The number referred to in the code is the tyre's load rating. 96 is rated to 710kg, while 87 is rated to 670kg.

The tyre load capacity should be in accordance with the minimum requirements and sufficient for the axle's presented weight. You can check the axle weight of your vehicle on the axle weight plate, which you'll find either under the bonnet or on the passenger door jamb. The combined load rating of your tyres should equal or exceed this figure. Your insurance may be invalidated in the event of a claim if your tyres do not meet these requirements.