Race/street tire review
In the June edition of Road Racing World magazine (magazine website) - the review is NOT online.
Road Racing World Tire Test – July Issue 2005
Tires are round and black and made out of rubber—and they are the single most important factor determining whether a rider visits winner's circle or the hospital, between carving a graceful, knee-dragging arc through a corner or becoming a ragdoll launched into orbit, between having a fun track day or figuring out how to explain the pile of twisted aluminum and broken plastic in the back of the truck to a significant other. And with the goal of saving riders a lot of wasted time, money and possibly pain, we now present the latest, greatest blind tire comparison test. This time we tested tires in two groups: DOT-labeled racing tires, and DOT-labeled tires sold for street and recreational track day use.
In November of 1999 Roadrac-ing World conducted the first scientific, blind tire comparison test in the history of motorcycle journalism. What set that test apart from the evaluations done by other magazines wasn't the fact that we kept the test rider from knowing what tire he was riding on, (which we did). It was the fact that we measured each tire involved in the test and made adjustments to our test bike (a well-developed, Championship-winning machine) to compensate for the difference in actual installed size between the baseline tires and the test tires.
The point of all that extra work was to ensure that our test bike's geometry remained constant, allowing the rider to test the only thing different about the bike—the tires. It is sad that there are various motorcycle magazines around the world still comparing tires (and motorcycles) without measuring or compensating for differences in installed tire sizes.
For our previous test, we used the G.M.D. Computrack machine at Jim Rashid's 4&6 Racing to measure each set of tires mounted on wheels and installed on our test bike. Then Kent Soignier put those numbers into the G.M.D. Computrack system's "What If..." program to tell us how to adjust the bike back to its original geometry.
Since that time we have adopted a simpler way of measuring the difference in the size of any two tires. For this test, we mounted each tire on a wheel, positioned the wheel perfectly vertical on a test bench (using drafting straight edges for reference) and measured the height from a designated point near the wheel's axle to the table's surface. This essentially gave us the difference in radius of each tire. The difference in that measurement for two tires told us what changes we needed to make.
The largest difference we found was, as usual, between the Dunlop and Michelin race tires—we found that the Dunlops have a 12mm larger rear radius and a 3mm larger front radius. The geometry change caused by switching from Michelin tires to Dunlop tires would be, in this case, the equivalent of raising the rear ride height of the motorcycle by 9mm. That type of change can have a dramatic effect on the handling of a motorcycle—often inducing a tendency to tuck the front end—while also affecting final drive gearing and swingarm-to-rear-tire clearance.
The high-performance street/track day tires covered a range of 2.5mm among all the fronts and 8.5mm among all the rears.
We highly recommend that anyone changing tire brand and/or size measure the old and new tires and make any needed adjustments, to avoid screwing up the set-up geometry. Another thing to consider is that each tire has unique damping characteristics, and may require different suspension spring rates and valving for optimum performance. For simple logistical reasons, we couldn't completely sort out the suspension to suit each tire, instead staying with a proven baseline suspension set-up on our test bike.
We weighed each dismounted test tire and found a large difference between the weights. For the weights, see the chart on page 55, but in short, two individual tires (Michelin Power Race and Dun-lop Sportmax GP) varied in weight by as much as three pounds. And remember, that's unsprung, rotating mass.
We conducted this test at the same track we used five years ago, Oak Hill Raceway, near Henderson, Texas. Oak Hill Raceway is a privately-owned road course located in the middle of pasture land in eastern Texas. Not many people have heard of the track because it only hosts CMRA motorcycle club road races and shifter kart races, but don't let that fool you. Freddie Spencer, Kevin Schwantz, Colin Edwards, all three of the Hayden brothers and Ben Spies— among others— spent their developing years racing on this twisty, undulating 1.8-mile, officially eight-turn (but in reality more like 14-turn) road course.
Texans like to say, "If you can go fast at Oak Hill, you can go fast anywhere," because Oak Hill throws a little bit of everything at a rider except a place to rest. Corners vary from wide, smooth, 95-mph turn one, to the patched, bumpy, 40-mph "School House" hairpin. Hardly any part of the course is flat, and many of the corner entrances are blind. And Oak Hill has some of the highest-grip, most tire-torturing asphalt seen in modern club racing. All of which makes Oak Hill a very good tire test track.
