jonlugod

Bridgestone Motorsports on Board for 2015!!!



I am proud to announce that Bridgestone will be on board with us for 2015! We will be displaying the performance of their new Bridgestone Potenza RE-71R Extreme Performance Street Tire throughout the year and expect big things with this partnership. Not to mention Bridgestone is offering a Contingency Program for Solo Championship Tours and the National Championships in Nebraska in September.





We've all seen the tire comparisons to their previous model and have concluded our own observations in the past. The data provided to me from our Time Attack teams we work with in Japan suggests that this tire is the one to beat. Nearly all of them switched from Hankook RS3 or Yokohama Advan AD08R to the Bridgestone noting a decent increase in performance from a S-Tire (street tire lingo in Japan).



In terms of size, there was some concern in what its actual size difference would be compared to our 285/35 Hankooks. As you can see above, the difference is very minor and the construction of the tire is much more rigid in comparison to the Hankook.





In the past the release of the Bridgestone Potenza RE-11A caused some stir in tire legality due to the fact that early release tires did not have the treadwear rating molding on the tire sidewall. This was later clarified by both the SCCA and Tire Rack that early batches of tires typically have a 6 month grace period and that the ratings are indeed done prior to release. (Appendix F). We wrote our own treadwear rating to poke fun at the issue .

conemark

A fly on the wall says that the RE-71R may have made the favored Toyo "so last week" and that the other tires (D & H brands) aren't quite the ticket either.

Inquiring minds would like to know!

jesup16

^ I've been hearing similar feedback, but rather it's more on par with the "H-brand". This was feedback based off a different car, in different tire sizes, and based out of FL, where it was very warm. H brand tends to like the heat.

chetly

Any pictures of those tires on the rims Jon?

jonlugod

This is both mounted on a 18x10.5" rim.

RE71R Review

Take it for what this is. We are sponsored by Bridgestone Motorsports but I will give you my honest opinion about the tires as I too hate biased opinions.

Noticable things:
What I noticed was it only took half a lap to scrub all the mold release off. Granted we did have a 70 second course during our practice on Saturday. I took a total of 7 laps without watering and noticed that the pace did not fall off. I also noticed that the tire did not feel greasy leading to the 7th run. We had a good 5-7 minutes in between runs which seemed about typical for an autox.

Using a tire probe pyrometer I found 34psi front / 32 psi rear to be ideal for our setup. The shoulders on the tires are very stiff and provide great feedback to the driver. Reaching the tire's limits seemed easier and more welcoming than previous tires. Putting power down was no problem considering the downsizing from 285 to 275. This is a big step towards street tire performance and should be a good option for Street and Street Touring alike.

Response:
The tire is not quite laser accurate as the previous tires; however, makes up for it with confident grip. The tire just grips and communicates well when the limit is reached. Its by no means Hoosier grip but it definitely is a large step forward in bite.

Tire Wear:
Wear seems pretty good after a total of 15 runs over the weekend. Nothing alarming in that regard. On our CS FRS, the Bridgestones seem to handle the lack of camber pretty well. We figured that help comes from the stiff shoulders. Will report wear as the runs come and go. Next event for us is San Diego Tour.

This video was of my 3rd run. I accidentally set the GoPro to photo burst mode for my 4th and fastest run =(. I made a mistake coming into the first slalom on this run. Managed to take the win and my Co-Driver took second 0.010 seconds behind!

chetly

Nice, I didn't see where it was mentioned that those were mounted tires. I'm liking what I see.

Ramo7769

It would be very interesting to see some data on the RE-71R compared to the RS3 (and ZII*). I'm sure a third party will test soon, but it will be even more interesting to see 285 RS3 vs. 275 RE-71R... vs. 285/30-18 ZII*. I guess I could do it myself. Just need to spend several thousand dollars in tires.

jonlugod

We found a consistent .4xx-.5xx second difference between our RE71R and RS3 between two drivers. We had one guest alien driver drive the car a couple laps on the RS3 trying to get within the .5xx of my time on RE71R. That's what we found with our setup, on that day, with the timing equipment.

dale3guy

Did each driver run on both sets of tires and see the difference? Or did one driver use the RS3's and the other use the RE-71R's? How many runs were on the RS3's?

Xian

FWIW, there were a bunch of point end folks who ran the RE-71R last weekend. Every single one of them picked up time on the Bridgestone over the RS3. That's not to say that the RS3 is a "bad tire" and I'll go further to say that all the comparisons I know were in apples to apples size comparisons. If you can get a substantially larger RS3 then it may be the faster tire.

<--- staring at his Z2 SS's in the garage and waiting until after 4/30 to pick a final tire.

jonlugod

Yes both drivers drove on both tires.

Alien driver drove on RS3 only.

There were about 75-80 runs on the RS3.

alextz

Cool Thread!

This would be (C5 STU) a fun project. BTW, I think you guys are way too stiff on spring rates. Street tires don't have the transitive grip to handle. I use way less on the SSP car.

I totally think the C5 Z06 is an SSP national winner (taken me 3 years to dial in my car not being able to spend as much time on it as I wanted but managed to have fast time on East course 2013, close on the rest, coned a 2nd place overall last year), but it has the shortest wheelbase of C5, C6, and C7 which makes it turn! Once you get to the 400+hp at the rear wheels, traction can get limited in a hurry, that is why for autocross speeds (less than 70mph), more power doesn't get you much (unless you have 4wd, but then you have 400-500 lbs more weight). The weight of the C5z is extremely low to the ground.

