Speed and Load

Load Index and Speed ratings:
The load index generally found on the side of the tyre is a numerical code relating to the maximum load the tyre can safely carry. The table below gives you most of the Load Index (LI) values you're likely to ever need.
To explain simply, if you know your car weighs 2000kg then assume an even weight on each wheel, 2000kg divided by 4 wheels = 500kg per wheel. This is a load rating of 84. Ideally you should add 20% or more for safety's sake, to alloy you a full load of passengers and luggage. Generally speaking most car tyres will have a much higher load rating than you'd ever need. It's safer to have a tyre that will only fail at speeds and load levels you physically can't achieve.

Load Index Table

Speed Rating Table

All tyres are rated with a speed letter. This indicates the maximum speed that the tyre can sustain for constant ten minute period without coming to pieces and destroying itself. Remember the heat build up at the tyres maximum speed is immense, so along with the law this should be another reason not to speed!