a best fit for your classic.

The importance of good tyres

Tyres have a crucial role to play in your car's safety. They are – when all is well – the only part of your vehicle that makes contact with the road and it's crucial that that contact is a safe one, with plenty of grip. Indeed, the state of your tyres will have a bigger influence on your car's handling, braking and general on-road stability than any modification you might choose to make to the vehicle.

We shouldn't be surprised, then, that tyres are – after blown bulbs – the second biggest cause of MOT failure. Faulty tyres will also, very probably, invalidate your classic car insurance

In the unfortunate event of your vehicle getting into a scrape. So yes, the right tyres in the right condition are, frankly, crucial to the safety of your car. Read on as we discuss how to ensure that they’re doing their important job properly.

So whether you’ve got a front-wheel or rear-wheel drive classic, read on to find out what types of boots they should be wearing.

Different types of tyres

Throughout motoring history, there have been various types of tyres – although you will find that, according to the age of your vehicle, one or perhaps two types will suit it best.

'Beaded edge' tyres

This type of tyre has a large ridge of hard rubber all around its circumference. The 'beads' (or ridges) on this type of tyre are designed to slot into the hook of the wheel's rim. This means that beaded edge tyres need to be maintained at an inflation of 60PSI or more, to enable them to be pushed into the hook.

Beaded edge tyres are mostly often found on veteran European cars: if your own classic dates from any time during the last half century, you are unlikely to require this type of tyre.

Wired-on tyres

This type of tyre was essentially the successor to the beaded-edge type that we described above. Safety was greatly increased, thanks to the presence of a solid wire within the body of the tyre, providing rigidity and making sure that the tyre bead wouldn't stretch and lose its structural integrity.

Cross-ply tyres

The next stage in the tyre story was the arrival of 'cross-ply' tyres. This new generation of tyre took its name from its composition: the layers of textile inside the tyre ran at alternate angles from one bead (edge) to the other. This allowed both the tyre sidewall and tread to be part of one overall structure.

Radial tyres

The most recent major development in tyre technology came back in 1948, when Michelin patented the radial tyre. In this type of tyre design, the ply cords radiate from the wheel rim at right angles, while the tyre casing is reinforced using a belt of steel fabric running right around the circumference. If all of this sounds somewhat technical, the take-home is this: radial tyres give a car increased flexibility, while at the same time ensuring that the maximum possible surface area maintains contact with the road surface. Result? Better, safer handling.

In fact, although they started to be introduced from the early 1950s onwards, radial tyres didn't really enter the motoring mainstream until the 1960s. The reason for this is that, for the first few years, radials were simply noisier. On top of that, the majority of cars on the road didn't really offer the kind of speed and performance that warranted the new tyre type with its superior handling.

Radial v cross-ply in more detail

If you drive a classic car built over the last 60 years or so, you probably have a choice between using radial and cross-ply tyres. For this reason, it's a good idea to be familiar with the two designs, and their respective pros and cons.

As a reminder, in cross-ply tyres, the fabric 'cords' are arranged at a 45-degree angle to the centre line of the wheel and crisscrossed. The radial design, conversely, features strips of overlapping fabric laid at a 90-degree angle to the wheel's centre line.

This means, among other things, that cross-ply tyres have stronger, more rigid (and therefore less flexible) sidewalls. This can be an advantage, as it protects the inner tube that is so essential in cross-ply construction. Radial tyres, on the other hand, do not require an inner tube – instead, the entirety of the tyre performs the latter's function. In this case, the advantage is that a more flexible sidewall is better able to absorb vibrations from the road and is far less likely to overheat.

Ways in which radial tyres outperform cross-ply tyres

As you might expect, as a more modern development, radial tyres perform better than their cross-ply rivals in a number of ways. And these advantages made radials the default choice on most cars by the 1970s.

For example, radial tyres typically offer better fuel efficiency than cross-ply or other tyre types. Of course, to maximise fuel efficiency you need to ensure that your tyres are properly inflated – something we'll come onto later in this article.

