WHich Tire would you Choose for the Pro Solo and why?....

[mec51]

POS Racing said "some of us" should give posting a try - so here goes my attempt....

Average driver piloting a 2007 MX5 MSR underdawg in BS in Mineral Wells and have the choice of running an "almost new" (11 AX runs - no street miles) DZII's (235/40/17) OR a brand new set of RIVAL S (225/45/17) - both mounted on KOSEI 17 x 7 wheels. Some data points with both tires mounted for your consideration:

225/45/17 RIVAL S	235/40/17 ZII
78.75” Circumference	77.25” Circumference
8.5” Tread Width	8.5” Tread Width
39.5 LBS	38.8 LBS
Theoretical Top Speed in 2nd = 69.1*	Theoretical Top Speed in 2nd = 67.5*

*Per Flyin Miata Gear Calculator

So with your experience + the GRM article + this data in hand + anything else you may want to factor in - which tire would you choose and why?...

Thanks in advance for any thoughts!

PS – have pics but not posting rights at this point….

[POS Racing]

POS Racing said "some of us" should give posting a try - so here goes my attempt....

I'm so proud!!

[jrj512]

Assuming that the DZIIs are not the DZII Star Specs, then go with Rivals S.

[hornetball]

Emilio just posted over on MT.net that the Rival-S is just shy of a Hoosier in the grip department. Better than 100TW tires like RC-1, NT-01, RA-1. Perhaps on par with an RR in grip (not in feel). It also wears really quickly, so 200TW? Emilio is track focused, not Auto-X focused though.

[sammm]

I really liked the set of Rivals I had. My next set of tires will most likely be the Rival-S's.

[wrx74]

Try them both this Sunday at ER!

[OZMDD]

Rival-S. No question.

[CosmosMpower]

Emilio just posted over on MT.net that the Rival-S is just shy of a Hoosier in the grip department. Better than 100TW tires like RC-1, NT-01, RA-1. Perhaps on par with an RR in grip (not in feel). It also wears really quickly, so 200TW? Emilio is track focused, not Auto-X focused though.

If that's true it's pretty crazy. Toyo RR is close to a R6. Are they using R compound rubber and pouring them into street tire molds now?

[mec51]

Thanks for the feedback guys!...

Assuming that the DZIIs are not the DZII Star Specs, then go with Rivals S.

The 235/40/17 are DZII Star Specs purchased in April of this year

Try them both this Sunday at ER!

If I can get them all out there without a trailer - I'm going to try to do this!...

One additional piece of the puzzle is that this car is a 5 speed - so I am wondering if the smaller diameter of the ZII and the acceleration it might provide over a "taller tire" would offset the benefit of the incremental grip offered by the RIVAL S?...
Thnx again!

[mec51]

Just an update to this thread based on running both tires (DZII Star Spec and RIVAL S) at MW this weekend (thanks for a great event ER!....)

Left Side: was about .4 seconds faster with the BFG's in the afternoon session (never really got this one right...)
Right Side: was about .75 seconds faster with the BFG's in the afternoon session (felt like I was a little stronger on this side...)

The Rivals were brand new, not even scuffed in so I think there is even more in them - if I would only learn how to drive.
Thnx!

[hornetball]

If that's true it's pretty crazy. Toyo RR is close to a R6. Are they using R compound rubber and pouring them into street tire molds now?

I think that may well be what they are doing. I read somewhere (everything we read on the web is 100% accurate, right?) that production of both the Rival and Rival-S moved from the passenger-tire lines to race-tire lines (where they build the R-1 and R-1S). According to what I read, main driver was to improve the quality of the tread splice since I know BFG had a lot of warranty costs from chunking/delam at the tread splices (every Rival I've ever had ended up showing its tread splice and I've had a couple that chunked there). But, the rubber compounds available on the race-tire line are the R-1 and R-1S compounds, so . . . ??

[CosmosMpower]

So is the Rival-S rubber compound essentially the R1-S compound with tread?

[OZMDD]

No, that is not the case, just another example of internet speculation run amok. They moved production to the race tire facility for QC and logistics purposes, according to people who are genuinely in the know.

[hornetball]

just another example of internet speculation run amok.

That should be my middle name. LOL.

[CosmosMpower]

No, that is not the case, just another example of internet speculation run amok. They moved production to the race tire facility for QC and logistics purposes, according to people who are genuinely in the know.

Ah ok, better QC is good but I don't see how the tire magically gets Hoosier fast in 1 iteration.

[hornetball]

This was Emilio's post. You can see that the Rival-S wears quickly, so it's a pretty soft compound:

http://www.miataturbo.net/wheels-tir...2/#post1234926

[OZMDD]

Agreed, it is very soft.

[sammm]

Agreed, it is very soft.

But it's still 200 TW, correct?

[OZMDD]

As much as that number actually means anything, yes. Its interesting that people are so up in arms about this issue. The same was said about the Toyo not lasting long enough to be a true 140 tire, yet that has proven false. How about the original Falken Azenis? They were useless once they heat-cycled out, with plenty of tread depth still on the tire. Also, the argument that they defeat the purpose of "street tire" classes, which was to reduce tire budgets from Hoosier-levels: Many of the popular sizes are as cheap or cheaper than the previous generation of street tires, and they still outlast R-comps in the number of competitive runs by a factor of 3 or 4.

Its true that you aren't as likely to milk 2-3 seasons of autocross out of a single set of tires al-la-Peebles, but even a hardcore regional competitor should be fine with 2 sets of tires/year, and that is assuming you don't take them to the cords, maybe even swap them at 75% used. On a miata, that's around $1-1.2k/year for the 15" sizes.

And the current crop of tires is a streetable as pretty much any tire in the segment since 2005, other than the Z1 Star Spec, which was an exceptional daily tire.

Anytime you feel like the new tires are "basically the same" as R-comps, hop online and price out a set of equivalent Hoosiers, and then figure out how many sets you need to buy to get the same number of competitive runs. Lets be generous and say that Hoosiers are good for 30-40 competitive runs (I hear its more like 20), and be conservative in saying that the Rival-S and RE-71r are good for 90 competitive runs. That's still 2-3 sets of purple crack for every set of new street tires, and you can't drive to/from the event on Purple crack.

I think this is just another thing to gripe about, rather than a meaningful issue.

[Robert]

I tend to be in the “they’ve gone too far” camp. For me the RS-3’s were the sweet spot for performance/wear, but I will deal with it.

For me A7’s are $50/set more than BFG’s.