The Five-Percent Difference

The 190/55 rear tire makes an impression.

In our previous DOT-race tire test we used 180-sized tires exclusively on the 6.0-inch rear rim of the YZF-R1, and that was the choice of most racers at that time. Using a 190/50 tire, with its low profile, sacrificed too much steering quickness to offset any increase in traction the wider tire could theoretically offer.

For this test, however, Metzeler, Pirelli and Bridgestone supplied 190/55 tires. This slight increase in section height gives the 190/55 tire on a 6.0-inch rim a profile closer to the 180/55 tires used on 5.5-inch rims. According to Rich Munson, Metzeler/Pirelli's Logistics and Racing Manager, "The big advantage is the tire has more contact patch [and] also that the profile remains the same as our 180/55ZR17 fitted on a 5.5-inch rim. We wanted to recreate the same feel and grip characteristics that have given us the success we have had with the Supercorsa 180/55ZR17 but on a 6.0-inch rim. By increasing the contact patch with the 190/55ZR17 we have also created a tire that will wear much better than the 180/55ZR17 on the same 6.0 rim. This is important to us with the current horsepower numbers that the new 1000's are putting out."

While a 190/50 has a wider, flatter profile, the 190/55 is almost identical to the 180/55 but on a larger scale to fit a 6.0-inch rim. This should have a positive impact on grip, wear and steering characteristics over the 190/50 or the 180/55 on a 6.0-inch rim.

From the subjective and objective results of the test, the use of 190/55-sized rear tires on the GSX-R may have had a big influence on the outcome.