Although there is no legal restriction as to how old a tyre can be, Tuev, a German safety inspection agency, advises drivers to buy new tyres at about the six-year mark. The elasticity agents in a tyre's rubber mixture break down over time, which leaves the tyre brittle and not in optimal condition.
A tyre's age can be determined by the four-digit DOT number, which can be found along its side. The first two digits indicate the week and the last two digits the year of production – in other words, a tyre with the DOT number 4312 would have been made in the 43rd week of 2012.
While the legal minimum tyre tread depth in some jurisdictions is around 1.6 millimetres, Tuev recommends treads at least 4 millimetres deep for winter tyres.
Regardless of whether they are new or old, all tyres need to have the right air pressure. Drivers can find indications for proper air pressure values in their car's operating instructions, along the inside of the driver-side door or on the fuel tank cap.
Remember to pay attention to the different values needed when carrying more weight in or behind the vehicle.
Anyone who wants to change their tyres on their own should use a torque spanner and consult their owner's manual to find the correct tightening levels.
If a bolt isn't fastened tightly enough, the wheel could come loose, while turning the spanner too tightly could or strip damage the wheel's bolts.
After the first 50 to 100km mmediately following the tyre replacement, Tuev recommends retightening the bolts.
