Choice of wheels
There's a little more involved when buying alloy wheels than just the shape and style. Carefully choosing mods for your car doesn't stop at wheels, if your car is extreme than it'll be substantially lowered which means adequate care and attention will be needed when choosing the right wheels for the job. This article explains the technical jargon.
Alloy mag what ?
Race wheels are made from magnesium and titanium but we have to settle for alloy wheels. Race wheels are about 50% lighter than alloy wheels so you can understand why they use them. Our alloy wheels are only 80% aluminium. The remaining 20% consists of other metals such as magnesium, silicium and copper. Enough theory, what's the deal when you buy a new set then ?
Offset
The most important bit is the offset of the wheel (also called ET). The offset of a wheel determines how much a wheel sticks out when installed. To put it simple you'd have to cut your wheel in half mid-width. ET is the distance from the mounting face to the middle of the wheel in millimetres. For example for a Citroën ZX you need an offset of 15, which means that the distance between the mounting face and the middle of the wheel is 15mm. The Golf Mk3 uses an ET of around 35, which means that it sits a lot deeper in the arch.
Spacers
Nowadays more and more wheel manufacturers are producings wheels with only one offset. I had a look recently at OZ and Enkei wheels. OZ could sell me a 17 inch wheel with an ET of 37, Enkei could offer me one with an ET of 35. Pretty useless for a ZX or are they? Enkei could sell me 20mm spacers so that I'd get ET 15, suitable for my car. I don't know about you but I'm not into spacers. The thought of a metal piece sitting between the wheel and hub scares me. Well, I'm not scared anymore because you have to screw the Enkei wheel spacers into the wheel before you mount the wheel. Very handy in case you have a flat tyre. Other spacers are screwed onto the hub first with further threaded holes for the wheel to mount to effectively making the hubs of the car wider. It is also possible using this method to use threaded holes in the spacers that are a different pattern allowing you to mount wheels from a different car, see stud pattern later on.
OZ do a similar system. They had wheels with an ET of 37 but 21mm spacers turned them into ET16, which I think will fit the ZX. OZ uses a system with which the spacers click into the wheels, instead of a screwing system like Enkei. Both are pukka solutions. These spacers aren't free of course and you can expect an extra 100 pounds or so for the spacers and longer bolts. It's not cheap but it is quality stuff. It's worth remembering though that if your arch space is really at a premium you can run a different offset back to front using spacers. You can also adjust the offset for clearance *after* you have bought the wheels if you need to, for example if you go that bit lower.
Stud Pattern
Another problem is the distance between the mounting holes. The holes are drilled equally spaces around a circle of a certain diameter eg 108mm in diameter for most Peugeot wheels and Ford. For Volkswagens, this diameter is 100mm. This is known as PCD - Pitch Circle Diameter and is an engineering term for describing holes around circles. The stud pattern varies from car to car but there are common patterns there which will allow you to fit factory wheels from another make on your car, for example you can fit Ford wheels on a Peugeot if you want using spacers to give the correct offset. Many cars are migrating towards 5 stud, you will see the spec for wheels quoted often as 4 x 108 which would mean 4 holes 108mm PCD. or 5 x 100 is a 5 stud wheel with 100mm PCD.
Decision Time
Then it's up to you to decide what size of wheel you're gonna fit. Are you going German and fit 13 or 14 inch wheels ? Or are you going the monster wheel route and will you try to fit 18's, 19's or bigger ? For the least amount of problems choose something between these extremes like 15's or 16's on most cars, this will also alloy a decent amount of lowering too. Keep in mind that the price of rubber increases with size. A 195-45-16 tyre costs almost twice as much as the common 195-50-15 size.
Pulling Power
You'll also notice that your cars pulls slower if you fit big wheels. This is due to the fact that if your car is setup from the factory to run with 14 inch wheels and you've just installed 18's then even with the ultra low profile tyres you have increased the circumference of the wheel significantly. For example take the 14 inch wheel from the factory and the 18 incher, roll the two along the ground until they have each done exactly 1 revolution, which one has travelled further ? It will be the 18 inch wheel because there is more distance around its edge. This will reduce your acceleration, increase top speed assuming you car can pull the high revs still and your speedo will read a lower speed than you are actually doing. Massively oversized wheels will also adversely affect your handling. My suggestion is not to fit 17 inch wheels if you only have an 1100cc engine. It might look good but acceleration and torque will suffer on little engines - up to you if you prefer more show than go.
Contact Sport ?
Another issue to avoid contact between tyre and arch is the width of the wheel. German nutters place 8 or 9 inch wide wheels on their motors, impossible to tuck away in the arches. If you're going for the touring car look you'd better keep things between 6.5 and 7.5 inch wide, depending on your type of car. As you can see there's more to it than just choosing a shape of wheel. You'd best ask for advice at your wheel suppliers. They'll be happy to tell you what wheels are suited for your car.
Style
That leaves the look. Are you going for a classic five spoke or do you want a six spoke, which are popping up more and more ? Are you gonna have the wheels polished or are you going American and have them chromed ? Whatever you choose, try to be original and don't go for what everyone else has got. Originality is the keyword here. Have fun.