Since our last visit, Oak Hill has undergone extensive improvements. It has been re-paved from the entrance of turn eight through the exit of turn one, and several other areas of the track have been patched with a grippy concoction known as Rhyno Hyde. However, there are still many bumps—and even ruts—in several areas of the track.
Among the advantages of using Oak Hill are mild weather (between 65-75° F during our test), the ability to see almost the entire track from the main grandstands and the fact that we have many friends in the area who were willing to come out and lend us a hand, Including AMA Pro racer John Haner, current Oak Hill track record holder Michael Sanchez and his brother Gabe Sanchez, and Marcus McBain of Racing Performance Services (RPS, 713-304-5509) with crewmen John Ross and Leonard Gremillion.
For our testers, we used Racing Editor Chris Ulrich and Assistant Editor Steve Atlas. Ulrich has won two AMA National road races, an overall WERA National Endurance Championship, a Suzuki Cup Championship and more importantly, he has raced on Pirelli, Dunlop, Michelin and Bridge-stone tires mounted on everything from YSRSOs to lOOOcc Superbikes since he started racing at age 13.Atlas has won CCS National Championships as well as several class Championships with CRA (his home club), has also raced on several different brands of tires and has sampled many other brands of tires during his time on staff here at Roadrac-ing World,
For the test, Ulrich rode his well-developed, race-winning 2003 Suzuki GSX-R1000 Super-stock bike, which was originally set up on Pirelli Super Corsa slicks and carried exactly two gallons of fuel during each test run. Atlas rode a lightly-modified 636cc 2005 Kawasaki ZX-6R streetbike, which he set up using its original Bridgestone BT014 tires as a baseline. Atlas rode with a full fuel load for each test stint.
We chose the 636cc Kawasaki for this test in hopes of providing relevant information for riders of both 600cc and 750cc machines. In addition to stripping a few street parts off the Ninja to ease rear wheel changes, we fit it with Linde-mann Enterprises-modified forks and an Elka shock, both sprung for Atlas' relatively light, 140-pound weight. A modified/after-market suspension set-up is far from unusual for a track day rider and it ensured that our set-up would stay consistent throughout the marathon test day, eliminating any chance that the stock shock would overheat and lose damping capabilities.
McBain and his RPS crew, working in conjunction with Road-racing World project Crew Chief Ed Sorbo, helped Atlas set-up his Kawasaki while he learned Oak Hill on the first day of the test. Sorbo also oversaw all of the bike preparation, wheel and geometry changeovers and countless other tasks that made the test run more smoothly than It did during our previous effort.
Both bikes were fitted with data acquisition systems supplied by AiM Sports (800-718-9090).
A MXL Pista plug-n-play system plugged right into Ulrich's Suzuki and supplied lap times, engine speed, road speed, throttle position and gear position, but its track mapping feature failed to produce anything remotely resembling Oak Hill. The MychronS Gold system on Atlas' Kawasaki was a prototype system for the 2004 ZX-6RR. Because neither a 2005 system nor a 2004 bike were available, we hoped the 2004 system would work with the 2005 bike. It did mount onto and plug into the 2005 ZX-6R and collected lap times, engine speed and mapped the track, but it failed to produce road speed, which prevented us from comparing mid-corner and straightaway speeds between tires.
To collect our test samples, we contacted several different tire manufacturers and asked for their "best DOT-labeled, production road race tire in sizes 120/70-17 and 190/50-17, in a compound in the middle of their available range" and their "best high-performance street/ track day tires in 120/70-17 and 180/55-17." Ulrich would test the race tires on his race-bike. Atlas would test the street tires on the modified streetbike. Bridgestone, Dunlop, Michelin and Pirelli accepted the DOT-labeled race tire challenge. Although Metzeler has a RaceTec DOT-labeled race tire in Europe (where it has done very well in some magazine tire shootouts), the German company does not plan to market the tire in the United States in 2005 and declined to send us test samples. Avon's U.S. importer also chose not to supply us with Avon AV49/50SP Pro Series Xtreme race tires.
