| MIATA BUILD |
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 | |  | May 15, 2007 - As part of a discussion on tools to carry on the Targa Newfoundland message board, it was recommended that we carry a spare tire.
I hadn't been planning on it because, well, that's an extra 30 lbs or so that I didn't want in the car. But it might be a very useful 30 lbs.
The first step, of course, is to see if we actually can carry a spare. Uhoh.
entry 176 - tags: tires | | |  | May 15, 2007 - The tire in the previous picture was a 225/45-15, the tire size I'm favoring for the race.
This is a 205/55-14, identical in size to my second-choice 205/50-15. In a number of competitions, I've walked away swearing I'd never want for rubber. But the smaller size is 3 lbs lighter (rotating unsprung mass, the worst place for it) and, as you can see, it fits in the trunk. The larger rubber will fit in the trunk if I make some small alterations to the sheetmetal though.
Some advise against running too much tire in the Targa for more resistance to hydroplaning and more grip on gravel, but even a 225 is a smaller tire than a lot of cars will run. I want the sheer mechanical grip of the larger tire. According to Toyo's measurements, the 205 has a tread width of 8.4" when mounted on a 6.5" wheel. The 225 has a width of 9" on a 7.5" wheel. We'll have 7" wheels, but how much of that extra width comes from the extra wheel width? So many questions.
entry 177 - tags: tires | | | May 16, 2007 - More tire thoughts.
I spent some time on the phone with Joe Woodward, a fellow racer who just finished the One Lap. His day job sees him at the Tire Rack and he used to run Spec Miata, so he's very well suited to answer questions.
He noted that in direct comparisons between the 225/45-15 and 205/50-15 RA-1s, the smaller tires were actually faster on a Spec Miata. This could have been due to lower rolling resistance, as Specs are relatively low-powered cars. But he reports that the car is easier to rotate with the smaller rubber. This could also be a power-related artifact of course. Still, between the lighter weight and these reports, perhaps I should rethink my 225 obsession.
Other tire suggestions were the Yokohama A048 and the Michelin Pilot Cup. They're both considerably more expensive than the RA-1, but it's worth investigating.
entry 178 - tags: tires | | | May 23, 2007 - Okay, the wedding is out of the way.
Some good discussion on the Targa forum has reinforced my decision to run the Toyo RA-1 or possibly the upcoming R888. We'll see about the latter, availability may be a problem as it's a brand new tire for North America.
Over the course of the wedding weekend (essentially a 4-day BBQ with a short ceremony stuck in the middle), Eric got a chance to see the Targa Miata for the first time. Good news, he fits in the co-driver's seat and I was able to sort out the location for the footrest.
Time to get back to work.
entry 179 - tags: tires, ergonomics | | | May 26, 2007 - I got an email from Ander Tenno about tire selection.
He's tried both the R888 and the RA-1 on his car in the past, and here's what he has to say:
The short summary is this: the RA-1 gives up very little grip in optimal circumstances (~20-25 C sunny weather with heat in the tires) to the R888 while being significantly better in the wet and when the tires are cold. If the RA-1 was still available in Europe, I’d be still using those.
It certainly sounds as if the RA-1 would be the better choice for the Targa! Thanks so much for the feedback, Ander!
entry 182 - tags: tires | | |  | June 16, 2007 - So, after a final wander around the car, Brandon and I bolted on some wheels.
Okay, in the rear we fixed the alignment of the brake lines, then we bolted on some wheels and lowered the car to the ground.
It's funny. I work around Miatas all day. There's another one in the garage parked by the Targa car. But as we dropped the white Miata down on to the ground, it looked smaller. Much more compact than its usual stance of being nearly 2' in the air, that's for sure.
The suspension currently consists of "whatever I could find sitting around", and I suspect the rear springs came out of a late 1996-97 car while I know the fronts are from a 1990. There's a bit of rake going on. It doesn't matter, the car rolls and suspends. Its best angle is from the rear quarter, where the white roll cage is most obvious.
The wheels are a +30mm offset with 225/45-15 tires. I'll be running +20 offset with 205/50-15 tires, so the outer edges of the tires are in the correct place with this setup. The car looks good. Very white.
entry 213 - tags: tires | | |  | July 1, 2007 - I spent the weekend working on another Miata.
Janel's little supercharged Miata is now turbocharged. The operation was a great success.
But that doesn't mean the Targa Miata was completely neglected. The new tires (Toyo RA-1 in a 205/50-15 size) came in so I had them mounted up. The wheels are some white SSR Competitions. Hang on, they never came in white! Ah, but they did in Japan. These date back from a previous race effort that was sponsored by SSR Japan. They're a custom 15x7 with a +20 offset, and are perfect for this application. The fact that they have a little tricolor stripe that happens to match the Martini colors is simply icing on the cake!
entry 228 - tags: tires, other cars, Martini | | |  | July 1, 2007 - Wheel weigh in time.
The white wheel is the race setup. The graphite one is a Kazera KZ-M with a 225/45-15 RA-1. The weight difference? Just over 5 lbs! The white SSR package showed up between 28 and 29 lbs on the scale, the KZ-M was a solid 34. Not bad, but that extra 5 lbs is significant.
entry 231 - tags: weight loss, tires | | |  | November 4, 2007 - An unfortunate finish to the day.
