Testing the Dunlop SP Sport 9000 DSST

In order to evaluate the performance, comfort and durability of SP Sport 9000 DSST tires, the Tire Rack Team conducted a "Real World Road Ride" comparing a vehicle equipped with properly inflated tires to a second vehicle with a "flat" front tire and a third vehicle with a "flat" rear tire. We used 225/50R16 sized tires mounted on 16"x7.5" wheels fitted on 1999 BMW E46 chassis 328i rear wheel drive sedans.

While it seems a bit unusual to let all of the air pressure out of a tire on two of the vehicles before beginning our evaluation, that's exactly what we did. We wanted to confirm a flat Dunlop SP Sport 9000 DSST tire's ability to maintain vehicle mobility for up to 50 miles at up to 55 mph, and to learn how Dunlop's DSST tires would feel on the car when properly inflated, as well as, how they would affect the vehicle's handling when one tire was flat.

Dunlop SP Sport 9000 DSST - Externally, the Dunlop SP Sport 9000 DSST shares the directional tread pattern and tread compound of Dunlop's "HydroMax" SP Sport 9000 tire. Its unique design features many relatively narrow "vanes" to help pump water to the sides of the tire to resist hydroplaning, and a tread compound with high silica content to increase wet traction without significantly compromising dry traction. The Dunlop SP Sport 9000 DSST earns the highest UTQG traction rating of "AA" confirming its excellent traction on wet roads.

Internally, the Dunlop SP Sport 9000 DSST tires feature a radically different construction. First, the traditional steel belts have been replaced by angled aramid belts (aramid is smoother riding and pound-for-pound, stronger than steel). Then the traditional nylon JointLess Band (JLB) spiral wrapped reinforcement around the tire's circumference (which helps stabilize its tread area and provide the tire's high speed capability while reducing weight and enhance ride quality) is also replaced with aramid cord to further enhance ride quality during the first few miles of driving after the vehicle has been parked long enough for the tires to cool. SP Sport 9000 DSST tires earn a W-speed rated, 168 mph capability when properly loaded and inflated.

The Dunlop SP Sport 9000 DSST tire's casing sandwiches rubber between layers of heat resistant rayon cord in the sidewall to give the tire its "self-supporting" capability by helping prevent the sidewalls from folding over on themselves and "pinching" their casing cord in the event of loss of air pressure. Finally, specialized beads incorporating Dunlop's Max Flange Shield (MFS) allow the tire to not only firmly grip current Original Equipment and aftermarket wheels even in the event of air loss, but also helps protect the vehicle's wheels from curb damage when parallel parking. Dunlop SP Sport 9000 DSST tires must be fitted in sets of four and can only be used on vehicles equipped with a low pressure warning system approved by Dunlop for DSST tires.

Our evaluation of the Dunlop SP Sport 9000 DSST tires actually began before we got into the cars. Casual observation of the cars didn't immediately identify which tires had no air pressure. They just didn't look flat! The DSST tire's "self-supporting" structure only allowed the tires to appear low on air pressure, even when there wasn't any.

On the road, properly inflated Dunlop SP Sport 9000 DSST tires were praised for their low noise level, real world handling and unexpectedly good ride quality. Our previous experience with Dunlop's SP Sport 9000 HydroMax tire has shown that it is one of the smoothest and quietest tires in its category. Surprisingly, adding the "self supporting" construction to the DSST version of the SP Sport 9000 has only resulted in a slightly harsher ride quality which is rated as average for the Max Performance tire category.

The vehicle with a flat front tire made itself known by making the steering feel "heavy" at parking lot speeds and a little slower responding to driver input at higher speeds. Additionally, the flat tire generated a slight "pull" to the side as the vehicle continued to be driven around our 7 mile test loop. Many drivers might not connect the vehicle's subtle driving symptoms with a completely flat tire.

While the vehicle with a flat rear tire didn't affect its performance during gentle driving, when the driver initiated faster steering input at higher speeds (like a relatively quick lane change or when driving on a winding expressway ramp), a flat rear tire would allow the vehicle to yaw uncomfortably, and feel "loose." Knowing that the tire was flat allowed the driver to anticipate and appropriately react to the vehicle's motions.

All of these flat tire conditions confirm why a low tire pressure warning system is required. The low pressure warning system is intended to alert the driver that one of their DSST tires has lost inflation pressure to below that recommended by the vehicle manufacturer. In addition to letting the driver know he has a problem which should be corrected as soon as possible, this warning also lets the drivers know that gentle driving at reduced speeds may be called for. Ultimately, failure to heed this warning may result in total tire failure and/or loss of vehicle control.

NOTE: If the vehicle is pulling a trailer when the low pressure system activates, the driver should pull off the road gradually and slowly, stop safely and unhitch the trailer until repair or replacement of the tire can be accomplished.

During our evaluation we confirmed Dunlop's claim of maintaining vehicle mobility for 50 miles at up to 55 mph by running eight SP Sport 9000 DSST tires without failure or incident. Remember: Driving at the lowest speeds permitted (never over 55 mph) and minimizing the distance traveled after being alerted by the low tire pressure warning system may improve the opportunity for successful repair of Dunlop DSST tires.