We had several more takers for our high-performance street/track day tire test. Avon, Bridgestone, Continental, Dunlop, Maxxis, Metzeler, Michelin and Pirelli quickly sent samples, but Dresser Tire & Rubber Co., Inc., re-manufacturers of the Tomahawk race and street tires, did not return several telephone calls and e-mail inquiries from Roadmcing World.
Each test tire was stored in the same, cool, dry environment until being transported to the test track. Air pressures were set at each tire manufacturer's recommended setting for track use with one exception: Continental's spokesman recommended that we set the Continental tires at 36 psi front and 42 psi rear for the racetrack, which set off warning buzzers in all of our heads. Leaning on the vast amount of track experience among the Roadracing World staff and in the interest of Atlas' health and welfare, we chose to set the Continentals at a much lower, more conventional air pressure for the test.
During the test we used thermostat-controlled Chickenhawk-brand tire warmers to bring the race tires up to the manufac-
turer-recommended temperatures for the manufacturer-recommended duration before going on track. Most of the tire manufacturers had no recommendations for the usage of tire warmers in conjunction with their high-performance street/track day tires. With that in mind and in the interest of safety, we chose to bring all of the high-performance street/ track day tires up to 125° F, front and rear, before sending Atlas out on track. Knowing that the street tires are designed to work in a lower temperature range and that 125°F is hardly hotter than tires can get if left in direct sunlight on a hot summer day, we felt confident that this was a safe middle ground.
The riders were kept away from the work area where wheels were changed on the bikes, and tire warmers were kept on the tires until the rider was on the bike and ready to roll out onto the track When the rider returned to the paddock, tire warmers were re-installed before he was allowed to get off the bike. The riders did not know what brand tires they were on, although in one case, the rider made a pretty accurate guess based on tire feel.
As with our original tire test, we offer this disclaimer: Ideal air pressure settings, tire warmer temperature and duration, and tire rubber compounds may vary from track to track. When setting air pressures or using tire warmers or selecting which compound of rubber to use, riders should follow the recommendations of their local tire distributor or the tire manufacturer.
We have provided a chart showing the differences in actual tire size and the changes required to return our test bikes to their original set-ups, but this does not guarantee these numbers will work for you and your bike set-up. Whenever you change brands of tire or even switch to a different model of tire from the same manufacturer, you should measure the difference between your known tire and the new tire and make the appropriate adjustments, if needed.
Race Tire Test
Race Tire Brand One (Bridgestone)
After waiting a couple of hours for the track to fully dry following overnight rains, we sent Ulrich out on Race Tire Brand One, which had been heated to 80°C front and rear, on a track that measured 91.4°F with an ambient temperature of 70°F. Ulrich immediately started turning quick lap times and ended up with a best of 1 :26.997 on his fifth of six flying laps. This turned out to be the quickest lap time of the test.
"The rear had really good grip from the get-go, straight out of the box," said Ulrich. "It was like, 'Wow! I'm driving out of the corner and I'm not sideways.' Through turn six, I was totally sideways out of there before. Now it's way bitchin'!
"Over the bumps, it wasn't very good. It seems like I could feel more of the bumps on the track, but it still had really good grip around the entire thing.
"The biggest problem I had was chatter — from both ends, but mainly the front — through turn one and some of the faster stuff. It chattered for the first four or five laps. Once it rubbed off, the last couple of laps were better.
"The front felt good and stuck. Through turn two, the grip was there. I was pushing harder and harder each lap going In on the brakes, on the front, on the trail braking. It's amazing. It's so much better than the control tire, and the control tire was a slick. I could just throw the thing in the corner, real precise, and it totally hits the line and doesn't run wide."
The Aim MXL Pista data acquisition system saw the same things that Ulrich mentioned, except for the chatter. Ulrich's throttle position consistently went to maximum quicker and more often than with any other tire. His drives/acceleration out of corners were consistently better, resulting in more speed between most corners. Ulrich was also able to carry that extra speed into the corners, resulting in most of the highest apex speeds of the test.
The key to getting a good lap time at Oak Hill is putting
the section from turn eight to turn two together well. On his fast lap with Race Tire Brand One, Ulrich was able to carry decent apex speed at turn eight, build the most speed before entering turn one (125.6 mph), carry the most speed through turn one (minimum apex speed 96.9 mph) and build the most speed down the next straight away (128.5 mph) before carrying the most speed into turn two (44.1 mph).
