Vehicle performance can be improved without
the necessity of changing wheels simply by selecting a tyre with a
lower profile. This means maintaining overall diameter while lowering
aspect ratio and correspondingly increasing the tyre width. Put simply,
a tyre with a lower section height and wider tread has better cornering
force and grip, thus improving steering stability.
In order to attain the maximum performance
out of your vehicle, larger and wider wheels are recommended. Although
high performance is our goal, there are certain safety guidelines
that must be observed. This means that wheel size and type, and tyre
height and width must fall within certain limits.
When selecting a high performance tyre
the following must be observed.
Clearance
Wheel well clearance must be maintained. Failure to do so would most
likely severely cut the tyre when turning, if not lead to a puncture.
The vehicle manufacturer can provide the maximum tyre width permissible.
Otherwise consult a specialist high performance
tyre dealer.
Speedometer Error
With a constant wheel diameter, overall tyre diameter will decrease
proportionately with aspect ratio. This smaller overall diameter
will result in speedometer error.
Wheel Selection
It is often the case that new wheels are required. This can be because
either a larger rim width and/or larger rim diameter is called for.
When choosing high performance wheels ensure that they have the
correct offset and pitch circle diameter (P.C.D.) for your vehicle.
Up Stepping to High Performance
Maximizing your car's performance by selecting a lower profile tyre/larger
size rim combination is referred to as "up-stepping."
Plus-one or plus-two tells you how much larger the rim size is.
This "up-step" approach to improving performance came
into being because, although it is possible to get higher performance
without changing rims, it is often necessary to increase tyre width
to the point that steering geometry is affected, with the result
that a change in driving style or habits becomes necessary.
So to fully maximise
your vehicle's performance (which includes preserving the steering
geometry) the "up-step" approach is highly recommended.
By fitting a larger rim, increases in
tyre section width are properly managed while correct overall diameter
is maintained. This maximizes cornering force and grip without sacrificing
any other handling parameters.
