Finding the Correct Tire and Wheel Combination for Your Vehicle
Aftermarket wheel and tire combinations are one of the most popular choices for the enthusiast looking to upgrade the look of their car, truck, or SUV. However, with so many wheel and tire sizing options many people have trouble getting it just right. Compiled and discussed by our lead technician, here are a few key guidelines to follow when shopping for wheels and tires.
1. Size Matters!
When replacing your factory wheels and tires it is always more appealing to ‘size up’ your wheel and tire combination? A larger wheel/tire diameter fills out the wheel well for a sportier, cleaner look. A wider tire not only increases the effective contact patch on the pavement, but also gives a vehicle a wider, more aggressive stance. Be wary of tire and wheel combinations that are too large! Installing oversized wheels and tires is a dangerous game because without suspension modification, the tire itself can rub on any number of surrounding parts of the car. A tire that is too large in diameter can rub on the edges of the fender well when turning or encountering large bumps or dips in the road. A wheel with an extreme offset or backspacing, or a tire that is too wide can rub on the frame, steering, or suspension components causing premature tire wear or component failure. The desire to ‘Go Big or Go Home’ can leave you going home in a noisy vehicle with a costly repair bill.
2. Watch Your Back…spacing and Offset
In general it is best to stick with a backspacing and offset that closely resembles that of your factory wheel. On passenger cars components such as brake calipers, ABS sensors, and suspension arms come in very close proximity to the inner surfaces of the factory wheel. Installing or attempting to install wheels with a backspacing or offset that is much different from the factory setup can cause the inner surfaces of the wheel to contact these components. Premature wear and failure of these components as well as the wheel itself can occur, as well as an undesirable noise in the passenger compartment.
Wheels manufactured for trucks and SUVs have a much wider offset and backspacing to accommodate larger braking systems, wider wheelbases, and four wheel drive components. It is sometimes popular for truck and SUV enthusiasts to purchase wheels with a significantly wider offset and backspacing for an extremely wide stance. While this can look great and increase the handling of the vehicle it is easy to get carried away. Many people don’t realize that this can also cause tire rub. Basically the farther out from the hub centerline that the wheel extends, the wider the arc that is created by the front wheel as it turns from side to side. If this arc is larger than the diameter of the wheel well, the tire will rub on the outer edge of the fender lip or the inner surface of the wheel well liner.
An even less commonly accepted but still important issue can arise with wheels that have an extreme offset and backspacing. The laws of physics tell us that the farther out on a supporting boom a load is extended, the more force is in turn exerted on the fulcrum of the boom itself. As it applies to our conversation this means that the farther out from the wheel hub the weight and body of the wheel extends, the more force is exerted on the hub itself. This can mean damage over time to the lug studs, ball joints, and hub bearings as well as increasing the risk of damage to the wheel.
3. Get Everything You Need the First Time
Once you have picked out a wheel and tire combination that works for you, YOU’RE NOT DONE YET! In addition to the basics, there are a few items that you will need to get the job done. The most important item to remember is a set of lug nuts. Sometimes the factory nuts will be compatible with aftermarket wheels, but this is not something you can count on. Factory lug nuts are often too large for aftermarket wheel lug wells, as well as showing an unsightly contrast to a shiny new wheel. There are a myriad of aftermarket lug nut styles available, and you should choose a style that not only works well with your wheel, but also compliments its looks. Things to keep in mind are thread pattern and thread pitch, socket size, seat style, and overall length. Examples of some common lug nut styles are shown below.
In addition to the necessary hardware there are a few operations that need to be performed on newly mounted wheel and tire packages. Every wheel must be balanced once a tire has been installed on it, new or used. Balancing involves placing weights on the wheel at specific locations to eliminate any difference in the rotational mass of the mounted wheel and tire. Valve stems must also be installed on all wheels before tires can be mounted.
Here at Film At Eleven, we include valve stems, wheel weights, and balancing in our labor charges, which will be listed clearly on your invoice at the time of final checkout.
