Tire / Rim Protectors(Lea en español)
While curbs and debris on the road have never been considered a tire's friend, many of today's tires resist accidental damage by featuring thicker rubber molded at key locations on their sidewalls. This helps reduce damage to the tires and/or wheels when drivers accidentally rub them against curbs while parking or turning sharply out of a driveway.
However, most standard tires don't feature rim protectors of any kind (Photo #1) because they are frequently mounted on steel wheels. While this may initially appear to be an oversight, it is really done to accommodate the reality that most steel wheels use hubcaps to provide a more desirable appearance. The absence of a rim protector allows more flexibility in hubcap styling and how hubcaps are designed and attach to the wheel.
The tires that feature tire/rim protectors use several different designs. Many of these tires feature a raised rib adjacent to the bead area on their lower sidewalls or have a deeply recessed bead area to partially envelop the wheel flange. Other tires feature raised ribs at the tire's maximum section width (the distance between a tire's sidewalls measured at the widest part of the tire).
Tires featuring the raised rib adjacent to the bead (Photo #2) or the deeply recessed bead area (Photo #3) are designed to help protect low-profile tires and expensive alloy wheels from accidental curb damage. While tires featuring the raised rib or molded recess design will often thwart the use of wheel covers, this typically isn't a problem since these tires are customarily used on vehicles equipped with alloy wheels.
In light truck off-road applications, the rim protectors will also help shield the tire and wheel bead area from debris, as well as resist damage inflicted by rocks, tree stumps and other off-road obstacles.
Tires featuring one or more raised rib(s) at their maximum section width (Photo #4) are often found on delivery vans and trailers. The raised rib's extra rubber thickness at the widest point of the tire resists damage to the sidewall and increases the amount of rubber that must be worn away before repeated curb scuffing cuts or exposes the tire's internal cords.
So whether their manufacturers call them "Maximum Flange Shields", "Rim Protectors" or "Scuff Guards", the purpose of all tire/rim protectors is basically the same. They are intended to sacrifice themselves in order to protect the tire's internal sidewall structure and the alloy wheels upon which they are mounted.