Ulrich said Race Tire Brand One reached its high level of performance immediately and did not show any signs of fading during his six, hard laps. He also added that it took much less effort to go fast on Race Tire Brand One than it did on his control tires.
Ranking 0 to 10, with 10 being the best, Ulrich gave Race Tire Brand One many eights, with a nine for trail braking. However, he rated Race Tire Brand One's Bump Absorption at a five, the lowest score it received.
Race Tire Brand Two (Pirelli)
After a short break for the wheels to be changed and the geometry to be adjusted, Ulrich headed back out onto the 96.0°F track (ambient temperature 72°F) with Race Tire Brand Two, which had been heated to 80°C for the recommended amount of time. Again, Ulrich looked comfortable and immediately started turning quick lap times, but his lap times dropped off after the second flying lap, about the same time the rear tire could be seen squirming under acceleration out of turn five.
"The first two laps were pretty good," said Ulrich, after turning a 1:27.027, the second-fastest lap of the test, on lap two of six. "Then every other lap after that, I couldn't get on the gas as early, and I couldn't trail brake as hard. I lost the front two or three laps in a row in that back corner, turn six. Coming down the hill (to turn five), it was sideways coming down the hill where that other tire was driving. Did you see me get kicked out of the seat there, coming out of five? That was pretty much the deal. So I decided to back off."
Ulrich said the tires were good to go right out of the gate but got progressively worse after the second lap. 'They were OK on the brakes," said Ulrich. "I could throw the thing on its side, but they didn't have the side grip that those other tires did. It turns in pretty well, but once you get to full lean it just doesn't handle that good. On the first tire, when I would come through one and hit that bump (at the exit), it was actually pretty good. This one, I hit the bump and it upset the bike a little bit. I don't know how fast I went, but it didn't feel as good."
The data acquisition system backed up Ulrich's feedback that he did in fact have to back out of the throttle occasionally while hitting the bump at the exit of turn one, but he still reached 128 mph before turn two after starting at a lower (90.1 mph) turn one apex speed than Race Tire Brand One. The speed traces of Ulrich's fastest lap on Race Tire Brand Two also show wheel spin coming out of turn three on his fastest lap, resulting in 6.0 mph less speed into turn four than with Race Tire Brand One, but a better drive and mph (125.1) down the hill to turn five than with Race Tire Brand One. Overall, the data acquisition system showed Race Tire Brand Two to have lower mid-corner speeds but some better drives in the early laps when compared to Race Tire Brand One.
Ulrich gave Race Tire Brand Two all sixes and sevens on his score sheet. The tire earned the lower marks in Trail Braking, Mid-corner Grip (front and rear) and Predictability/Consistency.
Race Tire Brand Three (Michelin)
With clouds building overhead, the track cooled to 87.8°F and the ambient temperature dropped to 70°F for the run on the Race Tire Brand Three samples, which were heated to 70°C, front, and 90°C, rear, for the recommended amount of time.
"That was a good tire!" exclaimed Ulrich, after turning a third-fastest 1:28.008 on his fifth of six hard laps. "It felt like a Michelin, flat out. That thing slid like a Michelin. Michelins don't do a nice, long slide. They do a Whoo! Whoo! Whoo! But it's not like you're sitting there spinning the thing out of control. You're driving forward the entire time, and it's pretty predictable when it's doing it.
"It had a lot of grip on the left side when it was hot, but the right side never really came in. I could see the left side of that particular tire going away in three more laps because it was really starting to buck, but it wasn't really uncontrollable bucking. It was going forward. It wasn't like the control tire, which would buck and kick me out of the seat.
"I could trail the brakes in on that tire the best. It had a lot of side grip. The first two laps,
however, it was hard to turn the bike in, which is another Michelin trait. Once they get warmed up, it's a good tire.
'The biggest tiling that's going to shoot that particular tire down Is the right side. I couldn't get down the hill, or over bumps. It didn't absorb bumps for sh-t, front or rear. It would hit a bump and slide, but it wouldn't buck me out of the seat. Typical again of a Michelin."