At Film at Eleven, we take four-wheeling and performance seriously. We are the premier accessory shop for all your off-road, performance, lighting, and stereo needs. We will install our parts or yours from lift kits, lowering kits, grill guards, custom bumpers, winches, exhaust systems, lockers, ring and pinions, lighting, and audio.
We can align your vehicle also, even lifted or lowered cars and trucks.
We sell and install new and used toppers and new Tourneau covers.
We sell and install wheels and tires for both cars and trucks and can even diagnose and replace TPMS (tire pressure monitor system) sensors.
Our window tint professionals are second to none, and offer a lifetime warranty on our Solar Gard Window Film and installation.
With over 30 years of experience installing car audio systems, we know our stuff. Whether you’re looking to win the ultimate car audio competition, or if you want to just cruise around and enjoy the music, let us help you design the perfectly custom system for your vehicle. We’ve got headsets and amplifiers, we’ve got speakers, bass and subwoofers, we’ve got what you need for your ride.
Adding electronics to modern day vehicles has become a challenge for the 12 volt industry, but our experienced technicians have the ability and resources to tackle almost any vehicle. We stay current on new developments so we can integrate your audio, video, remote start, cruise control, backup system, or alarm seamlessly into your vehicle. Film at Eleven’s professionals can install replacement leather for your seats, heated seats, seat covers, new headliners, and many other interior items.
Our team of professionals have over 75 years of combined experience to give you peace of mind when working on your vehicle.
Performance and Economy General Information
Automotive Physics 101
Don’t let the title scare you away! We want to educate our customers about the science behind automotive performance and fuel economy without making it complicated. To begin with we will go over the basic ins and outs of today’s automobiles and what effects different variables have on how they perform. Then we will show you what we can do at Film At Eleven, Inc. to optimize your vehicles performance AND economy for your needs.
Lesson #1: The Internal Combustion Engine
The cornerstone of today’s vehicles is the internal combustion engine, a machine that is engineered to convert energy created by a chemical reaction (in this case the burning of fuels such as gasoline and diesel) into mechanical energy to make the vehicle move. Below is a diagram of a traditional engine design today and how it fundamentally operates.
The important thing to remember here is that the rotation of the crankshaft is what eventually turns the wheels. Sure there’s a transmission, driveshaft, u-joints, bearings, seals, gears, and half shafts in between but that’s not the point. We’re sticking to the basics here. As the pistons cycle back and forth in sequence they produce enough force to move even the largest and heaviest vehicles.
Lesson #2: Engine Efficiency and Fuel Mileage
Now that we have a basic understanding of the action behind the scenes, we can focus on the aspects of this action that determine how an engine will perform, and how efficiently. Take a look at the combustion chamber in the first of the two diagrams. The small blue and red dots represent an airborne mixture of fuel and oxygen that is being pulled directly through the vehicles intake system. Because the air/fuel mix is an airborne cloud it behaves somewhat like a gas, especially once it is compressed by the piston. Physics tells us that a gas will expand to fill any container it is put into, therefore a larger combustion chamber will hold (and burn) more fuel. This is the most influential aspect of the fuel consumption and efficiency of an engine. Now imagine that we could increase the number of those dots without increasing the size of the combustion chamber, and how easy it is for the engine to pull them in. With more fuel and oxygen readily available for combustion we have a more powerful, more efficient engine. This is one of the key factors that determine that most talked about rating, Fuel Mileage. Efficiency and fuel mileage are synonymous in our little study, meaning that they are directly related and the higher your efficiency the higher your fuel mileage.
