Dunlop has released the street going version of their 208 series tires. Following the nomenclature of the past, the new tire is called the D208 ZR and is claimed to be an improvement over the D207 ZR in handling, ride comfort, mileage, and grip in both wet and dry conditions.
The ZR is not just a GP (Dunlop’s race tire) with a harder compound. Hard compound race tires usually need a few laps to really come up to temperature, most street riding never even gets a tire warm. Street tire, therefore, have to stick well at cooler running temperatures and, of course, the compound also has to work, to some degree, in the rain.
This make building a good street tire even more complicated than race tires where operating temperatures and conditions are much more of a constant than on the street.
One compound trick than many of the top tire manufacturers are employing is mixing Silica (generally reserved for rain tires) into the street compound. Dunlop has used three different elements to provide balance between wet and dry conditions; A high grip styrene butadiene rubber polymer and ultra fine carbon for dry grip mixed with silica for wet grip and better wear characteristics.
The carcass has been improved from the D207 ZR with various techniques like Jointless Band technology and Carcass Tension Control System. These various obtuse phrases translate into a tire that is stiff enough to handle the loading from hard cornering but is 1.2 pounds lighter in the front tire and 1.7 pounds lighter in the rear. That sort of weight saving is impressive and a hell of a lot cheaper than magnesium wheels. The ZR also has a slightly more rounded profile than the GP tire but is a little more triangular than the D207 ZR.
The cosecant curve tread pattern is apparently not just a trendy tiger stripe but is to align the voids in the rubber with the loading on the tire at different lean angles during acceleration. It seems that most of the advantages in the tread design are for the rear tire solving the mystery as to why it was the trick setup to run some of the D207 GP front tires backwards. The tread pattern on the front tire was not as important as the direction of the carcass.
The tires are available in the following sizes:
I grabbed the 2002 R1 while Melissa jumped on the 748.
Being reasonable familiar with the track I concentrated on A. not back shifting the street shifting R1, B. Testing the feel of the tires while they were still cool and the track had not gotten really warm (asphalt in southern Virginia in June never cools down entirely). Or, in the words of Valentino Rossi “The bike feels good so I start to push and the tire starts to slide but it is possible to pass so I win…thank you very much.”
Most of my “street tires on a race track” experience comes from riding stock bikes at press launches with the stock tires. Often it is ridiculously easy to over tax the struggling stock rubber. These street tires, however, were surprisingly good. After getting up to speed on the R1 I did a few aggressive laps. Even pushing harder the tires held up admirably. Eventually I was throttling hard enough to get the rear spinning but this was with some pretty aggressive twistgrip work. The resulting slides were very predictable and did not seem to be causing the tire any undue stress in terms of tearing or wear. The front tire scared me a couple of time with the that soft, alternating hand pressure sort of vagueness and a couple of good old fashion chatters but most of that was remedied by dropping the tire pressure from a street oriented 36 psi to a little more sporting 33. I thought that the tires would start to shred from the amount of continued abuse we were collectively handing out but the Dunlop crew did not even feel the need to change any of the tires during the lunch break and, actually, the tires were still feeling good all the way to the end of the day.
The tires coped very well with the lower powered bikes like the R6, the GSXR 600 and the RC51 but the GSXR 1000 easily overwhelmed the available traction on the back. Even on the GSXR 1000 with the rear tire lit up the slides were sort of fun and sporting, not violent and scary.
I am reluctant to point at the tires as the cause of either the good or bad handling of any of the bikes we rode because, really, there are so many variables involved in motorcycling handling (geometry, suspension, tire pressure) that I am reluctant to point the finger and make a call on that. The R1 felt really planted and stable, the 748 felt awful, the GSXR 600 felt really light and nimble, the R6 had a pronounced over steer, the RC51 had great front end feedback, the GSXR 1000 spun the rear everywhere. I think all of the faults could have been tuned out of the bikes with time, effort and interest, except probably the spinning on the GSXR 1000, that is probably a constant.
Out of respect for the assemble Dunlop dignitaries I did not subject the tires to the more smoky sorts of street tire antics. After all, one has to exercise a certain amount of discretion around the patent holders.
These tires are not race tires. They do not have the grip or the confidence of race tires but they are perfectly adequate for a quick track day pace which makes them complete overkill for the street. They would make a great choice for a rider who uses the same bike for street riding and track days and does not want to swap wheels depending on the destination of the weekend’s ride.