New tyres
New tyres fitted where the car is parked
Having new tyres fitted at the car saves a trip to a tyre centre and a wait in a reception area. The work is the same as in a workshop: the old tyre comes off the rim, the new one goes on, the wheel is balanced and refitted, and the nuts are tightened to the maker's torque figure.
Budget, mid-range or premium
Tyres fall roughly into three tiers. Premium brands usually stop shorter in the wet and often last longer; budget tyres cost less up front but vary more in quality.
The label on most new car tyres grades wet grip, fuel efficiency and outside noise, which is a fairer guide than the brand name alone. For a car doing high mileage or plenty of motorway driving, look at the wet grip grade first.
One tyre, a pair or all four
One new tyre is fine when the others still have plenty of tread and match it in size and pattern. A big difference in tread depth across one axle makes the car brake and corner unevenly.
Four-wheel-drive cars are more sensitive to differences in tread depth between tyres, so check the handbook before replacing just one.
Signs a tyre is due for replacing
Tread close to the legal minimum is the obvious sign, but it is not the only one. Fine cracks that open up when you squeeze the sidewall, a bulge, exposed cords or uneven wear on one edge all mean the tyre should be looked at.
Tyre safety groups suggest thinking about new tyres at 3 mm of tread, because stopping distances in the wet grow noticeably below that depth.
Pressure sensors and run-flats
Many cars have a tyre pressure sensor fitted inside each wheel, usually on the back of the valve. Mention it on the call, because the sensor stays with the wheel when the tyre is changed.
Cars that left the factory on run-flat tyres usually need run-flats again, and run-flat and standard tyres should never be mixed on one car.