More than 30% of parents are ferrying their most precious cargo around on illegal tyres, a new study has found.

Road safety charity TyreSafe has reported that one of its members carried out a study at a Shropshire primary school, where almost a third of the cars dropping children off at school had tyres that were either past their wear markers, were incorrectly inflated, had bulges or cuts or had foreign objects sticking out of them.

Stuart Jackson, chairman of TyreSafe, said: “The start of the new academic year means that we will be experiencing many more cars on the roads, particularly at peak times of the day.

“Many of these cars may be used less frequently so it’s essential that their tyres are checked to ensure that they are roadworthy and legal so that children are transported in a safe manner.”

According to the charity Sustrans, more than 11 million car journeys are made between home and school every day.

Meanwhile, Department for Transport figures quoted by TyreSafe show that more than 1,200 road casualties are caused each year as a result of a car travelling on illegal, defective or under-inflated tyres.

Ahead of the return to school, TyreSafe is encouraging parents to check that tyres are inflated to the vehicle manufacturer’s recommended settings, which can be found in the vehicle handbook, inside the fuel filler cap or on a plate on the driver’s door sill.

Secondly, tread depths should exceed the UK’s minimum legal depth of 1.6mm across the central three-quarters of the tyre, around its entire circumference. Non-compliance could lead to a tyre-related accident, a fine of up to £2,500 and three penalty points for each illegal tyre.

Finally, the general condition of the tyre should be inspected to ensure they are free from lumps, cuts and bulges. Any foreign objects in the tread should also be removed