The Aim MXL Pista system showed that Tire Brand Three had equal—if not better—apex speeds than Race Tire Brand One. And in spite of Ulrich's feedback, on his fastest lap on Race Tire Brand Three, he got better drives (indicated by higher speeds when arriving at the next corners) out of right-hand turns four and five than on Race Tire Brand One. However, on that fastest lap, the data showed that Ulrich was unable to get the throttle wide open exiting turns seven (left) and eight (right), while he could with other tires.
Ulrich rated Race Tire Brand Three's Turn-in Grip at nine, while giving every other categoiy a seven or an eight. However, Ulrich gave Tire Brand Three a five for Bump Absorption.
Race Tire Brand Four (Dunlop)
The air measured 72°F and the track surface was 86.3°F for Race Tire Brand Four, the samples of which were heated to 170°F for 45 minutes, as recommended. Ulrich turned his fastest lap on Race Tire Brand Four, a 1:28.415, on lap two of six, but his lap times bounced around quite a bit from that point on, turninga 1:28.6 one lap, a 1:29.3 the next and a 1:28.5 the lap after.
"Right out of the gate, I went into the first turn and the thing was like Whoa! I went into a slide right out off the gate, both ends. Tip the thing in and whoosh!" said Ulrich. "It doesn't absorb bumps for sh-t. It had a super stiff carcass, it
seemed like. You hit the bump and it's like bam! A big hit, then the thing slides. I tried to get the gas on and I had no grip, no drive grip, no nothing."
Ulrich elaborated on the lack of drive grip, saying, "You had to wait so long, until you had the thing fully stood up. And it didn't give me good feedback. Like, 'OK, I'm going to slide now...maybe...no.' No feeling at all.
"You could get on the brakes and get it in there. It would turn in, no problem. But you best not be on the brakes at the apex. You better have your braking done and then be turning, or be very low on your trail braking. With Race Tire Brand Three, I could whooom! Right to the apex, keep big brake on, turn it and fire it out. With this thing, it was like Whoa! Whoa! Whoa! Whew! I made it! It seemed like the rear wanted to back itself around going into corners. Once you did the initial turn, it stuck until you opened the throttle."
The data acquisition system showed that Ulrich was unable to give Race Tire Brand Four as much throttle coming out of left-hand turn three and right-hand turn four as other tires. Race Tire Brand Four's speed at the apex of the slower corners was nearly up to par, but never built the same mph on the short straights or carried the same speeds through most corners as its competitors.
Ulrich said Race Tire Brand Four was slow to come up to temperature on the track and stayed at a low level of performance through his six laps, resulting in him giving Race Tire Brand Four the lowest marks of the four competitors.
Race Tire Test Results
When the subjective scores were tabulated, Race Tire Brand One had a small lead over Race Tire Brand Three, but when the objective scores from Fastest Lap Time, Fastest Average Lap Time and Smallest Spread of Fastest-to-slowest Lap Time (Race Tire Brand Three had the smallest spread, 1.168 seconds, showing consistency) were factored in, Race Tire Brand One and Race Tire Brand Three were tied. Ulrich's preference served as a tie-breaker, giving the DOT-labeled race tire shootout crown to Race Tire Brand Three - the Michelin Power Race.
"The (Michelin) front tire was the best," said Ulrich, before knowing the true identity of the tires. "The front tire was so good. I could go in, throw it in on the brakes. The rear wasn't that great. It was good, but it wasn't like Race Tire Brand One's rear. The only problem I had with (the Michelins) was the right side wasn't getting hot enough. Maybe they need a hotter day or whatever. But flat out, I'm a front tire guy, and that front tire was really good. That's what won it."
Second place went to Race Tire Brand One—the Bridge-stone Battlax BT002, which not only led the subjective scoring but also recorded the fastest overall lap time, the lowest average lap time (showing consistently high grip) and the second-best spread of lap times. "The rear was really good. It had really good side grip, and it drove the thing out of the corner really well. It had good feeling, too. It didn't pump or squirm like (the Michelins), which would still drive forward. (The Bridge-stones) would just drive forward. The front (Bridgestone) just wasn't as good. It had too much chatter at the beginning. It was a really good front tire, but (the Michelin's) front tire was golden."
