Tested: Toyo Proxes RA1
By Steve Rockwood
It seems the RA1 has been around since before time began. Ask an “old timer” (well, relatively) and they'll tell you that the RA1 was the holy grail of DOT competition tires. A decade ago, a walk through the hot pits of any track event would net you rows and rows of RA1-shod cars. Times have changed, but have they passed the RA1 by? We installed a set on Project G20 Racecar to find out.
First, we need a little background on why RA1s are still available. A couple of years ago, Toyo did the unthinkable and took the nearly ubiquitous RA1 and replaced it with the slightly more capable, but less forgiving and faster-wearing R888. While the move made sense from a lap-times and progress perspective, many lamented the change because they felt it did not represent the same dollar per lap bargain and ease of use that they enjoyed with the RA1. Luckily, Toyo decided to re-start production in 2010, and it was immediately written back into nearly every NASA spec class rulebook.
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| Favored among racers for over a decade, the Toyo RA1 is still a relavent R-compound tire, but is it competitive against today's latest offerings? |
So, what made the RA1 such an awesome tire that it could be brought back to life today despite all the recent offerings from competing companies? The RA1, like all tires, is all about compromise, and it achieved what is considered by many to be the ultimate in compromise: excellent grip and feedback, easy to drive to and beyond the limits, and iron-like wear (relatively speaking, that is). Add in the fact that the tires will continue to be consistent all the way through the rubber until the chords show, and you'll see why so many racers loved the RA1.
A look inside the construction of the RA1 reveals a strong inner carcass that offers firm shoulders. The carcass itself is unidirectional, so tires can be moved left to right, giving the RA1 a distinct advantage over purely directional tires since most tracks tend to abuse one side of the car more than the other. Keep in mind that when on the “wrong” side, hydroplaning resistance will not be optimal since the tread itself is directional.
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| While the tread pattern is directional for water evacuation purposes, the inner tire construction is omnidirectional, allowing you to rotate tires left to right, as well as re-mounted on the rim to offset cars that abuse the outer treadblocks. |
The tire itself is optimized to operate at temperatures between 160°F and 220°F. Recommended alignment settings are between negative 2.5° and 5.0° camber and as much caster as possible (within reason, of course). Depending on static camber and vehicle weight, inflation pressures are recommended to stay in the 37 to 44psi range. On our G20, with 3° of negative camber up front, 1.75° of camber out back, and a race weight of 2550lbs, we started at 38psi hot and adjusted to keep temperatures consistent and handling balance in line. Our final pressures ended up at 40psi hot front and 42psi hot rear. The higher relative rear pressure was partly due to the poor camber gain from our G20's McStrut rear suspension and to allow the car to slide more easily.
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| With three degrees of negative camber and a race weight of 2550lbs with driver, we settled on 40psi front and 42 psi rear to keep temperatures even across the front tires, and to help the car rotate on the less-stressed rear tires. |
The tire comes new with 8/32″ of tread depth, and many shave them to 4/32″ where the lateral grooves disappear. Optimal dry traction begins at 6/32″ and will continue all the way past when the tread mostly disappears at 3/32″ down to the chords. Be careful with full-depth Toyos and a heavier car, as the tread can “chunk” on you if pushed too hard when new.
