You want to care about tires, but tires will always be, let's just say, not the most thrilling topic in the world. And confusing. It's almost as if the tire makers want you out of the loop. If they didn't, sidewall nomenclature would be easier to decipher, treadwear ratings would make sense, and a tire that uses the word "super" in its name would almost always be better than one that doesn't. Despite all of that, tires are the biggest contributor to your car not handling like something that's navigated with oars, so paying attention to them suddenly seems like a good idea. Make that a great idea.
Race-compound—or R-comp—tires have yet to be strictly defined. We know that their racing-derived rubber amalgam allows for solid on-track performance but with the ability to be used legally on the street. We also also know that, in terms of grip versus drivability, R-comp tires are the winner. A competition-spec, D.O.T. (Department of Transportation)-approved homologation of rubber that was neither wholly designed for the street nor the track, R-comps are the tire makers' best compromise between what the dealer thinks you need and full-blown racing slicks. But what exactly constitutes an R-comp tire is open to interpretation.
In the 1950s, tire manufacturers began experimenting with racing slicks. Street slicks appeared nearly a decade later, which differentiated themselves from track-only tires by little more than a couple of grooves carved along their faces. BFGoodrich was the first to introduce a full-fledged, D.O.T.-approved, competition drag radial in the 1990s, and has since been followed by nearly every tire maker in existence worth its own rubber. Today, such D.O.T.-approved R-comp tires yield the perfect balance of modest daily driver capabilities combined with near-racing-slick grip.
Like the tires on grandpa's Cutlass, R-comp rubber also features a radial design but is manufactured with strengthened sidewalls and a magical blend of sticky rubber. Not unlike other tires, R-comps are made from rubber, silicone, carbon, silica and plastic. The ratio of any one of those ingredients—the tire's compound—determines how hard or how soft it will be, and directly affects its performance. For example, soft tires yield better compliance and more grip but wear quickly; hard tires result in better fuel economy and last longer but aren't nearly as compliant. As you'd expect, the Cutlass' compound is slightly different than any R-comp's.
Because of their soft nature, R-comp tires have the potential to provide more grip than any suspension modification you might make, but they aren't without fault. First, they aren't cheap. R-comps also wear quickly, which makes them even more cost prohibitive. The number of heat cycles they can withstand before hardening is limited, which makes their ability to be used daily and then on the track questionable after time. R-comp tires also bear little resemblance to anything else and, if we're being honest, yield better track performance than they do streetability. Lastly, most R-comp tires don't play well in extremely low temperatures or in the rain.
The major benefits of an R-comp tire are its increased handling capabilities and on-center feel, largely due to stiffer, reinforced sidewalls that reduce distortion and specialized compounds that provide consistent performance, especially when heated. Generally, their tread designs are also reinforced for increased stiffness and feature a wider center area for more complete contact with the pavement. Many R-comp tires can also be shaved for greater traction, resulting in slick-like characteristics but without sacrificing their circumferential grooves. And unlike the Cutlass' all-season balloons, R-comps won't overheat, scallop or chunk up when beaten on.
Now's a good time to look at UTQG (Uniform Tire Quality Grade) standards, the rating by which a tire's performance and potential longevity is measured. UTQG standards were developed to help people like us make sense of all of the technobabble tire makers hope we'll understand. The ratings establish baselines for traction, temperature capabilities and treadwear. A tire's treadwear reveals two things: how long it will potentially last and how soft it is.
Adding another layer of complexity, R-comp tires don't necessarily bear the R in their names, like early D.O.T.-certified R-comps such as BFGoodrich g-Force R1s or the famed Yokohama A008Rs did. Today, many tires that would otherwise be classified as R-comps are labeled simply as D.O.T-certified competition tires. Fortunately, treadwear can indicate a tire's compound type: generally speaking, R-comp tires can be identified by having treadwear ratings of 140 or less and by having little or no tread pattern.
Understanding all of that information on your sidewall, including its treadwear rating, will move you one step away from knowing absolutely nothing about tires to knowing something important. As it turns out, a tire's three-digit treadwear rating, which ranges from around 0 to 700, will tell you a whole lot. For example, R-comp tires with ratings of 100 UTQG or less are typically best suited for the track and light street driving. Tires with ratings between 100 - 200 UTQG still yield acceptable grip but will last much longer on the street. Higher UTQG ratings sacrifice serious performance for longevity. But don't let a tire's treadwear rating serve as your only indicator as to its performance capabilities. Although a tire with a treadwear of 50 UTQG unquestionably has more grip than a tire measuring in at 450 UTQG, one with a treadwear of 80 UTQG isn't necessarily stickier than one at 120 UTQG. Modern tire designs allow for stickier compounds without significantly sacrificing treadwear ratings.
Unfortunately, for anybody who wants an objective rating, treadwear testing is conducted and its ratings assigned by the manufacturers. And since manufacturers set their own treadwear ratings, a 100 UTQG treadwear from one manufacturer can be completely different than a 100 UTQG treadwear from another manufacturer. Still, though, treadwear is a decent indicator of what you can expect from a tire performance-wise.
R-comps aren't the only performance-oriented tires available on the market. Street performance, high-performance and ultra-high-performance tires are enough to confuse you even more—especially the ones that claim to yield exceptional grip, yet maintain good tread life or wet-weather performance, the reality of which is a harder, less-pliable structure. And racing slicks, of course, have no tread at all, which lend themselves well to the track since a larger contact patch is realized. But R-comp tires are about as close as you can get to slicks without sacrificing streetability. In fact, the development of slicks—and later, cheater slicks—culminated into R-comp tires—a blend that resembles a slick's performance with their softer, stickier mix, yet passes all the muster of anything else that must comply with federal tire regulations, meaning some semblance of stability is maintained, even in the rain. In the end, choosing whether or not to use an R-comp tire is a matter of experience. If you don't have enough, find somebody who does. Better yet, ask someone who doesn't think tires are boring.