Wheel Reference Information
WillTheyFit.com - Will They Fit is an online wheel and tyre calculator to help you compare a new set of wheels and tyres against your existing ones to help you get a picture of how they will fit.
Wiki: Wheel Sizing - A guide to many of the factors to be considered in wheel sizing
Wiki: Wheel Offset - Wiki provides some useful information on the topic of car wheel offset.
Wiki: Unsprung Mass - Unsprung mass is just one factor of how a wheel's weight affects a car's performance, but it is an important one.
General Motoring Links
Pistonheads - Pistonheads is probably the largest car forum for petrolheads in the UK.
Parkers - Parkers have a huge database of car reviews and car specifications, but they don't say much about wheel offset.
The AA - The AA breakdown service. If all else fails get the AA to change your wheels for you!
RAC - In the interests of fairness, here's a link to the RAC.
Top Gear - The world famous Top Gear motoring magazine TV show.
Fifth Gear - Fifth Gear, another great motoring magazine TV show.
Car Web Directories
AllworldAutomotive - AllworldAutomotive is a popular links directory with lots of categorised car links.