Radial tyres also deliver superior handling and ride comfort. This is essentially because that more flexible tyre sidewall means that their shock absorption is far better, giving you a more cushioned ride with fewer bumps finding their way through to you in the cabin.

How do the two tyre types compare in terms of safety, though? Well, it's safe to say that the firmer makeup of cross-ply tyres means that they lose heat less quickly, and as a result are likely to degrade faster. That means that the tyres' grip and traction will decrease more quickly, and accidents will be more likely. If you do have an accident or suffer damage to your car and your tyres can be proven to have been unfit for purpose, you may well find yourself unable to claim on your classic car insurance.

Cross-ply tyres also feature a lower speed rating – a maximum speed at which they can be safely driven. This is another topic that we'll cover in a little more depth further down: for now, suffice to say that, when driven at high speeds, cross-plys are more susceptible to blowouts than radial tyres.

So much for their advantages, then. But do radials have any downsides in comparison with cross-ply tyres? Well, being more flexible, that sidewall is more vulnerable to damage if it is underinflated, or if the car is overloaded. We'll come onto the risks of overloading your vehicle a little further down: suffice to say that this practice can be very unsafe, as well as potentially invalidating your classic car insurance.

Finally, radials are also typically more expensive than cross-ply tyres – although the costs are largely offset by their longer working life.

Don't mix tyre types

One thing you definitely shouldn't do, when it comes to tyre safety, is mix tyre tapes. For one thing, it's illegal to mix any two types – cross-ply and radial-ply, for example – on the same axle, whether front or rear. It is also illegal to mix tread patterns, tread depths and tyre sizes on the same axle, too.

Drive with two different tyre types on the same axle and you will be contravening the law. The thinking behind this rule is clear: different types handle quite differently, and have a different rolling radius. This can play havoc with how the car behaves on the road. By the way, this would be particularly harmful in the case of any vehicle fitted with a limited-slip differential – a specialist bit of kit mostly for more performance-oriented cars, which we discussed in more detail in this article.

Tyre codes explained

If you've ever taken more than a passing glance at your tyres, you may well have gazed quizzically at those strange sequences of numbers and letters inscribed on the sidewalls. What do they all mean? Let's go through the sequence in order.

On a typical tyre code, such as, say, 185/65 R15 88 H, the various parts of the code mean the following:

• 185: this (measured in millimetres) is the cross section width, or the width of the tyre, from the inner sidewall to the outer.
• 65: this is the aspect ratio, also known as the profile. In other words, this is the height of the sidewall, as a percentage of the cross section width above. In this example, then, the sidewall will measure 65% of 185 millimetres – so, 120.23 millimetres.
  And how does aspect ratio, or profile, impact on how a car drives? Well, as well as adding a sportier look to a car, low-profile tyres can boost a car's handling. Those shorter sidewalls are less flexible than taller sidewalls on high-profile tyres. Result: the car won't roll and bounce about quite as much. So, depending on what handling characteristics you are looking for, you may want to look for a low or high profile. Lower-profile tyres deliver sharper, firmer handling – but the trade-off will be a slight decrease in ride comfort.
• R is the label for the particular tyre type or tyre construction – in this case 'R' for radial, which is by far the most common you'll see.
• The 15 refers to the rim size – the diameter of the rim, measured (unlike the tyre width above) in inches. In this case, we are looking at a 15-inch rim. Most car wheels are somewhere between 13 and 19 inches.
• Next, the 88 is the load index. That's the maximum amount, in kilograms, that the tyre can carry. Note that the number on the tyre itself isn’t the maximum weight – instead, it corresponds to a weight on a standardised chart of tyre loads. You can find a tyre load rating table on many different sites online – here is one on the Government website, for example. You can see from the table that, for example, a tyre bearing the load rating '62' shouldn't carry more than 265kg, whereas a tyre rated '95' can carry up to 690kg. Two things to bear in mind here: that weight relates to the car as a whole, so it's not a case of multiplying that figure by 4 (once for each tyre). Rather, that 265kg (or 690kg, etcetera) is the maximum weight you should carry (including yourself and passengers) in order not to endanger the tyres.
  Secondly, you should also be aware of your vehicle's own maximum carrying weight, which will often be lower than what your tyres can carry. Many smaller cars may have a maximum payload of around 500kg, for example. Again, get to know this weight. In the event of an accident or damage to your car, evidence that you went over the payload may invalidate your classic car insurance claim.
• The last section of code refers to the speed rating. In the example we've given above, the speed rating is H, meaning that that particular tyre is safe up to a top speed of 130mph. It goes without saying that you should never exceed the top speed specified by your tyre – although this will often, in any case, be higher than the legal speed limit of the road(s) you are travelling on. An example of the chart for converting these alphabetical speed ratings into maximum permitted speeds can be found on that same Government webpage that we mentioned above.

