What is a Tyre
They’re round, black, made of rubber and have a hole in the middle. Tyres. Not the most exciting part of a car, but they are a vital component of your vehicle however, and have a big influence on its performance.
What does a Tyre do
The tyres have to transmit all of the cars driving, steering and braking force to the road surface.Your only contact with the road are the four postcard size ‘footprints’ of your tyres which have to perform safely on all types of surfaces and in varying weather conditions. That little bit of rubber has an awful lot to do, therefore it is imperative that you keep your tyres correctly inflated and free from any defects.
Tyre Anatomy
The diagram below shows a typical section through a tyre and lists some of its anatomy.
Tyre Types
Tyre technology has progressed and when the Ford Anglia and Ford Prefect came out, they were running around on Cross Ply Tyres. Now, it is more common for cars to have Radial Tyres fitted as standard. This improves the handling no end, and are relatively easier to obtain, but what is the difference between Cross Ply and Radial Tyres.
Cross Ply Tyre
The casing of a cross ply tyre consists of a number of rubberised cord plies with edges wrapped around the bead wires (the bead ensures that the tyre sits firmly on the rim). The number of plies determines the load capacity of the tyre. Cross ply tyres for passenger cars generally have between two and six rayon or nylon cord plies.
Cross ply tyres are few and far between on modern cars nowadays, having pretty much been replaced by radial construction in the UK, but if you so desired, you can still buy cross ply tyres for your Anglia / Prefect from specialist dealers.
The diagram opposite shows a typical cross ply tyre construction. The angle of the plies determines the stiffness of the tyre. The sharper the angle the stiffer the casing.
Radial Tyre
In more modern times, the radial – or belted – tyre has completely replaced the cross ply tyre here in the UK. The cords in a radial tyre casing run perpendicular to the direction of travel. Viewed from the side, the cords run radially – giving the tyre its name.
The weakness of this arrangement is that the cords cannot sufficiently absorb lateral forces when cornering or circumferential forces when accelerating. To compensate for this, the cords must be supported or complemented by some other structural elements (ie steel belts)
The diagram opposite shows a typical radial carcass construction. You can see that the cords of the carcass run at 90 degrees to the perpendicular.
Checking your Tyres
A tyre should wear evenly and last for quite a few thousand miles. Often though, tyres have to be replaced long before their specified life has been reached principally because of rapid or uneven tread wear, usually due to a lack of vigilance on the Owners part. Regular checks on the tyres could eliminate most of the tyre were problems.
The most common causes of avoidable tread wear are:
Under Inflation
Under-inflation has caused this tyre to wear on the outer edges of the tread, leaving the central tread area far less worn. The tyre inner-liner can also degrade.
Over Inflation
Over-inflation has resulted in the central tread area being forced into contact with the road causing rapid or crown wear.
Mis-Alignment
A typical example of the wear pattern caused by front wheel misalignment, (Toe-in or toe-out). The edge of the tread is “feathered” and worn progressively from one side.
Camber Wear
Excessive wheel camber has caused sloping wear on the outer edge of the tread on one shoulder of this tyre.
End Of Life
This tyre has reached the legal minimum pattern depth of 1.6mm.
Illegal Wear
This tyre has been used well after reaching the legal minimum pattern depth. (see depth of tread in UK Law below)
Cuts
Sharp objects can cause considerable damage rendering a tyre unserviceable.
Impact Damage
This is damage caused by an impact to the sidewall. The bulge or “egg” indicates localised casing damage.
Second hand tyres
Replacing worn or damaged tyres with second hand tyres (rather than new) can be risky. Unless you
know the tyres history and can be sure they haven’t been damaged or abused, do not even consider buying them.
Recommended Radial Tyres
After all of this blurb, the one question you want the answer to is:
“Which Radial Tyres shall I use on my Anglia / Prefect”
The equivalent Radial Tyre for the Anglia / Prefect is a 155/80 x 13” (filled to 26 psi)
There are also specialist dealers that will supply 155 x 13” Radial tyres with full white walls or ones with a white band, so that you can still get that 1960’s look and feel for the vehicle.
Tools Required
The Anglia and Prefect can use either Cross Ply or Radial Tyres.
To remove, check and clean the tyres, you may need some of the tools shown below.
The minimum being some sort of car jack and wheel brace to remove the lift the car and remove the
wheels.
The UK Law about Tyres
Like most things in the UK there are lots of laws relating to the tyres on your vehicle. The penalties for having illegal tyres are currently up to a £2500 fine and 3 penalty points PER TYRE! so take care to look after your tyres.
Here are just a few of the UK Laws to remember (there are lots more!)
The legal limit for minimum depth of the tread on your tyres is 1.6 millimetres, across the central 3/4 of the tread around the complete circumference of the tyre.
Your vehicle is required to be fitted with the correct type and size of tyre for the vehicle type you are driving and for the purpose it is being used. Mixing brands and patterns of the same construction type
is permissible. It is also a legal requirement to ensure that tyres of different construction types are not fitted to opposite sides of the same axle. (ie The two main tyre types are radial and cross-ply, and these must not be mixed on the same axle). Also you must NOT have radial tyres on the front wheels and cross ply tyres on the rear wheels.
All tyres must have a service description (i.e. load and speed index)
If the vehicle was to operate outside the service description indicated on the sidewall e.g. at a higher speed or overloaded, then the tyres would be deemed to be unsuitable for the use, and a prosecution could follow.
A tyre cut in excess of 25mm or 10% of the section width of the tyre, whichever is the greater, measured in any direction on the outside of the tyre and deep enough to reach the ply or cord would deem the tyre illegal.
All tyres marked “Temporary Use Only” are restricted to 50mph.
Re-grooved tyres are illegal on any passenger car or utility vehicle below 3500 kgs GVW.