Basically it’s sensible to check your tyre tread depths, and replace your car tyres before getting towards the wear indication, as at this stage, the efficiency of the tyre while in the wet is rather limited, as well as its grip while in the dry won’t be as well-defined as it was when it was new.
In 2006, Auto Express publication in the United Kingdom performed some pretty extensive assessment on “legal” car tyres. They’re campaigning to get the legalised minimum tyre tread depths in the United Kingdom increased from 1.6mm up to 3mm. Their motives are supported by testing: at 1.6mm, regardless of still currently being completely legal, the stopping range is increased by 40% in the rain, above car tyres which have 3mm of tyre tread depths remaining. They conducted the test with the same vehicle, in the exact same conditions sticking with the same driver. The one thing that altered was the car tyres. The 5th Gear Television show carried out a graphic illustration showing the issue by equipping two vehicles with various car tyres. The lead vehicle had 3mm of tread remaining; the trailing vehicle had 1.6mm. The vehicles had been driven at 50mph at a length of 3 vehicle measures apart – unsafe, but associated with the real-world. Once the lead driver carried out an unexpected emergency stop, the trailing driver responded almost immediately, but in spite of many years of training as well as an ABS-equipped vehicle, he slammed in to the lead motor vehicle still doing 35mph. So check your tyre tread depths!