Bill took the Targa car out to see how it was working, and I borrowed his Westfield. The little car was working beautifully and I was quicker in it than I had been in the Miata. With 700 lbs less weight and only a bit less power, that's not a big surprise. Bill wasn't lagging too much, though, and some slower traffic bunched us up. Shortly after getting free, we entered turn 5, the best turn on the track. It's like a baby version of Eau Rouge, as one driver pointed out - an uphill corner with a nice compression at the bottom and a blind exit. Very entertaining and nicely quick. I came out of the series of bends and noticed Bill was gone from my mirrors - and there was a big cloud of dust on the inside of 5 with a Miata shape inside. The car had stopped just short of a flag station and tire wall.
Back in the pits, we saw the typical damage for an off-track excursion around here - one tire pulled off the wheel and another with grass jammed in the bead. There were some scuff marks and scratches on the nose as well.
We pulled the wheels off and headed for the local Discount Tire. I was still wearing my driving suit, and when I got out of the truck a little kid asked "are you a racing car driver?". Not really, but I'm trying!
The staff at Discount were really helpful, getting right to work despite the fact that it was the middle of a busy Saturday. They pulled off the tires, vacuumed them out (to our great amusement) and reseated them in about 4 minutes. Then we were called in to have a look at the balancing machine. One wheel was wobbling badly. There are custom-made SSRs and can't be replaced, nuts. It's a good thing that I have access to a total of 8-12 of them.
Oh well, we figured we'd see how it felt. After all this, the tire shop didn't even charge us! Note to self, always wear Nomex to a tire store. Thank you Discount.
Back at the track, the tires went on and I headed to the track for some gentle exploratory laps. Heading down pit lane, I noticed that my steering wheel was off center. That was it, I headed for the trailer. Between a potentially shaky wheel with some damage and unknown suspension problems, it was not time to go push hard.
Nothing was obviously bent under the car although it appears one of the caster adjustment cams might have slipped. I didn't get the chance to mark the suspension settings before loading on to the trailer, unfortunately, and this simple change may account for the steering wheel offset. I'll check that out shortly. The paint damage is all on the lower half of the front bumper and should be easy to fix.
A sad finish to the day, but nothing that can't be repaired fairly easily and nobody was hurt. We never did figure out exactly what happened to cause the off, from looking at tire marks I think the car simply ran out of grip, possibly brought on by a slight crest in the track there. This is why we test on the track instead of the road, though!
entry 336 - tags: testing, other cars, tires, crash | | |  | July 25, 2008 - A big yummy stack of Toyos arrived today.
Yup, those are the race tires. I'll mount them up and scrub them in, then stash them away to await the trip to Newfoundland. Right now, I'm trying to pace the wear on the current tires. There are three track days and an autocross between now and the race, and I want them to wear out on the last lap of the last track day. I'd hate to pull off a set of tires that still have life in them. Right now, they're in great shape.
entry 500 - tags: tires | | | September 22, 2008 - The Toyos worked out well.
The RA-1, of course, is a very friendly tire that doesn't surprise the driver at the limit. I drove well within those limits over the week, with a couple of exceptions where I took advantage of every bit of grip available to me.
In the wet, the car was great. It's almost a shame we didn't have more wet stages, as it turned out that we were very competitive under those conditions. I don't have much wet weather racing experience (and all of that came over the course of the Targa!) so I was quite reassured at how well the car worked there.
The R888 tires might have been stickier and I certainly saw them on a number of cars. Tire wear wasn't an issue for us at all, so they'd be a good option. I'd want to know how they work in deep water first though.
entry 608 - tags: post-race, tires | | |  | October 15, 2008 - These tires have all seen three days on the Targa plus an autocross.
They look good enough for another year! I have race tires everywhere in the garage now - the six Targa ones plus the four I used for testing.
entry 636 - tags: tires | | |  | January 14, 2009 - There was an announcement of a tire rule change for the Targa in 2009.
R compounds - such as my Toyo RA1s - are no longer allowed. In fact, the tires must have a wear rating of at least 200, which gets rid of a range of popular sticky street tires such as the Falken Azenis and the Bridgestone RE01R. There's an exception for cars built before 1950 and those with stock 10" tires. The number of tires available to be used for the event has also jumped from 6 to 8, although with the harder required rubber that's not a big deal.
This means I'd probably end up running on a Hankook Ventus R-S2, although I haven't done a big search for other options. It would also make it much harder to meet the target times, which is probably the goal. Is it an improvement? Well, it's certainly a change.
entry 646 - tags: tires, regulations, 2009 | | | September 5, 2010 - Whoops.
I figured out what was wrong with the car yesterday. Yesterday morning I'd set the tire pressures and found them a bit low. At one point during the day, I tried pulling a bit of pressure out just to see how it worked. It seemed to get a bit better but I was still chasing the handling.
Just to confirm, I went back to my notes to see what the hot pressures should be - and I'd mistakenly set the cold pressures about right for the hot pressures! Even better, it was cool that morning and the day got pretty darn hot - up to the mid-90s. So that explains what was going on. On the first, relatively cool session I was probably pretty much dead on until the tires started to take temperature. And my second lap was the fastest. On later ones, as the track got hotter and I started taking more aggressive warmup laps to get heat in the tires, they were getting badly over-inflated.
I've dropped the pressures down to my usual track starting point now. We'll see how well it does at the track this weekend. I suspect much better! Boy, is my face red.
entry 762 - tags: tires, handling | | |
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