Checking on the health of your tyres

So, we've looked at which tyre(s) will best suit your car, and also had a go at deciphering the various bits of crucial information displayed on tyre sidewalls. Next, we've got some general advice on looking after your tyres. It's important to monitor their general state of health, and knowing when they need to be replaced.

For this reason, we recommend making regular checks on the health of your tyres. Two particular tyre health aspects to check in on regularly are tyre pressure and tread depth.

You can consult your car's handbook to find out the recommended tyre pressures for the vehicle. Always inflate your tyres to the specified pressure: this will save you money on fuel (a car with underinflated tyres will need more fuel to keep the tyres moving) and will also be safer, both for you and for any passengers you're carrying.

Tread depth refers to the depth of the grooves on the tyre's road surface. It is essential that these little grooves are sufficiently deep to provide proper traction. The minimum tread depth for driving on British roads is 1.6 millimetres.

One easy way to check this is by using a 20p coin. Slide the coin into those tyre tread grooves. If the coin's outer band is now hidden within these grooves, you're fine: the treads are at that 1.6mm minimum or higher. However, if you can still see some of the outer band of your 20p coin, your treads have worn themselves out to unsafe levels, and you need a new tyre. Note that this 1.6mm tread depth must be maintained on a continuous stretch around 75 per cent of the centre of the tyre – so carry out the test at various intervals around the tyre circumference.

Lastly, we recommend making regular checks on your tyres' general condition, over and above tread depth and pressure. Check the tyre sidewalls for any small cuts or damage that could result in a puncture. Also monitor the general condition of the rubber all around the tyre. If it's looking cracked and dry, it may well be time for a replacement. If the tyre is showing a lot of wear in the centre, that's a sure sign that it has been over-inflated: excessive wear on the edges, conversely, indicates an under-inflated tyre.

Performing this kind of health check is not just useful in itself: it can also alert you to other problems with your car's inner workings. If, for example, you can see some irregular wear to the tyre – to one side more than to the other, for example – you may have some issues with your steering or suspension. We'd recommend getting the car looked at by a specialist garage.

How long can tyres last?

Quite apart from looking for any visible signs of wear and tear, you should also keep a note of the age of each tyre, as well as how long it's been fitted to your car. Tyres will not last forever: essential elements begin to filter out of them right from the beginning, due to the effects of heat, rain and ultraviolet light. This process will happen even if the tyre gets minimal use, or no use at all. This process of wear and tear may not be serious for the first few years, but generally after four to five years tyres will inevitably start to do their job less effectively.

Most tyre manufacturers and car safety groups agree that tyres should typically be replaced, irrespective of their condition, every five to six years. You can check the month and year of your car tyres' production by – you guessed it – looking at the information on the tyre sidewalls.

Somewhere on that sidewall you will see a sequence of four single digits. These indicate the tyre's year of manufacture, with the first two denoting the calendar month and the second pair representing the year. So, for example, a tyre bearing the four-number sequence '0615' was made in June 2015, while one labelled '1120' dates from November 2020.

Classic car insurance: another key part of the safe driving jigsaw

As you can see from this article, having the right tyres for your vehicle, in roadworthy condition, is a crucial part of driving safely. Another part of that particular equation is, of course, some specialist classic car insurance. Why not contact us for a classic car insurance quote today?

Policy benefits, features and discounts offered may very between insurance schemes or cover selected and are subject to underwriting criteria. Information contained within this article is accurate at the time of publishing but may be subject to change.