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Whale Watching: Bent Out of Shape

Truck Wheels

G.R. Whale
May 30, 2012
Whatever happened to universal wheels and the idea of thinking things through? For a device with the sole purpose of attaching tire to truck, wheels have generated many issues for me lately.
Some friends recently went on a four-day adventure in pickups. It wasn't a trail ride in the hard-core Jeep sense, just dirt roads, soft stretches, occasional rocky bits, and the rare mudhole. Four-wheel drive was all they needed, with no lifts or lockers required.
Then flat tires happened. When a 2000s-vintage Super Duty got a cut tire, then chipped a wheel at the bead and lost air, the simple fix would be to use someone else's wheel, since they were all driving -- or one-ton single-rears with similarly sized rubber. But simple fixes don't apply when one truck has an 8-on-170mm bolt pattern and everyone else's are 8 on 6.5 inches. So they had to swap the bad tire off the good rim and put the good tire on, which is no easy chore with hand tools and portable air.
Photo 2/6   |   Three HD SRW pickups and not a shared bolt circle among them.
Apparently, standardization is a bad thing. Ford decided the Super Duty should run an 8-on-170mm pattern, though I can't imagine the extra 5mm in bolt-circle diameter was needed, since new trucks put more weight/power through a 6.5-inch circle. Reinforcing my suspicion, the F-150 downsized a 5-on-5.5 to the smaller 5-on-135mm despite getting heavier and more powerful. There are still plenty of those odd-duck 150-HD and 250-LD F-150s running around on seven-lug wheels.
For the 2011 redesign, GM bumped its HD wheels to 8-on-180mm. Tundras originally used the same 6-on-5.5 pattern GM did, but that changed to 5-on-150mm with the 2007 Tundra. At least the GM half-tons are still 6-on-5.5, the Ram 1500 5-on-5.5, and the Ram HD 8-on-6.5.
Photo 3/6   |   GM Silver Left SRW
When did truck bolt-circle sizing get so goofy? Are we looking at unique wheel sizes next, like Michelin's mid-1970s TRX with a conventional bolt-circle but 15.4-inch (390mm) rim diameter, or Michelin's 21st-century PAX run-flat system, which requires special wheels? If the run-flats add as much weight as a spare, why bother with them on any vehicle that has plenty of space for a spare?
I remember near-universal 5- or 6-on-5.5 for almost every half-ton and full-size SUV on the road, and 8-on-6.5 for the rest, the only concern being offset when GM introduced its all-new 1988 half-tons. In some cases, you'd find -- 20 threads on one weight class and 9/16-18 or 5/8-16 on another, but lug nuts change easier than wheels.
It's also become popular to take alloy wheels and fit them with chrome-crusted plastic covers -- "chromed alloy wheels" is an inaccurate phrase. These fall off as much as other wheel covers -- I lost one on a paved highway expansion joint--and all the junk stuck behind them scuffs the wheels when you pull them off. Just polish or chrome the wheel.
Photo 4/6   |   Ram Silver Frt
Wheel design is such a driving force that some manufacturers toss function for form. I've seen steel and alloy wheels that have pockets in or behind the spokes and a recess around the periphery, outside, or inside of the spokes. These recesses trap sand, mud, snow, and ice around the edge, adding weight to rotating mass (which is often unbalanced), and corrode faster than a dry wheel, and the full-face steel ones occasionally preclude use of hammer-on weights. Perhaps the engineering offices in Michigan were overruled by bean counters in New York or stylists in California.
Then we have the experience of an acquaintance of mine. With solid axles, it's easy to lift a SRW F-350, and he wanted a sizable lift even though he pulled a fifth wheel. He figured he could get cool wheels with 38s under the truck and 35s under the trailer, with proper offsets and weight capacity (tires and wheels), and merely lift the trailer.
Photo 5/6   |   GM Red Right SRW
So a the truck got a suspension lift of about 8 inches. I reminded him that, without lower bump stops, there was no additional tire clearance -- the tire could still travel the same distance into the fender. He had an answer for that: "I don't drive that hard, and it doesn't flex." Maybe not when it's empty, but with 1.5 tons of hitch weight, it might. He lowered the bump stops, backed up to his trailer, and broke out the measuring tape.
By his calculations, a spring-over swap with some re-arched leaf packs, combined with 35-inch tires, would allow 5 inches of bed-to-trailer clearance. A stiff crosswind probably moves the trailer more than that, but I knew he'd have an answer for that, too.
Photo 6/6   |   Ford Burg Tan Left Srw
What this rocket scientist didn't measure was how tall the leading half of his sky-high fifth wheel was now, with all the tire and suspension lift under it. It was tall enough that the first bridge ripped most of the accessories -- A/C, vents, antennae -- right off, and his trailer was then more "custom" than he hoped.
All because the original wheels were boring.



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