Volvo 850 Manual page 89

A tread wear indicator is a section of the tread
with a shallower groove and is incorporated into
each tyre. The tyre should be changed as soon
as this section becomes clearly evident, thus
showing that only 1.6 mm tread thickness is
left. Tyre treads below 1.6 mm have very poor
grip in rain or snow.
Maintain correct inflation pressure.
Drive smoothly. Avoid fast starts, hard cornering and heavy
braking.
Remember that tyre wear increases with speed.
If you are rotating the wheels keep them on the same side as they
were so that they revolve in the same direction as prior to rotation.
Correct wheel alignment is very important.
Balance the wheels if necessary.
Do not scrape the tyres against the kerb when parking.
All tyres become warm during use. On cooling, when the vehicle is
parked, the tyres have a tendency to distort slightly forming flat
spots. These flat spots can cause vibrations similar to the vibrations
caused by unbalanced wheels. They do however disappear when the
tyre warms up. The tendency to form flat spots depends on the type
of cord used in the tyre. Remember that in cold weather, it takes
longer for the tyre to warm up and thus longer for the flat spot to
disappear.
In winter, we recommend that you use 185/65 R15 winter tyres on
steel rims (includes 850 turbo).
Use winter tyres on all four wheels.
NOTE! Certain wheel rims from other Volvo models may be used.
Ask your Volvo dealer for further information.
Studded tyres should be run-in for 300-600 miles (500-1000 km)
Wear indicator exposed.
during which the car should be driven as smoothly as possible to give
Tyre is worn. Replace.
the studs the opportunity of embedding properly in the tyres. The car
tyres should have the same rotational direction throughout their entire
lifetime. In other words, if you wish to switch the wheels around, make
sure that the same wheels are always on the same side of the car.
Snow chains may only be fitted on the front wheels and only in
combination with certain Volvo approved wheel/rim combinations. The
chains must have fine links and they should not project markedly from
the tyres as this could cause them to scrape against the brake calipers,
spring strut or other components.
To avoid this, we do not recommend the use of conventional snow
chains on 205/55 R15, 205/50 R16 tyres or tyres of the same width or
wider. Volvo has approved snow chains for all Volvo approved
wheel/rim combinations, with the exception of 17" rims.
Note: Never exceed 30 mph (50 km/h) if snow chains are fitted.
Do not drive with snow chains on bare road surfaces since this causes
considerable wear on both the snow chains and the tyres.
Never use grip links since the space between the brake discs and the
wheel rims is inadequate.
Special wheel rims
The only approved "special wheel rims" are those which have been
tested and approved by Volvo. Ask your Volvo dealer if in doubt.