The only contact your vehicle has with the road is through its tyres. The total tyre contact area for an ordinary car is often little more than the size of an A4 sheet of paper. It is therefore essential you have the correct tyres fitted and they are inflated to the correct pressure. They must also be roadworthy and regularly inspected for damage and wear as it is through the tyres that you are able to accelerate, brake, corner and steer safely.
The type and size of tyres fitted will have been carefully specified by the vehicle manufacturer to take account of the vehicle and its loadings. The tyres should be able to grip the road surface in most weather conditions and dissipate the heat produced as they flex when moving at speed. Needless to say, heavy demands are placed on them and they are a key safety component of your vehicle.
Modern tyres typically feature a radial type structure, although the much less common cross-ply version still exists. Both terms refer to the tyre's internal structure and the two types of tyre are quite different and they behave differently under load. It is an offence to mix radial and cross-ply on the same axle.
Cross-ply tyres are no longer widely available so when a replacement is required radials may have to be fitted. However, you can only use tubeless radial-ply tyres if the wheel is one of the safety rim type, which have a hump or flat ledge on the outer bead seat.
Older caravans, over 25 years old, may not have safety rims. In these cases it may be possible to fit radial tyres with an inner tube. Not all radial-ply tyres are suitable so consult a tyre specialist.
Most tyres supplied in the UK are a summer tyre, which are optimis
ed for use in warm months and will perform well enough in most conditions. For those wishing to travel further afield or live in cooler parts of the UK there are also all-season and winter tyres to choose from.
An all-season tyre tries to achieve everything - offering reasonable performance in cold, snowy, warm or wet conditions - a tall order for any tyre. They have a place in the market but applications can be quite limited.