Picture of bald tyre

Would you feel safe?

Picture of depth gauge check

Tyre depth check

Pictures of cuts in side wall

Perished side wall

Picture of tyre size on side wall

Your tyre size

Picture of Passat Aquaplaning

Aquaplaning

Conti aquaplaning chart

Aquaplaning risk chart

Picture of wheel balance machine

Wheel balancing

Tyres - a guide to safety and buying


Know the Law

The law states that a tyre must have at least 1.6 mm of tread, for the entire circumference of the tread and for 75% of the width (measured from the centre) with no cords or buldges showing.

In the rest of Europe the law is 2mm and is still too low. A 2mm tyre is 94% worn. You wouldn't drive around on 94% worn brake pads would you? It also has twice the stopping distance of a new tyre.

A 3mm tyre is 78% worn and is a far safer prospect when you understand what can go wrong (See Aquaplaning below)

The penalty per tyre currently stands at up to £2500 and 3 points per offence.

It is estimated that 4 out of 10 vehicles on UK roads have 1 or more illegal tyres.

How to check your tyre condition

1. The visual inspection. Check the side walls for cuts, bulges and general cracks where the rubber becomes perished over time. Turn the steering on a full lock and check the inside edge as well. Many tyres have extra reinforcement on the side and it's not uncommon to see 'flaps' of rubber where you've caught the kerb or a pot hole. Lift back the flap with a pen or small flat-bladed screwdriver and check you can't see any metal cords sticking out. If you can, don't risk it - get the tyre changed.

Bulges are also bad news. This occurs where the cords are damaged internally and air pressure forces the rubber outwards. This is highly dangerous and can't be fixed - get a new one!

Some tyres will show light indents in the side walls, spanning from the top to the bottom. These are manufacturing moulding marks are are nothing to worry about.

2. The tread depth check. Now you know the law it's time to check you're legal. As you look at the road surface face of the tyre you'll notice small extra blocks of rubber recessed in the main tread. When the tread is level with these bars you've reached the 1.6mm limit (which is too low - see 'Aquaplaning' below and 'Know the Law' above)

Tyre makers provide marks on the side wall to show you where the 'wear bars' are. Generally the marks are evenly spaced around the side wall and are in the form of a small triangle or the letters TWI (Tyre Wear Indicator). Michelin provide you a mini Michelin man as their indicator. Sweet.

So, you've checked they're legal but high much tread is there left? Your best bet is to treat yourself to a depth gauge. They only cost a few pounds and are worth every penny. Buy a gauge here or hop down to Halfords or go on line to eBay.

What size are my tyres?

There are lots of numbers on the side wall of the tyre and can initially look complicated. The general format will be 205/55/R16 91V. Lets spend some time explaining them all -

205 - is the width of the tyre measured in mm

55 - is the height of the side wall measured as a percentage of the width. In this example it would be 55% of 205 = 113mm

R - is for radial - it's simply the way a modern tyre is constructed of overlaying bands of metal under the rubber surface.

16 - is the diameter of the wheel in inches! Yes, you read it right. We measure tyres in mm and wheels in inches. It's no wonder the rest of Europe won't let us have Jaffa's in the cake aisle.

91 - is the load rating. VW work out the safe carrying load of a vehicle and select a tyre that can operate safely within those limits.

V - is the speed rating. Each letter denotes the safe maximum speed that the tyre is designed to go. Sadly your car can't reach the speed of the tyre, nor will it go faster if you fit a higher rating! Just to add to the confusion the letters don't run in alphabetical order. An H is capable of fast speeds than an T for example. Never drop a speed rating to save money. Your insurance company would love to wiggle out of an accident claim if they spot that!

Finally, there's the name of the manufacturer, any information about the rotational direction of the tyre (very important if you swap the tyre sides), siding (inside or outside walls), the build date (normally in a box in the format build week/year) and an 'e' within a circle donating EU compliance and safety standards.

Which make should I go for? There's so many!

Tyre manufactures make many different claims about their tyres. We would always recommend going for the make that your Volkswagen came with. Suspension settings are tested with that tyre so changing them for another make is of course possible but may change the road noise, wear etc.

We also say stick to a household name such as Michelin, Dunlop, Goodyear, Bridgestone, Continental

Unknown makes and 'budgets' will get you what you've paid for. Expect excessive road noise and odd wear patterns. Worse still poor build quality and rubber may compromise braking and handling. Best to 'stick' with the good stuff.

Aquaplaning - why you need plenty of tread

On your list of things to do before you're forty, Aquaplaning shouldn't be one of them. It's a heart stopping experience and one you won't forget in a hurry. Let's explain why it happens -

As you drive along water is forced into the grooves between the blocks in the tread and out and away from the tyre. At this stage the tyre still has maximum traction for the conditions. The lower your tyres are, the less space for water to pass through. If water can't escape faster than it's forced in, the tyre is pushed up and away from the road.

In extreme cases the tyre is actually lifted clear of the road. This can happen under braking (as a wedge of water forms at the front of the tyre), during cornering, or hitting patches of laying surface water.

When it occurs you can steer and brake as much as you like - nothing will happen. It's like driving on ice. The car will continue in the direction you were last heading or spin out completely.

Avoid it all by changing your tyres at no less than 3mm and keep those pressures where they should be!

Tricks of the Trade when buying a tyre

You need to be careful when getting quotes. A common sales pitch is to give you a 'can't refuse' price. When you come to pay they'll ask you if you would like the wheels balanced at an extra cost and would you like a new valve? You need both done and we'll explain why below.
The simple rule is this. Make sure the price you get is for EVERYTHING. That's fitting, balance, valve, disposal of your old tyre and VAT. Follow that and you'll be comparing eggs with eggs.

Buying Part Worn tyres

Have they been kerbed? Have an unseen defect? Who knows. Unless you're really strapped for cash they're best avoided. Not to put too fine a point on it but your life literally depends on your tyres. It's just not worth taking the chance.

Puncture repairs

There's nothing wrong with a quality puncture repair. Having said that, the UK's emergency services won't have them done in case of failure. Don't be surprised however if your garage tells you it can't be repaired. Modern tyres have 'ribs' on the inside for strength and you can't patch on top of them. The centre smooth section of the inside of the tyre is the only repairable surface and this is normally only 5 or 6 inches wide.

It's a good idea to get a new valve when your tyre is refitted. They cost less the £2 and are well worth it. If the machine has caught the inside of the valve or there's some other defect it could lead to sudden deflation.

Wheel Balance

Wheels and especially tyres aren't perfect. Even from new there are uneven areas, let alone after a few miles of pot holes, wheel spins and the inevitable odd contact with the kerb. Wheel balancing deals with these imperfections by adding weights to the wheel to compensate. You will see them as silver blocks of metal stuck inside the rim on alloys or hammered onto the rim of steel wheels.

'Out of balance' wheels will cause patchy tread wear and add to the stress forces on steering and suspension components. The symptoms of incorrect front wheel balance will be 'shimmying' (shaking) through the steering wheel, normally at motorway speeds. Rear wheel balance issues will present themselves as a vibration felt through the base of your seat. Balancing each wheel will cost between £10 and £20 on average but should be part of the 'package' deal when fitting a new tyre (See Tricks of the Trade above).

For advice on tyre pressures see our guide.

Whilst vwgenuineparts.co.uk has researched the facts to the best of its ability, the opinions expressed in this article represent those of individual writers and unless clearly stated as such do not represent the opinions or policies of vwgenuineparts.co.uk. No claims are made or responsibilities assumed for the contents of externally linked websites. Unless otherwise stated, all contents are copyright ©

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