Choosing the perfect tire for motorsports is simple, proper? Merely select the widest fitment together with the stickiest rubber allowed by the principles. No less than, that’s what the web says.
If solely that had been the case. As we lately skilled, generally you have to make some seemingly unconventional comparisons to seek out the most suitable choice–which led us to this explicit take a look at.
Spherical 1
Take a look at day dawned heat and sunny, with temps starting from the mid 80s to mid 90s whereas we labored. Given the warmth, we opted to run solely 4 laps on every tire to cut back turnaround time. Swapping solely the fronts additional helped decrease warmth soak. We did just a few laps on some outdated scrubs to scrub up the observe and knock off the rust.
Nankang Sportnex CR-S 245/40R15
- Wheel: König Dekagram 15×10 ET25 with 6mm spacer (35 lbs. complete)
- Quickest lap: 1:24.20
This combo was fairly good, with just some delicate understeer in lengthy sweepers. It tracked straight and true over the bumps on the again straight. Oddly, it stored getting sooner on every lap, with the ultimate go being the quickest. Wanting on the knowledge later, it was clear that the few warmup laps we’d completed on the scrubs weren’t sufficient–the observe was nonetheless evolving. In our haste to get going earlier than the solar soaked the observe, we’d compromised the primary session a bit. Sigh.
Nankang Sportnex CR-S 275/35R15
- Wheel: König Dekagram 15×11 ET20 with 20mm spacer (38 lbs. complete)
- Quickest Lap: 1:22.88
This setup was very fast. The additional width allowed for deeper braking on entry and earlier throttle software on exit. The dealing with was additionally higher balanced. It did tramline excessively on the again straight, although, following each undulation of the bumpy floor.
Vitour Tempesta P1 285/30R17
- Wheel: König Hypergram 17×10 ET43 with 25mm spacer (46 lbs. complete)
- Quickest lap: 1:23.17
Whereas the 275mm Nankangs had given us three strong laps, the Vitour fell off a bit by the center of the second lap. It then stabilized for the following two. Single-lap tempo was not fairly on par with the 275mm-wide Nankangs, although. Was this because of the narrower wheel width of 10 inches versus 11?
Information evaluation confirmed the tempo delta to be nearly solely underneath acceleration. The perpetrator? Rotating that considerably heavier wheel-and-tire bundle with much less mechanical benefit resulting from taller OD. It was positively faster underneath mixed loading, gaining again a few of the deficit underneath path braking.
Nankang Sportnex CR-S 245/40R15 retest
Bracketing our day with the 245mm Nankangs, we discovered a bit extra velocity this time round and earlier within the session. This felt extra consultant of the tire’s true tempo. It additionally mirrored the lap time delta between it and the 275mm Nankang that we’d seen in our earlier take a look at on the Triple Risk ND Miata.
Spherical 2
Pondering the outcomes whereas we waited for our BFGs to point out up, two issues bugged us: the flawed bracket resulting from inadequate warmup time and the tramlining of the 275mm Nankang. Was that feeling because of the excessive observe width improve over the narrower 245? Massive spacers can usually make a giant change in dealing with. Just one approach to discover out: one other take a look at.
This time we’d take an extended cleanup session after which use two pairs of 245s, one run as earlier than and the opposite with the bigger spacer mirroring the observe width of the 275 as finest we might. We’d additionally pay attention to any change in really feel with the massive spacer added.
These outcomes again up the primary take a look at nearly completely. Notably, the massive spacer made no discernible distinction in both tempo or really feel. Case closed: The 275mm-wide Nankang Sportnex CR-S on an 11-inch-wide wheel was merely imitating an oil drum rolling on its aspect.
We additionally took the chance to get a learn on relative efficiency of our new quickest setup versus what we had been operating, shaved 225mm-wide Yokohama Advan A052s on 9-inch-wide wheels. That consequence was simply shy of a full-second enchancment. Good!
Spherical 3
As soon as our BFGoodrich tires arrived and got a warmth cycle, we did yet one more spherical of testing to get one other knowledge level on the Rival S versus an equal-sized competitor. Seems it’s not fairly as fast because the Nankang Sportnex CR-S. We additionally tossed on the Yokohama Advan A052s once more for yet one more shot and obtained the identical outcomes as earlier than. Be aware that the entire wider setups had been faster than the narrower Yokohamas.
Conclusions
So, about that web tribal knowledge of operating the widest and stickiest: If we’d blindly adopted it and chosen the massive Vitour Tempesta P1s, we’d have missed out on our eventual winner, the 275/35R15 Nankang Sportnex CR-S on a 15×11-inch wheel. Seems the load and gearing impact overcame any potential grip benefit.
Wouldn’t it have been totally different had the Vitour been mounted on 11-inch-wide wheels? Perhaps. However in the intervening time, no 17×11-inch wheels exist in a 4×100 bolt sample aside from costly customized ones.
However Vitour claims to have its personal 275/35R15 measurement coming quickly. In the meantime, we’ll be operating 275 Nankangs in competitors–and because the out there choices change, we’ll be again to do extra testing.
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