Toyo R1R Extreme Performance Tire Review.
As tire technology and manufacturing become more sophisticated, new rubber compounds and tread designs are pushing the limits of a tire’s capabilities. As an example, there are off road mud tires for 22-inch diameter wheels that are designed to be just at home in the mud as they are in providing a smooth and quiet ride on the highway.
In the same manner, Toyo’s newest D.O.T street/race tire, the Proxes R1R, is truly a racing tire that has greater capabilities of existing on the street. To people like SCCA racers and street driving enthusiasts, who would rather spend money on their vehicle’s suspension instead of a paint job or stereo system, the concept of a D.O.T approved street/race tire is not new. In the past, enthusiasts have had to use a tire that sacrificed extended tread wear and wet handling characteristics found in street driving, in exchange for the higher levels of dry handling needed for autocross or other racing venues.
The Toyo R1R’s technology provides a more balanced design that brings the capabilities of a true dual street/race tire to a higher level. You typically don’t find much of a tread pattern on a D.O.T approved racing tire as they tend to deflect under hard cornering and lead to instability. But to improve the street capabilities and minimize hydroplaning, Toyo engineers had to find a method to add tread that would not deflect under extreme racing conditions. They accomplished their goal by adding a variety of technologies to the R1R.
The first was to improve the contact patch of rubber to the pavement. This was done by altering the tire’s casing design. This changes the tire’s shape, providing a wider footprint that maximizes the contact patch, making the most of the tire’s width. They also added a high-grip rubber compound that is infused with silica, to reinforce the tread blocks to prevent deflection. The chance of tread deflection is further reduced by rounding and angling the leading edge of the tire’s center blocks to add stability and decrease the chance of irregular wear.
The elimination of tread deflection allowed Toyo’s engineers to design a tread that would improve the tire’s wet performance. Water evacuation channels start from the center of the tire and extend outwards, similar to many directional tires, but the channels narrow towards the tire edge. This design improved wet traction and stability to really make the tire more capable in street driving conditions, without truly sacrificing its race-inspired characteristics. The addition of stability control slits on the tread, also provide resistance to irregular wear during aggressive braking and help channel out water in wet conditions.
Extreme high performance tires such as this also require a stiff construction to provide stability, quick response, and crisper handling to give the driver a better “feel” for the track. To accomplish this on the R1R, Toyo added wide high-tensile steel belts and improved the tire’s bead with a high-modulus apex compound.
If there is any compromise that the R1R is guilty of, it’s the tire’s overall tread life. Although the silica-infused compound does provide longer life than other tires in its class, the R1R wears more quickly than a standard street tire, especially when under regular abuse of racing. But for all the advantage that this new tire has, the shorter life is definitely a good trade off for improved lap times and being able to drive your vehicle safely to the track.
We tested a set of 245/40R18’s on our project Mustang GT and put it through its paces on a short, closed autocross course we set up. From the start, the R1R’s provided more road feel over the factory 235/50R18 street tires. Although the tires provided a comfortable ride, you can feel more of the road, especially when driving over potholes and large grooves.
Under hard cornering, the tire allows for great driver sensitivity back through the steering wheel. After a few times around the course at speed, the tire’s stability and predictability come into play. It was easy to predict the tire’s limit of traction on our vehicle, which was still equipped with a stock suspension. We could only imagine how much more handling improvement we could gain with the R1R’s once we add on a performance suspension system with adjustable control arms.
Under hard braking, the combination of the tire’s tread pattern, silica compound and the vehicle’s ABS allows for smooth stopping under control. The stickier tires also aided in traction under hard acceleration which improved our course times as the tires warmed up under hard use.
Fortunately, the weather cooperated with plenty of rain; enough for us to test the R1R’s capabilities on some backroads. Some of the roads we took have numerous pockets of water build-up that we attacked at 35-40 mph. Although the tread pattern’s EVAC channels are not as efficient as a fully directional rain tire, they are a huge improvement for a tire such as this. At our test speeds, we didn’t experience any hydroplaning until we hit several pockets of deeper water. However, driving on the freeway, we felt confident driving beyond the speed limit (defined as 56 mph), under hard downpours and didn’t experience any minute loss of control or slippage.
If you live in a cold climate, be forewarned that the R1R’s softer compound will crack at temperatures below 32-Degrees F. The rubber compound has properties that can cause to them to loose some of its flexibility when stored in sub-freezing temperatures. So unless you are racing in Alaska or in the northern parts of the country, the tires should be stored in a warm environment.
Overall, we were pleased with the performance of the R1R’s that provided excellent performance both on an off the street. Currently, the R1R’s are only available in 16-18-inch diameter sizes in 35/45and 50-series designs.
