SportsCar tests: Toyo Proxes RR

SportsCar tests: Toyo Proxes RR

SCCA / SportsCar Magazine

SportsCar tests: Toyo Proxes RR

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If you’ve been around the racetrack, you’re familiar with Toyo Tires. Toyo produces a robust lineup of popular, proven, DOT-approved R-compound competition tires under the Proxes name. Toyo’s R888, R888R, RA1 and RR tires each serve a specific purpose, but only the RR specializes in on-track performance in dry conditions. For our needs, we were interested in dry weather performance – but that’s getting ahead of ourselves.

The difference between the RR and the likes of the R888, R888R and RA1 is that the RR features no tread pattern, save for a pair of symmetric grooves and a series of 4/32-inch depth holes. Tires with even the slightest of tread patterns will disperse water, but in turn, tread blocks reduce a tire’s contact patch and add squirm, which can be unnerving at speed. Conversely, taking to a wet track with a tire void of tread can be a dangerous exercise in frustration. No rain was in the forecast for our race weekend. Oh, sorry, getting too far ahead again. Lets back up.

The Toyo Proxes RR is not a new tire. In fact, the RR was unveiled in late 2012, but back then, its production was limited. Initially, Toyo offered the RR in three sizes: a 205/50-15, 225/50-15 and 275/35-18. Today, the RR boasts an incredible selection of sizes, from the tiny 205/60-13 to a gargantuan 325/30-20. In fact, in the past year, Toyo rolled out a variety of new RR sizes targeting late model muscle cars, expanding the RR’s offering to a total of 26 sizes over seven wheel diameters. Of them, the 235/40-17 fit our racecar perfectly.

Toyos are known for their durability and consistent speed, and this is what attracted us to the brand for our two-hour endurance race. Durability was key, as the racecar being used would be an SCCA T4-class Nissan Sentra SE-R Spec V. The T4 Nissan sports an in-class minimum weight of 2,750 pounds, per SCCA’s General Competition Rules. And being front-wheel drive, most of that weight sits on the front tires.

The two-hour SCCA endurance race we entered required a minimum of a single five-minute pit stop. In amateur road racing, five minutes is hardly enough time to add fuel, so our T4 Nissan would run the duration of the race on the same tires without a rotation. A true tire torture test.

The Toyo RR is designed for camber. Lots of camber. While the R888 and R888R operate best in the -1 to -3 degree of camber range, Toyo says the RR’s ideal camber begins at -2.5 and goes through a mindboggling -5 degrees. SCCA’s T4 rules limit camber at -3.5 degrees, so we prepped our car to that limit.

The RR likes more tire pressure than its Toyo siblings. Toyo states that the ideal hot tire pressure range for the RR runs from the high 30s to low 40s. The R888 and R888R both cap out with ideal tire pressures around 38psi. We set our pressures cold at 35psi front, 40psi rear, allowing for more pressure growth in the front as the race progressed. Higher initial rear pressures would also free up the back of the car.

According to Toyo, all of its R-compound DOT competition tires operate best in the 160-220 degree F range. In past testing, we’ve discovered our T4 Nissan will spike front tire temperatures above that, but sustained, our car fits within the range.

To test the RR’s absolute durability, we set to running the duration of the two-hour endurance race with an SCCA National Championship Runoffs-winning driver behind the wheel (err, that would be me), with instructions to run every lap like it was qualifying. For two hours. The only break the car’s components would receive would be during the mandatory five-minute refueling pit stop.

To capture data, we outfitted the Nissan with an AiM MXm data system. While AiM’s MXm is not as portable as AiM’s Solo 2 and Solo 2 DL, building a mount and wiring power was very straightforward. And unlike the Solo 2 line of products, the MXm is compatible with an array of AiM sensors, which is how we’d previously logged tire temperatures on the T4 Nissan during race conditions. The MXm costs about $1,000, and can act as an integrated dash with various aftermarket ECUs if you so choose, making it a very versatile and affordable unit.

Over the course of the two hours of racing at Buttonwillow Raceway Park in Southern California with SCCA’s Cal Club Region, our racecar logged 49 laps around the 2.92-mile circuit. The first stint consisted of 30 laps, with a solid 2:12.346 time logged by the completion of the first flying lap – a time that turned out to be about average for the first stint. The first stint’s fastest time of 2:11.505 came 19 laps in.

The first flying lap time after the refueling pit stop was a 2:12.517; five laps later, the fast time of that stint stopped the clock at 2:11.935. Tossing out anomalies (like when the car unexpectedly exited and reentered the racing surface), the average lap time from the second stint aligned accordingly at a few tenths off the original pace. Basically, the drop-off in lap time over two hours was minimal.

Looking at the AiM data, cornering g-forces stayed consistent for the duration of the race. Lateral g-forces were always in the 1.1-1.15g range, with braking g-forces at or around 0.9g.

Beyond the numbers, the Toyo RR tires maintained a consistent feel, with the driver only having to vary his lines and braking points slightly as the tires heated up. Tire wear was also respectable. The rear tires emerged from the experience virtually unscathed. In fact, the right side rear tire looked barely used. Being a front-wheel-drive vehicle, the front tires took the bulk of the abuse, yet life still remained. In fact, while we would be hesitant to put these tires on the front for another race, we would certainly consider rotating the tires front-to-back and competing in a 30-minute sprint race.

The Toyo Proxes RR did not disappoint. They took two hours of brutal, pounding abuse and the tires never waivered. In fact, the abuse was so bad that the car actually finished the race with a cracked brake rotor due to the intense heat – which may explain the lap time differences. The enduro also saw our T4 Nissan drive off track twice, with a handful of two-offs during the event, hopping back onto the track with a thud each time. The tires, meanwhile, didn’t care.

Finally, let’s talk price. The RRs are very budget friendly. A price comparison at TireRack.com shows that the Toyo RR in our 235/40-17 size rings up at $245 each. Tire Rack sells a comparable Hoosier A7 or R7 for $302 each, and a BFGoodrich g-Force R1-S for $288 each. That difference in price paid for the gas we used on track.

Will we race on Toyo RRs again? These tires proved they could take a pounding for multiple hours with nary a complaint – so yes, we will race on Toyo RRs again. In fact, we’re already eyeing our next SCCA event.

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