TESTED: Achilles GS-328 Race Tire

Achilles Tire R1-X review test

TESTED: Achilles GS-328 Race Tire 
by Steve Rockwood
I've driven on a lot of tires, some of them horrible, some of them great.  All of them have been DOT legal. Until now. When we were approached by Achilles Tire to try out their new GS-328 racing slick on Project G20 Racecar, we predictably jumped at the opportunity. 
All of us who've been to a track see the slicks on the 911 GT3s and other expensive race gear and drool. With those tires, we often think, we could conquer the world and wipe the floor with the competition, but no way they'll last, nor could anyone that doesn't have a race hauler and pit crew afford it, right? Luckily for the everyman, Achilles has stepped up to the plate and introduced their GS-328 slick at an everyman's price point, and it was up to us to see how they performed.
Achilles Tire R1-X review test Team CRE Catfish
Team CRE has been running the Achilles GS-328 on their ESR Class "Catfish" CB01-R for their successful 25 Hours of Thunderhill endurance race.
Currently, the only size offered for our 15" wheels was the smallish 19/57-15, which was exactly gibberish to me until I did some research.  Translated to US-centric tire sizes, these are basically the equivalent of a 195/50-15 tire.  Reading it directly, this is a 19cm wide tire that is 57cm tall, designed for a 15" rim.  For even our relatively lightweight G20 (2500lbs with driver and a full tank of fuel), these tires were still a little undersized.  This size would work perfectly under a Miata or CRX, especially given the gear reduction from the shorter tires, and the available 24/61-17 would've been much better suited to our car and its weight if we had 17" wheels available.
Achilles Tire R1-X review test width comparison
Giving up 35mm of section width to the 225mm tires we usually run, the Achilles GS-328 had its work cut out for it.  Doubly so when you consider that all of our competition runs 245mm tires.

Team CRE Achilles R1-X Test
The 24/61-17s that Team CRE was sporting would've suited our relatively portly G20 much better than the 19/57-15s we ran.  However, we did not have any 17" wheels available to mount the larger size.


Achilles Tire R1-X Sizing Test
Never seen this sort of sizing convention before?  Neither had we.  Roughly converted to US-centric sizes, this compares to a 195/50-15.  The 19 refers to width in cm, the 57 refers to the height in cm, and the 15 refers to rim size.


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Friday, May 24, 2013 5:43 AM
How you think these things would do under a really lightweight car at an autocross? You guys said you had issues before they were up to temperature...The A6s just wear out too quickly, and I've been looking for an alternative among all the R-comp tires.
Friday, May 24, 2013 6:50 AM
@ Hudson: No issues with them before they got up to temperature, just issues with them before we had properly cycled them in.

I wouldn't do an autocross on a set that I had just mounted and not driven on, but if I had a chance to scrub all of the mold release off of them, I wouldn't hesitate to use them. These tires, at 190mm, were one of the grippiest tires I've ever used, and that includes 235mm R-compound tires.
Friday, May 24, 2013 1:43 PM
Also available are 27/65-18, 27/68-18, 30/65-18, 31/71-18
Friday, May 24, 2013 3:22 PM
"The 19 refers to width in cm, the 57 refers to the height in cm, and the 15 refers to rim size."

To clarify slightly (and if it wasn't obvious), the 57 refers to the overall height of the tire, not the sidewall height like a typical (US) tire size. You would have to take out the rim size (in cm not in, in this case 15in=38cm) and divide by two (since you have two sidewall heights in the overall height). That would make the 57cm tall tire have a 9.5cm sidewall height.

Of course this doesn't compare directly since US sidewall height isn't a unit but rather a ratio of tire width. A 195/50-15 would have a sidewall height 50% the size of the 195mm tire width, about 97mm or 9.7cm.

However, that is complete crap since you can have 10 different 195/50-15s lined up and they are all different in sidewall height.
Saturday, January 04, 2014 10:15 AM
Need moar updates for this project car, please!
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