Not for highway use. It’s a common disclaimer found printed on the sidewalls of many tires intended for the track. And that’s despite carrying a U.S. Department of Transportation approval for street use.
How is this possible? In short, these are full racing slicks at heart, with just enough street characteristics built back in to meet the DOT’s regs.
That makes them compliant for various motorsports programs, but don’t expect any favors from them if they encounter wet conditions or road hazards on the street. If you trailer your vehicle to the track, though, these tires are a one-way ticket to consistently fast lap times. Welcome to the sticky world of R-comps.
While most current tires in this category look, drive and wear in a similar fashion, how they got to this point is a fascinating story of rules dodges, special tires for special people, and eventual consensus on where lines should be drawn–based largely on what was policeable.
The basic premise that got us here: Street cars should race on street tires, not the special racing slicks found on purpose-built race cars. So, of course, tire manufacturers had to push the limit on what constituted a street tire.
As other tire makers responded–win on Sunday, sell on Monday, right?–performance escalated quickly. But there was a cost: street manners and longevity. These race tires weren’t for everyone, though, and in some cases, buyers had to be “on the list” or sign a waiver.
Rule makers tried to respond but found it difficult to restrict motivated manufacturers. In the end, they drew the line at “DOT approved,” a minimum tread pattern, and equal availability to all competitors.
Meet the Latest Crop
From left to right: Hoosier R7, Goodyear Eagle RS, Yokohama Advan A055. Photography Credit: Andy Hollis
Our motivation for this test was Yokohama’s announcement of a new offering in this category, the Advan A055. And while the company’s previous efforts followed its traditional street tire-based formula, the new release is a minimalist, no-holds-barred, DOT-approved race tire. Exciting stuff. Initial shipments have reached our shores in only seven sizes, but an expanded lineup is on the way.
We wanted to compare the new Advan to the Goodyear Eagle RS, a capable tire we used on our recently retired C5 Corvette track car project. Goodyear has a long history in this category, being one of the first responders to Yokohama back in the ’80s with its Eagle VR50S–available only to racers but in four different compounds.
Which brings us to the reigning champ, Hoosier. As a race tire manufacturer exclusively, Hoosier’s original entry into this realm was different than the others: a sticky, bias-ply race tire topped with a tread pattern. This Street T.D. was fast–like, really fast. An even stickier version, called the Autocrosser, followed.
Hoosier moved to a radial design with its A3S01 in 2000. Every few years, it has revised that formula. Today, Hoosier’s R-comp offerings are available in both road race and autocross compounds, with the names simply shortened to R7 and A7.
We narrowed the available sizes to one size–205/50R15–that would fit one of our test vehicles, this time our One Lap CRX. The car is still in its NASA TT4 configuration, so figure 200 average wheel horsepower.
Photography Credit: Andy Hollis
We mounted the tires on 15x9-inch front and 15x8-inch rear 6UL wheels by 949 Racing for this car’s usual staggered fitment. Each set was treated to a four-lap heat cycle and then allowed to cool for 24 hours before testing.
On test day at Texas’ Harris Hill Raceway, we fitted up an older, scrubbed set of Hoosiers for a couple of practice sessions and track cleanup. Once the track conditions were stabilized, we started the comparisons.
Yokohama Advan A055
- best lap: 1:22.6
- tread width: 7.6 in.
- weight: 18 lbs.
- $292
All our tires wore the same size designation, but the Yokohamas were the narrowest of the group–almost half an inch less tread width than the others. The Yokohamas would have been right at home on 8-inch-wide wheels, but for consistency we kept the 9-inch wheels up front.
Once on track, we were delighted at the first turn of the wheel: This tire wants to dance! It’s super responsive and eager to dive into an apex. In fact, it took a couple of laps to dial in our hand movements.
Full grip was available almost immediately, but we continued to find time through lap four. Recovery was a bit lazy when the tire was overdriven mid-corner, and it was a little less adept at combined loading than the Hoosier–but still quite good. Its smaller size likely contributed to this overloading.
Goodyear Eagle RS
- best lap: 1:23.5
- tread width: 8 in.
- weight: 18.5 lbs.
- $245
The Eagle RS is styled a lot like the Hoosier, with a fairly square profile and minimalist tread pattern. It also seems a bit bigger than its markings indicate.
Once on track, though, the similarities end. Mid-corner grip was down relative to the other two tires and, like the Yokohama, recovery from beyond the limit was slow. Further, the Goodyear did not like to multi-task, so trail braking was a challenge and full acceleration off the corner had to wait until the wheel was almost straight. That said, longitudinal grip was exceptional, providing excellent forward bite and straight-line braking.
The RS turned on almost immediately, with its quickest lap being the first. Thereafter, it was super consistent across the entire session.
Hoosier R7
- best lap: 1:21.7
- tread width: 8 in.
- weight: 17 lbs.
- $322
The Hoosier R7 is the standard by which all other R-comps are measured. Every aspect of this tire is designed for consistently high performance on the track.
Its compound takes a lap or two to fully activate, but then it stays that way lap after lap. The carcass is very light, which aids acceleration and braking due to reduced rotational mass.
The tire also runs wide relative to its marked dimensions, which can be an advantage when rules regulate tire size. Our 205mm tires were as wide as some brands’ 225s.
On track, the Hoosier delivered as promised. Maximum grip was available by lap two, and we nailed four laps all within a tenth. Turn-in response was predictable but a little numb. If the Yokohama is a scalpel, the Hoosier is a big, grippy hammer.
Combined loading was a standout, enabling strong trail braking and early corner exit power-up. Breakaway at the limit was very manageable, and recovery was quick.
Yokohama Advan A055 (retest)
For our final session, we headed back out on our Yokohamas. Had the track conditions and driving remained consistent?
Familiar now with the tire’s lively turn-in characteristics, we nailed our quickest lap on the second circuit–a tenth better than our first session’s fastest lap. Later analysis showed that we hadn’t harnessed the tire’s full potential, as there were another two-tenths to be had by combining the best bits of our fastest laps from the two sessions.
Track Results
For sure, Hoosier’s relentless development has delivered an excellent combination of drivability, performance, consistency and longevity. The R7 wears its crown well.
Yokohama’s new entry is promising. The steering response is incredible, and grip is immediate and plentiful. The downsides we noted were possibly due to its undersized nature relative to the other tires. Right now, this is the only 15-inch size in the lineup.
However, this might help those who are limited by NASA’s tire templates, which go by actual tire width and not marked sizing. And the Yokohama’s surgical precision makes it a great candidate for autocross.
The Goodyear is a conundrum. It’s quick and consistent, but not quite at the same level as the others. In particular, it struggled to handle the multi-tasking needs of our nose-heavy, front-drive car. By contrast, it worked well on our nicely balanced Corvette and has been successful on larger, rear-drive cars in SCCA competition.
Again there are choices, and again the tires keep getting faster.
Let Your Usage Be Your Guide
We’ve assembled this chart to be a quick reference to choose the proper tire for the proper venue. For GRM’s updated tire guide and past tire tests, visit grassrootsmotorsports.com/tireguide.
- Autocross: Choose A or AA for warmup and B or better for time trial pace.
- Time trials: Choose by time trial pace and wear.
- Lapping days: Choose by heat tolerance and wear.
- Street and track: Choose by heat tolerance, wear and wet performance.
