F&S Guide to Truck Wheels
Roll through anything the right way with this guide to truck wheels for the outdoorsman.
The hand-drawn map was pinched between my thumb and the steering wheel. According to the smeared lines, I would be able to see the river after the next curve. I had been told that the pullout overlooked a great stretch of pocket water. “Big ‘bows,” my friend had said over the phone. “Even better, almost no one fishes this stretch.”
“Why?” I asked.
“The road is really in miserable shape. A lot of it washed out last winter. Take it slow.”
The road was bad–but when I made the pullout there was one fellow ahead of me. He was shucking his waders as I pulled in.
He nodded, stowed his rod, and then ambled over to talk. “Nice looking wheels,” he said. Then he bent down for a closer inspection. “Aluminum?”
He spat a long stream of tobacco juice. “Don’t care for it. I want a strong wheel. Steel for me.”
Stressful Matters: Like most outdoorsmen, this guy didn’t beat around the bush when it came to opinions on gear. And he certainly wasn’t the first who questioned the wisdom of tackling tough offroad trails on aluminum wheels.
When I got home I tracked down Laurie Simpson, staff product engineer at Alcoa Wheel Products International, and asked her, “Look, I haven’t had any trouble with these wheels, but boy do I catch it when other guys learn I’m driving on aluminum. What gives?”
I could hear Simpson take a deep breath. Obviously, this was a familiar question. “The aluminum forged wheel manufactured by Alcoa is actually stronger and tougher than a steel wheel,” she told me. “The other goodie is that our wheel is about half as heavy as steel. And a lighter wheel gives the vehicle better handling characteristics.
“What many of your guys don’t know is that there are actually three types of aluminum wheels on the market–cast, billet, and forged. Each process leaves the product with certain traits as distinctive as fingerprints.”
That brought us to a technical discussion on metallurgy–not my field. Boiled down, Simpson said that a cast wheel is produced by pouring hot molten metal into a die. The process creates little air pockets, which can lead to “fatigue cracks that can reduce the strength and performance of the wheel.”
The way to solve that is to create a heavier wheel in which cracks take longer to form. That’s why cast aluminum wheels can weigh as much as 20 pounds more than a forged aluminum wheel. (Steel wheels, by the way, can weigh as much as 30 pounds more than a forged aluminum wheel.) The extra weight, however, can compromise handling. In this case, heavier is not better.
The rolling process that creates billet wheels help eliminate the porosity problem, but the process requires the manufacturer to build a two-piece wheel–a machined billet center welded or bolted to an outer rim. The weakness here is the strength of the weld that holds the two sections together.
Forged wheels, on the other hand, have no air pockets. Solid aluminum is heated, compressed, and formed into the shape of a wheel–a process that eliminates the pores that can lead to cracks. One-piece forging also aligns the grain flow of the metal, which significantly improves strength and durability. All of this means that the wheel is less likely to fail in tough offroad situations. The wheel may bend, but it won’t break.
And steel? The problem with steel wheels is that two separate welding operations are required: one to form the rolled rim, another to attach the center disc. Welds concentrate stress; and where stress is concentrated, failure gets an opportunity to do its worst.
Going to Extremes: I next asked Simpson to give me an example of how tough forged wheels really were.
“Easy,” she said. “The Ford Rough Rider offroad racing team has been on Alcoa forged wheels for the past four years. They’ve had more than 30,000 miles of desert racing without a single wheel failure. In the past, it’s been common to change a wheel three or four times in one event.”
“What has desert racing got to do with hunting and fishing?” I asked.
“Actually, a great deal. Offroad racing teaches us what can go wrong in extreme situations, which gives us the opportunity to make a good lightweight product for guys who hunt and fish in tough terrain.”
Again with the weight. “Most people don’t think weight savings is important, but it is,” Simpson said. “Lighter wheels improve handling, especially when you’re offroad. The less weight you have bouncing up and down underneath that spring, the easier the vehicle is to control.
“And as long as we’re talking ride, keep in mind that forged wheels ride better with less vibration. The design helps eliminate brake shudder and excess tire wear.”
To put the matter totally to rest, I called the owner of a truck conversion center, who said,
“In all the years I’ve been installing forged wheels, not one has been returned because of breakage. I think a major reason is the one-piece design. Two-piece wheels, which are also known as fabricated wheels, regardless of construction, don’t seem to fare as well over the long run in 4×4 applications.”
