Jeep Wheels - which is best for you?

Steel or Aluminum Alloys, which is best for you?

While ultimately it's your own choice, each offers some distinct advantages. Steel wheels are tough and cheap. easily repaired on the trail, they can take a beating and still get you home. Aluminum alloys wheels offer weight savings allowing better tire control, better ride quality and many can still handle a beating. being an aluminum rim back into shape enough to hold air is possible, though the rim will need replacing and will usually break when you try to bend it back, so this is a short term fix only.

So, steel or aluminum alloy - let's look at each in a bit more detail.

Steel Wheels

Most genuine wheels are made of steel. An stamped inner part is joined to a rolled outer rim and nowadays welded together. If you look at older rims on Willys you can still see that they were riveted together. The setup is strong, easy to repair but most important, cheap to fabricate. They can be painted over and over again if years of off roading take their toll. Many manufacturers use the same production method but take stronger and/or thicker materials to increase load capacity and they also make them in sizes better suited to aftermarket tires. The biggest disadvantage of steel is it's weight or better it's lack of performance. An aluminum or alloy wheel will accelerate faster and stop quicker as well as reduce load on shocks and steering linkages. How can such a rather small weight difference make up for a drastic change you may as? After all the difference will rarely exceed 8 pounds per wheel. This would be true in a static situation.

But the wheel is a dynamic part on the Jeep. Its weight must be accelerated and slowed; its movements must be controlled. And everyone familiar with physical laws can tell you that a moving part's inertia is completely different from a static part as the rest of the axle is.

There's a tremendous amount of force stored in a rotating wheel. You need lots of power to get it up to speed and you need also good brakes to slow it down. The steering linkages will wear faster too. The heavier a wheel/tire combo the more energy is needed. The same principles apply for your shock absorbers. If you have a heavy wheel your shocks and steering will take a beating, so aim for the lowest possible weight.

A steel wheel will also bend much earlier than an alloy wheel. But you can hammer a steel wheel back in shape while an alloy wheel will usually break. So if you intend to do many miles far away from civilization keep the steel. If shopping for used rims you can test them by mounting them and holding a pencil or similar against the edge and rotating the wheel. This runout (think of it as wobbling from a flat plane) can be of up to 2-3mm even on new wheels but I'd keep off if it exceeds more than this.

Old military wheels are mostly bent so keep that in mind. This is less of a problem on cars seldom exceeding 80 Km/h. Also, being steel, the wheels may rust to a point where structural integrity is affected.

Aluminum Alloy Wheels

One-Piece Cast Wheels

This is the most common type of aluminum wheel. The casting of wheels is the process of getting molten aluminum inside a mold to form a wheel. Most manufacturers alloy wheel suse this process to get the desired look at a lower price-point, which helps keep production costs in line.

There are different ways this can be accomplished and although it sounds simple, this is truly an art when done properly. Below is a brief overview of the types of castings with some of thewir characteristics.

Types of castings/construction include:

• Gravity Casting

Gravity casting is the most basic process of pouring molten aluminum into a mold utilizing the earth’s gravity to fill the mold. Gravity casting offers a very reasonable production cost and is a good method for casting designs that are more visually oriented or when reducing weight is not a primary concern. Since the process relies on gravity to fill the mold, the aluminum is not as densely packed in the mold as some other casting processes. Often gravity cast wheels will have a higher weight to achieve the required strength.

• Low Pressure Casting

Low pressure casting uses positive pressure to move the molten aluminum into the mold quicker and achieve a finished product that has improved mechanical properties (more dense) over a gravity cast wheel. Low-pressure casting has a slightly higher production cost over gravity casting. Low pressure is the most common process approved for aluminum wheels sold to the O.E.M. market. Low-pressure cast wheels offer a good value for the aftermarket as well. Some companies offer wheels that are produced under a higher pressure in special casting equipment to create a wheel that is lighter and stronger than a wheel produced in low pressure. Once again in the quest for lighter weight, there is a higher cost associated with the process.

• Spun-rim, Flow-Forming or Rim Rolling Technology

This specialized process begins with a low pressure type of casting and uses a special machine that spins the initial casting, heats the outer portion of the casting and then uses steel rollers pressed against the rim area to pull the rim to its final width and shape. The combination of the heat, pressure and spinning create a rim area with the strength similar to a forged wheel without the high cost of the forging. Some of the special wheels produced for the O.E.M. high performance or limited production vehicles utilize this type of technology resulting in a light and strong wheel at a reasonable cost. BBS has used this technology for several years in their production of racing wheels for Formula One and Indy cars.

• Forged or Semi-Solid Forged

The ultimate in one-piece wheels. Forging is the process of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure. This creates a finished product that is very dense, very strong and therefore can be very light. The costs of tooling, development, equipment, etc., make this type of wheel very exclusive and usually demand a high price in the aftermarket. Semi-solid forging (SSF) is a process that heats a billet of special alloy to an almost liquid state and then the aluminum is forced into a mold at a very high rate. The finished product offers mechanical properties very similar to a forged wheel without the high production and tooling costs of a forged wheel. When low weight and performance are on your priority list, the SSF technology offers an excellent value. Currently only SSR (Speed Star Racing) from Japan is licensed to use this process for the production of wheels. They produce wheels only for street applications.

Multi-Piece Wheels

This type of wheel utilizes two or three components assembled together to produce a finished wheel. Multi-piece wheels can use many different methods of manufacturing. Centers can be cast in various methods or forged. The rim sections for 3-piece wheels are normally spun from disks of aluminum. Generally, spun rim sections offer the ability to custom-tailor wheels for special applications that would not be available otherwise. The rim sections are bolted to the center and normally a sealant is applied in or on the assembly area to seal the wheel. This type of 3-piece construction was originally developed for racing in the early 1970s and has been used on cars ever since. The 3-piece wheels are most popular in the 17" and larger diameters.