Cal Club Autocross Forums

We're still trying to decide on our wheel/tire set-up for our Miata running in the SCCA Time Trials and SV Miata Challenge.

The Miata Challenge uses a Mod Point system to classify the car. We need to stay at 9 points or under to run in the Street Class (and no R tires).

The thing is that Dunlop Star Specs with their 200 wear rating only cost us 2+ points, while the Hankook RS-3's are 4+ points, because they're 140 wear.

Now we know that Wear Ratings are determined by the Manufacturer and don't really follow any really common objective testing. If we go with the Star Specs (205/50/15, 7.7" tread width) we can go with an 8" wheel (1+). In order to use the RS-3's, only available in 225/45/15 (8" tread width, shorter side wall) for our wheel diameter, we would need to go with a 7" wheel (0 points).

We've already used up points by having coil overs (2+), an LSD (1+), NB (1+ vs. NA), Cold Air Intake (0.5+) and non oem header and exhaust (0.5+). We gain back a half point for Safety Gear, ie. seat, harness and fire extinguisher.

Are the RS-3's that much better then the Star Specs? We ran the Star Specs a couple of years ago on our Miata and loved them. Two years ... THAT IS A LONG TIME ...

It's hard to tell since you are comparing different sizes. However, if sizes are the same RS3's are better in my opinion, with the only issue being that they are not very good in the wet.

I will use the starspec if the points savings can be used to go for wider tires along with the 8" rims.

For track use, I think the Hancooks would handle the heat better. If it's wet, use the Dunlops.

And the Toyo R1R ... for dry, wet and cold ... until the summer heat starts up?

The Toyo's are available in 205/50/15 and 225/45/15

Sounds like the 8" wheel and 205/50/15 might be the size compromise.

Some Miata Challenger's say we might want to lose the Intake and Exhaust mods so we can use a 8" wheel with the 225/45/15 Hankooks. Tire/wheel size being the most important mod. Apparently the only track where a thinner 205 tire would be an advantage would be the long straight at CA Speedway's Roval layout, and perhaps Willowsprings.

Having driven my old NA on Henry's 225 RS3 setup, I would say that you should do whatever you can to copy him. Amazing grip.

Mako Koiwai wrote:...Some Miata Challenger's say we might want to lose the Intake and Exhaust mods so we can use a 8" wheel with the 225/45/15 Hankooks...

Agree.

Ug ... so much work to change back that light weight exhaust manifold and exhaust system to gain the point back to allow us to use 225's and 8" wheels. We've already sold the 9" wheels to Tim ... but not delivered or paid for yet.

It would be easier to just go into the Modified class ... but then we would be at the bottom of the Mod Class, ie. we would then need to spend the $1K for an ECU tune ... which we can't afford at the moment. Buying new helmets, racing seat(s), harness bar/harness, etc.

I drove Steve C. STS Miata with 225 Hankooks ... yeah ... surprisingly massive grip , especially compared to our worn our 225 Toyos