Wheel Tech: The Wheels on the Bus Go Round and Round

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There are several basic specifications that should be considered when selecting wheels for your vehicle. The ones that leap out the most will be mentioned by your lift or vehicle manufacturer and were briefly discussed in “Understanding Wheel Dimensions.”

Though not the focus of this article, one other key wheel dimension that should be checked is the center bore. Most distributers will ship a wheel with the proper center bore based on the make and model year you provide in the ordering process, but you should still be aware of it.

WheelsWhy should I be aware of it? That’s a great question. The lugs that hold the wheel tight to the mounting plate are not designed to carry the weight of the vehicle (for the most part). They are there to interpret rotational force to the wheel, be it acceleration or deceleration, and keep the wheel snugged to the mounting plate. The lion’s share of vertical force (from hitting pot holes and holding up the vehicle) is actually transferred to the wheel center bore when properly fitted to the wheel hub. If a wheel is mounted with an oversized center bore, hub rings will be needed to bridge the gap in diameters between the hub and center bore. Certain wheel spacers could also be used but that is another discussion entirely.

Now for the wheel controversy. (Ed: Bonus points for the pun.) Which is better, steel or alloy wheels? Every Wrangler forum out there has a seemingly endless amount of threads on this subject. Perhaps the only topic with more debate would be the same question concerning manual versus automatic transmissions. Instead of writing a novel, the following is a summary of the main arguments out there.

Steel wheels are generally cheaper, they will be significantly heavier, and most threads agree that they are easier to repair in expeditious environments. I avoided mentioning strength because, as you will come to realize, that characteristic becomes a relative variable. Alloy wheels will be lighter, more expensive to drastically varying degrees, have little chance of repair, and offer a wide range of design features.

Most threads will simply argue that alloys are stronger and steel users will retort they have never gone wrong with their cheaper steelies. It’s a complicated argument, however, because alloy wheel strength has a lot of variant. Are they cast or forged and what alloy is being used?

Casting versus forging is the easiest to explain. A cast alloy wheel is heated to melting point, poured into a mold, and cooled. Forged wheels start as alloy stock, heated to just below the melting point, and pressed into shape under extreme pressures that actually cause changes in the metal’s crystalline alignment. It makes the alloy much stronger so less material has to be used and the wheel will be significantly lighter than even its cast counterpart.

Alloy composition is a science in itself. Years of research and volumes of material detail different alloys, very specific properties, and what each variant is best used for. To keep things simple, in most  wheel applications the two main materials involved are aluminum and nickel. The more nickel added to the alloy the stronger and heavier the wheel but, if it does bend, there is a higher probability of fracture.

After looking at all of my options, I finally chose a plain Jane alloy wheel. The Mickey Thompsons I had in the past were excellent wheels and never failed me. Cleaning them was a bear, (too much design relief for mud to hide in,) and the lug channels were too restrictive (a little grit and even a slim line socket wouldn’t fit). I got the simple and classic look of a steel wheel plus an affordable level of strength for my budget; I improved the ease of cleaning and wheel removal while decreasing my unsprung and rotational mass.

Your solution may differ significantly. If you barely ever go off road and really like that cool design, go with the top dollar forged wheel. If short term budget is your driving factor, steel may be best. Gas mileage an issue? Go alloy for sure. Beating the crap out of your trailered Jeep? Tough one. Steel is cheap to replace but a super strong alloy could do the trick too; experience will dictate. Obviously, for most of us, the decision will be a compromise for the best overall solution. Good luck and have fun picking the best wheel for your rig!

 

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