The writing on the sidewall of your tyres provides all the information needed to establish the specification of the tyre.

When you ring for the best price and availability on any of the tyres at Christchurch Tyre Co, you can give us this information to help us deal with your enquiry quickly.

We can normally look up the make and model of your vehicle, but in many cases factory option or aftermarket wheels have been fitted which may differ in size so it’s always best to make a note of the information on your existing tyres.

It is very important that you purchase the correct specification for your vehicle type, wheel size and intended use.

Hear is a quick summary of the four main pieces of information required:

Tyre Width
This is the width of the tyre section in millimetres and should always be appropriate for the width of the wheel rim. Although you can increase the tyre width by one size we do not recommend this.

Profile
Also known as the aspect ratio, this number represents the height of the sidewall as a percentage of its section width. The smaller the number, the lower the height of the sidewall. The lowest profiles are normally associated with high performance cars, whereas medium profiles are used on family cars to give a more comfortable ride.

Wheel Diameter
This is the inside diameter of the tyre and this corresponds directly to the wheel diameter. The diameter is represented  inches, not millimetres.

Speed Rating or Performance Index
Although its not illegal to have a tyre with a lower speed rating than the vehicle requires, it is always recommended that the correct speed rating is used. This is particularly important for higher performance hatchbacks, saloon cars and sports card.

Important notes on increasing wheel and tyre sizes

There are many instances where drivers are considering increasing their wheel and tyres size for looks or performance, or may have purchased a car with larger wheels.

Whatever the case, it’s important to bear the following in mind:

• Oversize wheels may rub the front wheel arches when the wheels are turned to full lock
• Oversize wheels may hit the rear wheel arches if the vehicle goes over larger bumps
• Oversize wheels will change the rolling circumference leaving your vehicles speedometer out by as much as 6 mph at 50 mph so beware.

Whenever larger diameter wheels are fitted, reduce the profile on the tyres to try are keep the rolling circumference as close to the vehicle manufacturers recommendations as possible.