Mark Houlahan
Tech Editor, Mustang Monthly
April 14, 2015
Photos By: Courtesy Of Bridgestone/Firestone

Any time we get an invite to hit the road course and try some hot new performance rubber for our Mustangs we’re in. We recently had the privilege to visit Wild Horse Pass Motorsports Park (formerly Firebird International Raceway), the home of Bob Bondurant’s School of High Performance Driving, as a guest of Bridgestone Tire.

Bridgestone has a long history of performance and a great reputation amongst enthusiasts and motorsports fans with its Potenza brand. The original Potenza RE71 launched in 1985 and over the last three decades has been continually improved, starting with the standard center-rib design of the RE711 in the late 1990s and then moving to the asymmetrical design of the RE-11 in 2008. The RE-11 was updated to the RE-11A in 2012, keeping the asymmetrical tread design. The RE-11A has a well-deserved reputation as a perfect autocross or track day tire that you could leave on your performance car for everyday use. So could Bridgestone improve on that? We were about to find out first hand behind the wheel!

Bridgestone’s latest ultra-high-performance (UHP) tire harkens back to the original RE71, using a symmetrical construction with a directional tread pattern. The new high-grip polymer compound, along with the return of the wide center rib design, offers a dramatic increase in grip by increasing contact area by 15 percent. The soft compound of the RE-71R literally grips around the road’s textured surface. The reinforced, extra stiff sidewall and massive tread block shoulders help with cornering. In Bridgestone’s testing of the new RE-71R, both wet and dry cornering, and wet and dry lap times were improved over the RE-11A.

The Bridgestone Potenza RE-71R is currently available in 33 sizes and in 15- to 19-inch wheel diameters. Additional sizes will be launched later in 2015 and throughout 2016. Check out the technology notes and images below, as well as the accompanying video for more on our time with Bridgestone’s RE-71R, as-well-as Bridgestone’s Ecopia EP422 Plus and DriveGuard run-flat tires.

As this Bridgestone graphic shows, the new directional tread pattern, sticky compound, and wide center rib of the RE-71R translate into excellent handling, acceleration, and braking.
When it comes to wet performance the RE-71R does an admirable job of drainage, but this is a ultra-high-performance summer tire, so caution should be exercised around standing water or torrential rains.
While not the ’15 Mustang we hoped to hot lap, these Scion FR-S models were fun rides and their 200 hp boxer-four engines gave us enough oomph to push the Potenza RE-71Rs and get a good feel for the amount of grip they have.
Our track day festivities also allowed us to sample Bridgestone’s new Ecopia 422 Plus low rolling resistance tires. These new tires are designed to save fuel on your family sedan (like a Ford Fusion) by allowing you to travel a farther distance on the same energy input from the engine. The Ecopia 422 Plus is available in 42 sizes in 15- to 18-inch diameters, which covers 80 percent of the market.
We were really impressed with the Ecopia 422 Plus in wet weather testing. The competitor tire induced massive push/understeer in wet cornering while Ecopia 422 Plus allowed us to take the corner not only at a higher rate of speed, but with more confident handling and no push.
These custom trikes, fitted with Ecopia 422 Plus, allowed us to experience the improvement in rolling resistance from the previous model tire by pedaling to a certain point and then letting the trike coast. It was fun and educational!
Our last tire we drove was the DriveGuard, Bridgestone’s answer to the run-flat tire market. The DriveGuard has been available for a little while, but Bridgestone wanted to ensure we were familiar with it. The tire allows a consumer to drive up to 50 miles at 50 miles per hour to reach safety even after complete air loss. The all-season type tire offers a quiet ride and unlike traditional run-flat tires includes a 50/60K mile treadwear warranty and ride quality comparable to a traditional tire.
As seen here, our driving instructor is removing the valve stem core from the wheel to simulate a complete loss of tire pressure on the left front DriveGuard tire on this sedan.
With a complete loss of air pressure you can see there is only a small amount of tire sidewall deflection, which is why it is imperative that a run-flat tire only be installed on vehicles with tire pressure monitoring systems (TPMS). Without TPMS it is really hard to tell there’s air loss with the tire. We drove this sedan at speeds reaching 45 mph and unless we cornered hard to the right, we had no idea the tire was flat, and even then the tire only became noisy but the car remained stable.