Hoping to be at Spring Nationals this year. not sure what to do about A7s because if the 335s run wide, then I will have to run more spacer in the back to not rub. Of course it snowed here 4 inches in Chicago this morning, so I won't find out anytime soon.

Alex Tziortzis

Ramo7769

I tend to agree. But, if you're not familiar with VB&P rates, the figure may sound inflated compared to what it actually is in practice. Their rate is derived from center mounting the spring and deflecting both ends at once.

I am running 1100 lb/in front / 825 rear VBP rates (not wheel rates) on my STU C5 and plan to make my way to Nebraska this year also. I like where my rates are at, personally, but I have to deal with my stock differential contributing to off throttle understeer currently.

conemark

Just curious if there is any further feedback post the San Diego National Tour:

Particularly, what is the wear looking like for the RE-71R for a relatively heavy and powerful C5 on what is admittedly a rough surface?

jonlugod

OS GIKEN – SCCA STU CORVETTE
SAN DIEGO NATIONAL CHAMPIONSHIP TOUR



Just a recap of how things went this past weekend in San Diego. The event was the SCCA’s second Tour Event of the National Tour Series leading up to the National Championships in Nebraska this September.

Saturday:
The car was well prepped as it could have been for that day. Grip seemed low after the first runs and seemed to get worse after each run. The pavement started to lift up and certain sections were looser than others. I was able to build off each run and take a quick clean time for the day and have a two tenth lead heading into Sunday. Below is a link to the Official Event Publication for Saturday with a quick interview of me after STU ran.
http://www.solomatters.com/2015-san-...saturday-recap




Sunday:
For the second day of competition the course is now ran in the opposite direction. This proved challenging as the dynamics of elevation change and camber loss from the Qualcomm surface was more apparent at speed. A lot of people were hitting cones and proved to be very challenging. I made some shock settings for day 2 and got some grip back into the car.I had two first runs in which the course caught me by surprise. By my third and last run I was able to throw down a decent run, however I lost my lead from day 1. In the end I lost to my competitor by .352 of a second.
http://www.solomatters.com/2015-san-...ur-event-recap




Next Event: SCCA NATIONAL PRO SOLO SERIES ROUND 1 at El Toro, CA (March 27-29)
My next event will be this coming weekend where I plan to redeem myself from this past weekend. It is a drag start/mirror course layout (similar to Gymkhana). I am working on the suspension this week in preparation for the event and look forward to the competition. If you care to follow you can watch live results at: http://sololive.scca.com

jonlugod

Tire Wear



Tire wear seems to be the main topic with people evaluating the Bridgestone RE71R. Here is what out tires look like after 40 runs.



The center rib measures at 6.5/32 still while the outer blocks are at 5/32. Decent wear for a heavy car with the ability to achieve proper alignment and roll rate. I project the car should be able to get about 120 runs or more out of this set.



This is an example of our tires, on our car, with our setup. YMMV (your mileage may vary)

conemark

Thanks for the update JL. Even though I'm still playing in the R-comp space, it's important to know how the new kid on the block will fare.

jonlugod

El Toro Pro Solo


Ended up taking 1st in STU at the end of day 2 competition. Very tough competition battle between myself, my co-driver Michael Oest, and 2014 CS National Champion Jeff Stuart. The car worked well and only needed minor shock adjustments from Saturday morning runs. The suspension has changed quite a bit so here is an update:

1020 in/lb VB&P Front Leafs
740 in/lbs VB&P Rear Leafs
Strano 33mm Front Bar on medium setting
Z51 Rear Bar

Camber changed from -2.8/-1.3 to -3.0/-1.7. This changed the behavior quite a bit and allowed me to put power down from mid corner to exit. I think i want to experiment going to -2.0 in the rear to see how far i can go. I'm debating reducing caster from 7.5 to 6.5 as i can feel the car weight jack quite a bit when turning the wheel past 120º. May experiment going back to Stock C5 rear swaybar (19mm). Overall a great weekend and the competition definitely has made the class step up in speed. We were the fastest ST class and my times would of placed pretty well in other faster classes (SP/SM). Can't wait to go up to Crows Landing for the remaining West Coast National events!

Ramo7769

Ah, your spring rates are more similar to mine now, but lower now. Mine are 1100 front and 825 rear. What's interesting to me is that I use the stock front bar and T1 rear bar to balance the car. I think some of that may be due to the inherent low speed understeer that I haven't worked to remedy. I have the stock diff which promotes understeer and zero front toe. It's loose on the track in this setup but still stable at Solo speed.

I'm surprised by how well your car rotates. You likely have more front roll stiffness than me and I have a lot more rear roll stiffness. I'm running 285 Dunlop ZIIs square on Z06 rears. My alignment is a bit different at camber of -2/-1.5 and 7.0 deg caster.

strano@stranoparts.com

Front bar is 2 way adjustable, unless Jon modified it. Which setting? I'm going to assume maybe the softer one since you didn't say full stiff.

I'm glad to be a part of it.