If you have a sports car or would like to improve the look or handling of your car, adding new wheels could be a good investment. there are different types of wheels available in the market ranging from cheap replica made in Taiwan to really expensive wheels such as BBS. Before you start looking for new wheels you need to answer some important questions -

1. What is the end goal? Is it performance or just looks?
2. Ease in maintenance for new wheels.
3. Are you going to use them all year around or just for winter or summer?
4. What is the price I am willing to pay?
5. What is the current size and offset of the wheels on the vehicle?

Before we explore answers to these questions, let's understand different type of wheels out there.

One of the most common wheel you can find is a steel wheel, they are cheap but heavy at the same time. Next step up is aluminum or alloy wheels, they come in two flavors - cast and forged wheels. Cast wheels are manufactured by melting the metal(either aluminum or alloy) and pouring it in a die cast to form the wheel. Cast wheels have good finish as well as decent structure integrity. However, their quality can vary a lot based on the actual process of manufacturing as well as the manufacturer itself. A good example is some very cast alloy wheels on ebay.They are cheap but there is a reason for it. If you have deep pockets and can afford to spend a little more then next choice would be forged wheels. Forged wheels are made using a aluminum or alloy billet and then stamping the billet to carve out the wheel. Forged wheels are lighter and unmatched in structural strength. Both cast and forged wheels are available in various surface finishes such as clear coat, painted, chrome, polished etc. vehicle.

Now going back to original questions -

1. You need to know the purpose of buying a new set of wheels up front. Is it replacing damaged factory wheels or is it beyond that? If you're replacing a single damaged factory wheel, your local dealership is the place to go. Or may be ebay, if someone has one available for your vehicle. If it is ebay, take a close look at the pictures. There might be a good reason why someone is selling "just one wheel". It might be damaged like yours so it could be waste of money. If your goal is to improve performance, wheel size and weight are the primary considerations. To understand the effect on performance and handling, let's dig through some physics. If you have had any exposure to physics in school or college, you know that anything that rotates, has rotational energy. This energy is directly proportional to the square of the radius and rotational speed. Also, mass distribution around the center of rotation will dictate how emery is stored. Bottom line - you would like to have the mass or weight as far away from center as possible to improve handling. That's why 18" wheel handles better than 16" for the same weight. Same is true for the lighter wheel, a lighter wheel accelerates quickly and will help improve the performance of your vehicle.

Sometimes wheels are referred as +1, +2 sizes, you need to understand that terminology. If your vehicle has 16" wheel as factory OEM, +1 for your vehicle will be 17" and +2 is 18" size.

larger sizes such as +19" and +20" are mostly for show and may not necessarily improve handling. On the other end, you're more prone to damage caused by pot holes or bad road conditions. On most cars , for performance and handling 18" is ideal size.

2. Ease in maintenance is sometimes a big factor too. If you bought a really nice set of wheels but can't keep it clean due to a spoke design, it won't serve purpose as far as looks go. Also some wheels such as painted wheels are easy to clean compared to others.

3. This question tackle the usage question. If you're buying set for winter driving, you could possibly buy steel wheels or a cheap alloy set.

They are going to be dirty in mud and snow so cleaning them often might not be an option. But if it is a summer wheels set, you probably want something that's light and looks good.

4. Your budget. Well, your budget is probably going to dictate what you buy anyway so why not give some thought to it. If you're willing to spend $600, can you stretch a little and go up to $750? These are the type of questions you have to answer. Bottom line is to have some flexibility in your budget so that you can choose from a broader selection. Also remember Forged wheels are more expensive that cast alloy wheels so if you have a budget that only can buy you cast wheels, there is no reason to look forged wheels.

5. Last question is probably the most important one. If you bought a wheel that would not fit on your car, you're in big trouble. So understand wheels offset, width and size before you look for your next set. Or you could go to some online retailers such as Tirerack and pick a set by your vehicle model and type and take all the fitment issue out of the equation.

Wheels and Tires Fitment Guide

Plus sizing your wheels and tires is the best way to improve both the performance and appearance of your vehicle. By using a larger diameter wheel with a lower profile tire it's possible to properly maintain the overall diameter of the tire, keeping odometer and speedometer changes negligible. By using a tire with a shorter sidewall, you gain quickness in steering response and better lateral stability. The visual appeal is obvious, most wheels look better than the sidewall of the tire, so the more wheel and less sidewall there is, the better it looks.

First thing you need to understand is the wheel offset- The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types.

Zero Offset - The hub mounting surface is even with the centerline of the wheel.
Positive - The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.
Negative - The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.

If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. If your wheels is too wide and of incorrect offset, it would rub the fender wall and would damage the wheel, tire and your vehicle body work.

Wheel size is specified as A"XB" where A is the wheel diameter and B is the width. For example 18"X8.5" relates to a wheel that is 18 inches in diameter and 8.5" inches in width. On the other hand tire specifications are usually printed as 225/50R16 91S.

Let's start with - P 225/40 R 17 90 H

The letter in front indicates service type. Fro example P 225/40 R 17 90 S indicate letter P. it signifies the tire is a "P-metric" size that was designed to be fitted on vehicles that are primarily used as passenger vehicles. This includes cars, minivans, sport utility vehicles and light duty pickup trucks.

Next number 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel. This measurement is also referred to as the tire's section width.

Next number is sidewall aspect ratio. typically following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio. P225/40R 17 90 S The 45 indicates that this tire size's sidewall height (from rim to tread) is 45% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The higher the number, the taller the sidewall; the lower the number, the lower the sidewall. We know that this tire size's section width is 225mm and that its section height is 45% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 45% (.45) we confirm that this tire size results in a tire section height of 3.987". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 2.2-inch taller sidewall.

Next letter(R) indicates radial tires(steel belts).

Last three characters (90 S) are the Load and speed rating of the tire.