As for my tobacco-squirting friend, he no doubt recalls the debate that raged among hunters and fishermen a generation ago when aluminum wheels first made large inroads in the aftermarket offroad wheel market. There were some quality issues, but those were put to bed a long time ago. In fact, many trucks come out of the factory with stock aluminum wheels.
So, the big question: Should you buy cast, billet, or forged wheels? Forged wheels are the best overall choice, but however you decide to go, buy the best wheels you can afford. Cheap wheels, like cheap tackle, won’t do the job.
Looking Good: Outdoorsmen want a rugged wheel, but they also want to improve the appearance of their 4×4. An advantage of the forged aluminum wheel is that its bright chromelike appearance requires little maintenance. There is no paint to chip or flake off, and the wheel won’t rust–definitely a problem with steel.
“Although many companies use a conventional clear coating to help protect the appearance of the wheel, Alcoa does not,” says Simpson. Why? “Because the coating can be damaged in certain applications, which degrades the overall look of the wheel. With our wheels, all you need to do to keep them looking good is a seasonal wash and polish.
“The wheels may not help you catch more fish,” Simpson said before signing off. “But they’ll look good. And they certainly will get you where you want to go–and get you home again.”
“The Four Horsemen:” Let’s say you’ve got your eye on a set of smart-looking aftermarket wheels. What’s next? You need to make sure the wheels will fit your vehicle. This is a bit complicated, but if you follow the guidelines below you should end up with wheels that do the job.
Four characteristics determine wheel fit. They are: 1) size (wheel diameter and rim width); 2) bolt circle; 3) load rating; and 4) offset. Let’s look at each in turn.
1) Size: Select a wheel size appropriate for the desired tire and load-carrying capacity. A given tire size can fit a range of rim widths; in other words, a P265/75R15 tire can be used on a 7- to 9.5-inch wide rim. The rim width will affect the appearance of the tire by changing the sidewall profile.
2) Bolt Circle: A wheel has a number of evenly spaced stud or bolt holes. The bolt circle is the diameter of an imaginary circle that runs through the bolt hole centers. You measure from the center of one bolt hole, across the center of the hub face, to a point that intersects the imaginary circle drawn through the bolt hole centers. This measurement is usually stated in inches or millimeters.
3) Load Rating: The maximum load rating of the tire, wheel, and axle must be compatible. A bigger wheel does not always mean a bigger load rating. For example, several Alcoa 16x7J wheels carry maximum load ratings of 2,600 pounds, yet other Alcoa wheels the same size are load rated to 3,040 pounds. The load rating on your new customized equipment should be at least as high as the original equipment wheel and tire.
4) Offset: Of the four fitment characteristics, this is by far the most complex. Offset is the distance from the wheel mounting surface (mounting pad) to the centerline of the rim. Zero offset means the rim centerline is in line with the mounting surface. Negative offset means the centerline is outboard of the mounting surface; positive offset means the centerline is inboard of the mounting surface. Changing offset too much from stock may accelerate tire wear, impede steering response, and hamper stability.
“It’s a good idea to match the original equipment wheel backspace when going to wider tires. This helps prevent fitment problems,” Simpson says. “Getting the right offset for your particular application is 90 percent of successful custom wheel fitment. Offset is crucial to avoid clearance problems with fenders, struts, anti-sway bars, brake calipers, and other suspension parts. Maintain the wheel offset as close to stock as possible, especially on the front wheels.”
Six Steps to Success: Simpson recommends a six-step procedure that any professional installer can do for you. Following this guide will ensure that the new wheels fit the tires, and the new wheel-tire combination fits the truck.
1) Place the truck on a lift rack and raise it off the floor. Remove one front wheel.
2) Clean the mounting surface on the hub with a wire brush and remove any retainer (spring) clips.
3) Hold the aftermarket wheel (no tire) on the hub and check for a flush mount. The mounting surface of the wheel must fit flush to the hub mounting surface. The back side of the wheel must not rest against any obstructions such as the brake caliper, suspension components, balance weights, or rivets.
4) Install three lug nuts and hand tighten. Rotate the wheel and fully turn the steering wheel in both directions to ensure complete clearance.
5) Repeat the above steps on the rear of the vehicle. (The one exception is that you won’t need to turn the steering wheel.)
6) As a final check, mount the tires to the new wheels and install all four on the truck. Lower the truck to the floor. This will put the vehicle in a “true” ride position because the weight of the truck will settle on the tires, causing them to spread closer to underbody components. Do another check.