Wheels and Tires Are Cool!

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Aug 4, 2001

Wheels and tires are some of the most commonly upgraded parts on a car. This is because a different wheel and tire package can dramatically improve the looks and even the performance of your car for a relatively low cost. However, there are a number of key points that any perspective wheel and tire buyer should be aware of.

The first is that the wheels and tires have to fit. Alright, while this may seem blatantly obvious, not any wheels and tires will fit on any car. All wheels have a bolt pattern that must also carry over to any aftermarket wheel you are looking at. For example, many late-model Hondas have a 4X100 bolt pattern (the 4 refers to number of bolts and the 100 is the diameter across center of the bolts). Thus, any new wheel that you buy must also have that same 4X100 bolt pattern, or it will not fit properly. Also, you can’t go overboard and put 20in wheels on a Civic. It might be possible, but it would require a great deal of extra work and money. For most applications, a Plus-2 or 3 wheel will be more then enough for the buyer, meaning that if you have 14in wheels, anything past 17in wheels might require some work in order for it to fit. It is also important for the new tire’s diameter to stay similar to that of the stock tire, otherwise the speedometer will be slightly off. You can find the diameter of the stock tire on the sidewall, where a set of three numbers will be listed, such as 205-65-15. The diameter is 205mm across the tire when it is unloaded, so try not to increase that too much with your new wheel and tire package (for reference, the 65 is the height of the tire sidewall and 15 is the size the wheel designed to fit the tire). So now that you know what wheels and tires fit well with your car, how do you actually go about picking the right ones?

Almost any time you increase the size of your wheels, you will also increase weight of your wheels. That’s simple. However, what isn’t so simple is what more weight can do to your car’s handling and acceleration. The first term you have to know to understand wheel weight is “unsprung weight.” This is defined as weight that is not suspended/sprung by the car’s suspension (the wheels, tires, brakes, hub, calipers, etc). It is always best to buy the lightest weight wheels available, because the lighter the wheel, the less work the suspension has to do in order to turn and go through its normal motions. This can improve handling, and lighter weight wheels can also help your acceleration. This is where the second term you need to know comes in: “rotational inertia.” Lets say that your car has 14in wheels and you want to upgrade to a set of 17s. These wheels will almost always weigh more then the original 14s, and will not allow as much of the car’s power to reach the ground. This is because the engine has to do more work accelerating the heavier wheels then accelerating the car itself. But how much weight is too much? A good rule of thumb is that any wheel that weighs over 30 lbs. is too heavy, and will result in decreased performance. Larger wheels can also improve the looks of your car as well, but that is not a matter of science like unsprung weight or rotational inertia, but rather matter of personal taste. So now that you have some wheels that will fit your car and are light in weight, what do you do about tires?