Whilst many people view the wheels as a purely cosmetic addition to a car they actually have a profound impact of the handling. We shall look at the pros and cons of fitting alloy wheels to a car.
Steel wheels that come with cars tend to be quite heavy and are usually solid, save for a few holes cut in. Having something heavy spinning around takes more energy that something lighter. Also having a heavier unsprung mass means the car will be less predictable on rough surfaces.
The brakes main job are dissipating the heat. If they are housed in what is effectively a steel drum they will be unable to do this as effectively.
So alloy wheels or if we correctly name them, magnesium alloy wheels, are the potential solution. The alloys are generally lighter than their steel counterparts and allow larger air holes.
For most effective brake cooling go with a set that has a double row of holes around the outside of the wheel such as those produced for rally cars by OZ and compomotive.
Larger wheels will usually impair the drive and ride quality of the car so you should endeavour to maintain the same rotational diameter. If this diameter is larger then the speedo will under read so recalibration will be required. Problems of larger wheels include tramlining, poorer cornering and as the final drive ratio is altered the acceleration will also be worse.
One method to maintain the same rotational diameter would be to fit lower profile tires (we will look at these in another article) but they will help to reduce the circumferance of the wheel back to OEM specifications.
Wider wheels will improve grip and cornering ability as you have a greater contact areas. When you change the wheels you should always get the tracking, camber and toe reset to avoid premature tire wear.
Suspension kits
The biggest impact on a cars handling performance is the suspension. The main parts of a suspension package are a spring and a damper (sometimes called a shock absorber although this really describes the whole thing.)
Springs control the ride height of a the car and determine the amount of road bumps that are absorbed. A stiffer spring is more resistant to movement and a softer spring will allow the wheels to better follow the undulations of the road surface.
Generally the lower the better. A car that is low has a lower center of gravity and axis of movement. This allows faster cornering. We need to bear in mind that whilst tracks are perfectly smooth our roads are not. A low car will often grind the sump of the engine on speed bumps and the ride quality will be seriously compromised on rough surfaces.
For road cars then we recommend that you fit a slightly stiffer spring. If the coil size decreases this will help to maintain the amount of travel and allow you to achieve a good balance between comfort on the road and good handling.
The damper is what prevents the car from jumping and bouncing up the road by absorbing as much of the vertical motion of the wheel as possible.
A damper is a cylinder filled with oil or filled with gas and oil with a piston that moves inside the cylinder. The friction of the fluid will create the damping effect. If the damper is too soft the car will start to bounce and wallow. If it is too hard the car will skip over bumps. Again a careful balance is needed. The uprated shocks with gas and oil are a good compromise as the gas layer allows for some compression and the oil maintains the friction required.
When lowering and uprating a cars suspension you should always go for an fully adjustable suspension kit. Each car and indeed each driver is unique. You ideally will adjust your handling to suit your personal driving style.
