You will find your speed rating on the side of your Tyre at the end of a series of numbers – MOT requirements in this country stipulate that it is necessary to fit a Tyre with a speed rating to match the original vehicle fitment or the maximum speed of the vehicle. Tyres must be suitable for the purpose for which the vehicle will be used.
Insurance companies might say that a vehicle should be fitted with the Tyres having the speed rating recommended by the car manufacturer but even if you fit Z-rated Tyres for speeds over 150 mph they will not insure you if you drive in excess of 70 mph in this country!
The vehicle manufacturer has to recommend a Tyre with a rating to match the maximum speed of the car because when it leaves the factory they do not know exactly where the car is going or for what purpose it might be used. You might want to use the car in a country where higher speed limits apply than the UK or take it to a race track at the weekend.
The table opposite shows the maximum speed for a Tyre when carrying a full load.