Extensive testing shows that tyres with a Continental minimum-recommended tread depth of 3mm stop in a distance of 91m from 70mph.
With a legal-minimum tread depth of 1.6mm, it takes 135m to stop from 70mph - that's a difference of 44m.
More worryingly, the car on 1.6mm of tread would have been travelling at 50mph when the car with tyres at 3mm would have stopped.
Check your car tyre tread depth with a simple tread depth gauge, available from most garages or motoring retailers.
Make sure you check the tyre in three different places in the main grooves of the tyre and check all four of your car's tyres, as they may wear differently.
If you don't have a tread depth gauge, use a 20p piece: simply place the coin in the groove of the tyre and if you can see the outer edge of the coin, it means your tread depth is less than 3mm and you should consider replacing that tyre.
Less than 1.6mm tread depth is both illegal and dangerous.
Getting caught with car tyres that have less than 1.6mm tread depth could cost you up to 3 points on your licence and a fine of �2,500 per tyre.