Lesson #3: Power to the People
Since we obviously have no control over how large the combustion chambers are in a particular engine aside from buying another car, you may think that there is nothing you can do to make your car more efficient or more powerful. In essence this is true because the design of the engine itself determines the power and efficiency it is capable of. What most people don’t realize is that the engines in most passenger cars and trucks are not optimized for power and efficiency. You’re probably saying to yourself “How can they get away with that!?” Due to restrictions on emissions, noise, and power output automotive companies must include mechanisms for reducing them. Many times these additional parts or design changes make the engine less capable of reaching its peak operating efficiency. That’s where we come in! Film At Eleven, Inc. has a wide range of parts and accessories to increase your power and fuel mileage. Let’s take a look at some solutions that we offer to improve your experience on the road AND at the pump.
High Flow Air Filters and Intake Systems
Replacing your vehicles factory air filter or intake system is one of the least expensive modifications to make to improve power and efficiency. High flow filters are made out of high quality materials that allow your vehicles engine to breathe better, increasing the amount of available oxygen to the combustion chambers. The difference between the two is simple. A replacement air filter increases air flow to the engine using high quality fabrics and wire mesh as a filter material while utilizing your vehicles factory intake system ducting. An aftermarket intake system builds upon this concept adding large diameter, low resistance ducting to a high flow air filter as well as eliminating noise reduction devices that actually slow air induction into the factory intake system. For most vehicles adding a high flow filter or intake system shows real gains in horsepower and fuel economy when tested on a dynamometer and on the track.
Wheel And Tire General Information
The arrangement of holes surrounding the center of the wheel that allows it to be bolted to the hub. Differences in vehicle make and model determine how many holes there are and the diameter between them. This is the most important information to know about your car when replacing your existing wheels, as only one bolt pattern will work on any given vehicle.
Back Spacing (Rear Spacing)
The distance from the surface of the wheel mounting pad to the outer edge of the wheel flange. Back spacing is typically different for cars than it is for trucks. It is often important to know what backspacing your vehicle can accommodate when shopping for aftermarket wheel and tire packages.
The distance from the vertical centerline axis of the wheel to the wheel mounting pad. Offset is also an important factor to consider when buying an aftermarket wheel. When combined with back spacing, an extreme positive or negative offset can cause problems with wheel fitment or tire rub.
To find offset reference the width and the backspacing of your wheel on the table above.
The inside diameter of the center hole in the wheel. Certain cars have a raised hub center and their factory wheels are machined to fit snugly around it as a more stable method of wheel centering. Such wheels are called ‘hubcentric’ and will not fit on certain other vehicles with larger hub diameters.
The letter or letters preceding the numbered size codes indicate the type of vehicle and recommended usage for the tire. Some common service types are:
- P – Passenger. Used primarily on cars, minivans, SUV’s and light trucks
- LT – Light Truck. Used primarily on light to medium duty trucks, SUV’s and ORV’s
- T – Temporary. Indicates a tire that is to be used only as a spare until a failed tire can be replaced.
- C– Commercial. Indicates a tire that is rated for vehicle that carry heavy loads. (see Load Range below)
- ST – Special Trailer. Used only on boat, car, or utility trailers.
A three digit number that represents the total width of a mounted, inflated tire at its widest point from the outer sidewall to the inner sidewall. Using the metric system, this dimension is measured in millimeters (mm).
Sidewall Aspect Ratio
A two digit number following the section width that represents the height of a tires sidewall as a percentage of the section width. In the example above the tire has a section width of 205 mm and the sidewall is 70% as tall as the tire itself is wide. The combination of the sidewall aspect ratio and the section width are the most important determining factors of the actual dimensions of the tire.
Internal Construction and Speed Rating
The letter or letters following the sidewall aspect ratio indicate the type of materials that make up the tire itself and the speeds at which the tire will safely perform. Most tires on the road today have a ‘radial’ construction, hence the letter ‘R’. Some tires are rated with the letters ‘D’ or ‘B’ to signify diagonal (bias-ply) or belted construction. A tires speed rating indicates the maximum speed at which a specific tire can operate safely without losing grip on the road or coming apart due to excessive centrifugal forces.
Wheel and Tire Diameter
The final letter in the sequence represents the total diameter of the tires mounting bead. This measurement must match exactly the total diameter of the wheel.