@rareone : Spacers are small round "washer" type fitment between the RIMS and the wheel hubs. This essentially brings the tyres slightly outwards thus preventing scraping the arches incase u have a upsize tyre. The alignment has to be done keeping the spacers in mind as they change the suspension geometry.
there are pluses and minuses to this ...
+ The broader footprint on the road means the car corners better feels wee bit more stable.
+ Steering feels slightly heavy (maybe its just me)
- The huge back spray that comes on the sides if u are going over water and dirt. Major drawback as i like my car clean.
Got this from a Website
[FONT=Verdana][SIZE=2]What Wheel Spacers Do:[/SIZE][/FONT]
[FONT=Verdana][SIZE=2]Wheel spacers move the wheel out from the hub, effectively widening the stance of the vehicle and lowering its roll centre. This simple modification increases lateral stability, which in turn provides improved handling, greater safety and of course, the sleek style you’ve been looking for. Depending on vehicle make and model they are available for most domestic and imported automobiles. [/SIZE][/FONT]
[FONT=Verdana][SIZE=2]Wheel spacers are also used when a cars such as: Mitsubitsu 3000GT / GTO, Peugeot 406's or some Alfa Romeo's (to name a few) have upgraded brakes, and want to fit aftermarket alloy wheels on, but the larger brake callipers prevents this by coming into contact with the alloy wheel. Other customers of ours needs wheel spacers when they have used brake upgrade kits such as Brembo products. As our fully trained staff deal with such issues on a day to day basis we have unique expert knowledge in this area, unlike other companies who sell wheel spacers. Make sure you deal with a professional knowledgeable company when purchasing alloy wheel spacers.[/SIZE][/FONT]
[FONT=Verdana][SIZE=2]Please have a look at the diagram below which outlines what alloy wheel spacers can do:[/SIZE][/FONT]

[FONT=Verdana][SIZE=2]Original track (offset +43) [/SIZE][/FONT]

[FONT=Verdana][SIZE=2]Fitted with TRAK+
Spacers (offset +18)[/SIZE][/FONT]

[FONT=Verdana][SIZE=2]Track increase available from 10 mm - 90 mm[/SIZE][/FONT] [FONT=Verdana][SIZE=2] Offset Smaller[/SIZE][/FONT]

[FONT=Verdana][SIZE=2]Offset Wider[/SIZE][/FONT]