Our core readership knows that this magazine is all about functionality and not a bunch of Bling Stuff, or BS. True, we dabble in BS a bit just so we don't ignore those readers who we need to bring into the fold, and now and then we even like a bit of flash ourselves. We can appreciate a perfectly detailed show ride just as much as a beater that's been rolled hard and put away wet. Either side of the coin (and along the edges) is fine with us as long as it's functional. For instance, a 12-inch lift on a 1/2-ton old-box Chevy is fine, but using lift blocks up front and deleting the front driveshaft is not. That's not safe, much less functional, and all the bass-boat glitter paint in the world with screaming demon murals on the tailgate won't make it safe either. And your giga-watt stereo screaming out "Freebird" at 150 decibels and 20-inch Bling-Bling wheels? Yeah, probably should have spent the cash on a driveshaft.
But hey, we love Lynyrd Skynyrd and truly stylin' accessories, and we certainly don't pretend to be the fashion police. However, on the trail, functionality rules, and that means being able to hear axles snap or tires slip on crumbly surfaces, which is why we keep our radios at a sociable level. Who wants to confuse the sound of a rod knock with a thumping rap tune? But as far as wheel diameters go, have you noticed we don't promote or run 18s, 20s, or 22s? It's again a simple reason: functionality. Let's say you have a real-world trail tire of 35 inches in diameter. With a 15-inch rim, the sidewall will average out at 10 inches of sidewall from ground to rim. This is the working part of the tire which flexes and conforms around obstacles, especially at low off-road pressure. Now let's take the same diameter tire in a 22-inch wheel. That equates to only 6 inches or so, nearly half the sidewall of the previous example. This means less flex, less conformability, less comfort, and less performance. In addition, you can't let as much pressure out of the tire to improve performance, as you have less sidewall to deal with. Sure, for street performance using a short sidewall means better handling as the tire can't deform or squirm. If you're playing Mario Andretti on twisty pavement you want the sidewall to be stiff and predictable. You'll also have to suffer the bone-jarring ride as the tire can't soak up the bumps as well, but instead transfers them right to your rear.
Of course, there's always more to the story, and one reason for this dissertation is the fact that, yes, there is a place for a 20-inch bling rim in our arena, and here's why. One of the more unfortunate trends we've seen from tire manufacturers and wheelmakers is the increase of OEM vehicles with factory wheel sizes in the 18-22 BS size. Some manufacturers tout the increased highway performance of the wheel-and-tire combo, while others cite the larger brakes as the reasoning. The simple truth is they're all just lemmings following a fad, with no end in site. That's right, functionality is trumped by bling. This means that many of the new tires we want to run now only come in these overly large rim sizes, and unless the overall diameter of the tire is increased, the performance benefits of the new tire is negated in our off-road world. So what's a guy to do? Does size matter? You bet it does, and here's why. Just like our previous example of the 35-inch tire on a 15-inch rim had a good sidewall section, imagine a 52-inch tire on the same 15-inch rim. That gives a sidewall of about 18 inches, or over a foot of rubber flopping about without much control at low air pressure which can decrease functionality. The answer of course, is a bigger rim to get the sidewall-to-rim ratio back in the ballpark. For instance, a 20 rim on a 42-inch-tall tire gives you a good sidewall size of 11 inches, just about right for a good working combo. Even with BS, size does matter.