Third place went to Race Tire Brand Two—Pirelli's Super Corsa Pro. "They were pretty squishy. I don't really mind that. They were really good over the bumps. It just didn't seem that they had the outright grip that (the Bridge-stones) and (the Michelins) had. Not the outright side grip. The drive grip was OK. The front tire could have been better, too," said Ulrich, in spite of turning a faster lap time on the Pirellis than on the winning Michelins.
Race Tire Brand Four—the Dunlop Sportmax GP finished fourth—last. "Those things were scary, flat out. Those guys need to go back and figure something out," said Ulrich, bluntly.
Manufacturer, model of tire, compound, size, manufacture date code, country of manufacture:
Bridgestone, Battlax BT002F Racing, Type 3,120/70-ZR17,0904, Japan
Bridgestone, Battlax BT002R Racing, Type 3,190/50-ZR17, 0704, Japan
Dunlop, Sportmax GP, 758,120/70-ZR17,4904, England
Dunlop, Sportmax GP, 313,190/60-ZR17, 0705, England
Michelin, Power Race, Medium, 120/70-ZR17, 3904, France
Michelin, Power Race, Medium, 190/50-ZR17, 3604, France
Pirelli, Super Corsa Pro, SC2,120/70-ZR17,4704, Germany
Pirelli, Super Corsa Pro, SC2,190/55-ZR17, 4004, Germany
1. Michelin Power Race 20 Ibs. 14 oz.
2. Pirelli Super Corsa Pro 22 Ibs. 1 oz.
3. Bridgestone Battlax BT002 23 Ibs. 10 oz.
4. Dunlop Sportmax GP 24 Ibs. 14 oz.
Tire Test Air Pressures (Cold):
Bridgestone BT002F/R, 31 psi front, 30 psi rear
Dunlop Sportmax GP, 30 psi front, 27 psi rear
Pirelli Super Corsa Pro, 30 psi front, 28 psi rear
Michelin Power Race, 31 psi front, 22 psi rear
* All cold tire air pressures used were recommended by representatives from each respective manufacturer, except for the Continentals. Continental Tire North America Sales Manager Motorcycle Tires Greg Reich recommended we use 36 psi front and 42 psi rear, writing in an e-mail that the Conti Force Max rear was designed to run at a higher psi but gave us the option of using a lower air pressure. Leaning on thepast and vast experience of our staff and in the interests of safety, we decided to go with more conventional air pressure settings.
Changes Necessary To Restore Baseline Geometry Due To Differences Between The Sizes Of The Baseline Tires And The Sizes Of The Test Tires:
Race Tires (baseline tires Pirelli Super Corsa slicks):
Bridgestone Battlax BT002F/R, lower front 1 mm, no change to the rear
Dunlop Sportmax GP, lower front 6 mm, lower rear 2 mm
Michelin Power Race, raise front 1 mm, raise rear 6 mm
Pirelli Super Corsa Pro, no change to front, lower rear 1 mm
Tire Company Contact Info:
Avon Tyres North America, 407 Howeil Way,
Edmonds, WA 98020, (800) 624-7470, www.avonmotorcyde.com
Bridgestone/Firestone North American Tire, LLC,
535 Marriott Drive, Nashville, TN 37214, www.motorcycle-karttires.com
Continental Tire North America, Inc., 41 Strong St., Wellington, NJ 07057, (914) 471-8890, www.conti-online.com
Dunlop Tire Co., P.O. Box 1109,
Buffalo, NY 14240-1109, www.dunlopmotorcycle.com
Maxxis International USA, 545 Old Peachtree Rd., Suwanee, GA 30024, (800) 4AAAXXIS, www.maxxis.com
Metzeler Motorcycle Tires, 100 Pireili Drive, Rome, GA 30161-3538, www.us.metzelermoto.com
Michelin Consumer Relations Department, P.O. Box 19001, Greenville, SC 29602-9001, (800) 847-3435, www.us.michelin.com
Pireili Tire N.A., LLC, 100 Pireili Drive, Rome, Georgia 30161-7000 (800) PIRELLI (747-3554), www.us.pirellimoto.com