JSC Speed's 1993 Mazda Miata Project Car
I wasn't thrilled by the wheels or tires that came with the car--a set of used Falken Azenis RT615s and a set of Hankook RS2s on bronze Konig Heliums (shown on the car on the previous page)--so I sold the Konigs w/ RS2s and put that money into a set of Enkei Racing RPF1s. I chose the RPF1s because they are the lightest wheel you can get for reasonable money. My 15x7 RPF1s weigh in at a scant 9.5lbs each! I also got lucky because I managed to snag a set of the limited edition black RPF1s that Enkei Racing only makes a few sets of each year (when they make them).
My tires of choice are the 205/50-R15 Toyo R1Rs, but because they were very hard to get (brand new tires in a brand new size) I wrapped the wheels in the partially used up RT615s that I gotten with the car. The Falken rubber was considered an excellent high performance tire a few years ago (and still is a decent tire for the money), but they are nowhere near as sticky as the Toyos were promising to be. I did get the Toyos mounted onto the RPF1s in the middle of July and wow. The 140 UTQG is a little misleading as these R1Rs (shaved to 5/32 from 9/32) feel stickier than other 140UTQG tires, for sure.
As of September 2008 I've done eight autocrosses, an Evolution Performance Driving School, three days on Pocono and a few thousand street miles on this set of R1Rs. The hardest part of running these tires is getting the tire pressures set up right. Miatas on Falkens and Bridgestone RE-01Rs run somewhere around 32-36psi cold, while I'm now running about 22psi to get the most out of this tire. Initial reports from some well known Miata runners said that the R1R was graining and falling apart after a few autox runs. It turns out they were trying to use them at the RE-01R pressures and it was killing the rubber. I've gotten to where I know what the pressures need to be now--now that the season is almost over.
In late April '08 I took the Miata to its first Philly Region SCCA autocross to give it a shakedown. Overall, the way the previous owner had the Miata set up the performance and handling were pretty good. The Miata rotated pretty well--almost too well in fact--but the Falken RT615s weren't all that great, so grip at corner exit was less than stellar. I ended up six of nine, but I wasn't overly disappointed considering I'd never autocrossed in a rear wheel drive car before.
On my way home from the auotx I discovered that I had a blown out right rear hub, so I needed to repair it pretty quickly as two weeks later I was scheduled to take the Miata out on to Pocono East for the season's first HPDE with PDA. This was my first introduction to the aforementioned MazdaSpeed Motorsports Development, and boy, am I glad I signed up for that program! I ordered new knuckles, hubs, and bearings for both rear axles, along with new bushings for the control arms. Even with overnight shipping from California the price was almost half what my local Mazda dealer would have charged me! With the rear end all back together and ready to run was prepared for a Saturday HPDE at Pocono East (a big autocross course, really) and then a Sunday autocross with Philly again.
The HPDE was, um, foggy? Literally, lots of freakin' fog. Fog so dense you couldn't see the wall of the speedway's straight (between NASCAR T1 and T2) from East's pit road! We lost almost half the day, but still got three 20 minute sessions in before the day ended. I was a million times more confident with the Miata's on track demeanor than I was with my Scion tC's. The car handled magnificently, and the tires (still the shoddy RT615s) did okay on the first two sessions and got super greasy on the third and final stint. I was lapping with much more powerful cars without fear of holding them up (I would gap them in the corners only to have them on my bumper at the end of the straights). Passing an 05 GTO was very gratifying--I later learned he was having brake trouble, but still he had a couple hundred more horsepower than me.