RE-71R experiment?
 

The new RE-71R "street tire" from Bridgestone seems to be running and more importantly wearing, like a race tire with a tread pattern...and a 200 treadwear rating to make it "legal" for the street-tire classes.

Many people seem to be reporting accelerated wear over previous street-tire offerings from various manufacturers. I would like to quantify this in an experiment.

I'm considering:

1)Fitting a Miata (small, cheap tire sizes) with RE71R's on one side and RE-11A's on the other.

2)Use a traction circle and a pyrometer to set appropriate air pressures for each pair of tires.

2)Constructing a symmetrical course and running it in both directions, repeatedly, with consistent drivers. (-making sure that each driver splits their directional numbers evenly)

3)Document wear with before and after tread-depth measurements and pictures.


*IF* there is a huge difference between two different tires that a single manufacturer has rated with identical tread-wear ratings, then I think it's fair to say that Bridgstone was incorrect with its treadwear rating process/number and the exclusion list should be considered.

If the RE71R's wear similar to the RE11A's, great. But if there is a gross difference in wear, the SCCA has an exclusion list and the RE71R should be on it.

I fear that allowing tire manufacturers to stamp "200 treadwear" on the side of a compound that isn't even close...without repercussions...will be bad for autocrossing.

So, before I bother to set up this process:

-Does anyone even care?

-What other variables should I try to control for?

Care.

Somehow you will need to try and control for camber.

O

I am considering getting the alignment checked before and maybe even after, but all I would be looking for is symetry from one side to the other.

The pyrometer should show what's going on with the contact patch.

I care especially because I have an STS Miata but you are correct in previous driving done from other forums. The RE-71R is basically an R-compound with a 200 TW rating. PROBLEM is that the TW number is not regulated in any way or by any one other than the company themself. A 200 TW tire from bridgestone can mean 10k miles wear while a 200 TW tire from Michelin can mean 30k. Its just to compare to each manufacturers own tires so if the RE-71R's get 200 TW and get 10k miles. Their next tire like the S-04's can get a 300 TW rating 25k miles worth of wear.

Why do you think randomly once the 2014-15 rules were announced about the 200 TW rule for any Street class that all of a sudden the RS3's, the RE-11's, the Direzza's and the Toyo R1-R's all randomly became 200tw. They didn't change anything on the compound but yes I'd love to see some testing of how the RE-11's and the RE-71R's compare. I'm running RE-11A's on my Miata right now.

There's going to be enough people driving them on different cars, the real longevity story will be evident soon enough.

You want RE-11 vs RE-71R comparison? :tup:

http://i576.photobucket.com/albums/s...psdaztsw13.jpg

If I had a pair of rear sports pack rims, I'd do it. I have a pair of extra front rims but no rear rims. The Re-71R just showed up on Friday.

TireRack already conducted a back-to-back test of these two tires.

There's no talk of wear in that test, but I don't think you're test is going to answer that question either. There's a lot of factors that go into it, I think it's a pretty car-dependent issue. On our STU 350 we're not seeing wear that's crazy. We've got ~500 highway miles, 3 TnT runs, 12 Tour runs, and 24 ProSolo runs on them and they're looking fine so far, we're confident they'll make it through the next Tour and ProSolo events just fine. Are they wearing faster than a Hankook would? Probably, but it's not as bad as people are making it out to be.

Got about 400 street miles and 14 Prosolo runs on mine, they look good. That's with a 3200lb. 370z on skinny little 245-18's all around.

My expectation for street tire wear - and what I used to get on my STS 240sx back in 2006 - was 10 ~60 second runs (or ~10 minutes on the clock) per 1/32" of tire. Will have to measure depth on these to see how they're doing, but so far they appear to be in that ballpark.

The time difference is similar to what Ruggles experienced between RS3's and the RE71R's.

It's huge.

However, the most recent pro solo didn't show the same disparities.

So which size is everyone using on the front? The 245/40? or the 255/35?

And why the heck dont they make a 295!? GRRRR. I want 265 front 295 rear!

On the stock sport rims I'd run 275/35r19 square.

whoa are you guys on RE-71R too? or talking about RS3 v2? haha if you guys are RE-71R, we need to create a Potenza club! haha ..

My first event on them (RE-71R) this Sat. They are at 0 miles right now. Just curious, what tire pressure did you guys end up with? I was thinking 38F/35R?

I ran these psi settings on my 285/35 rivals and have already torn off chunks of tread off the outside of the fronts, I wouldnt recommend these tires to a stock 370z with the little camber we have. going to try the new kumho when it comes out if the re-71r wears too fast

I was just looking into these since they seem to offer the sizes I want 265/305 19

if you know Japanese it may help......:bowrofl:

クãƒ*ホタイヤジャパンæ*ªå¼�会社 - タイヤラインナップ - ecsta V700

the sizes it shows are:

225/40/18
245/40/18

235/35/19
245/35/19
265/35/19
305/30/19

also in 17, 16, and 15 as well.

blog post on the kumho as well for any interested. just copy paste into Google translate. all in Korean.

금호타�어 블로그 Dr_tire

Both on Bridgestone RE-71R.

Pressures depend a bit on the rest of the setup. A stock no-camber car with a 275 stuffed on a 9, will need a lot more pressure than my STR car with -4 degrees and a 245 on a 9.

I've heard some advise to not go below 35psi with the Bridgestones. I ended up with low 30's front and high 20's rear but again, everyone (and every surface) is different - gotta experiment for your sitution to find what's best.

38/35 seems like a safe starting point.

To me, the Bridgestones are head-and-shoulders above everything that was already out - R1R, RS3v2, Z2*spec, etc. However there's still the BFG Rival-S and Kumho 720 to learn about - the former has started shipping and the latter is supposed to this month.

What j-rho said about pressures being car/setup specific.

On the 350 STU car we have 275s mounted on 11" wheels with -4° camber, so obviously a different situation compared to the same tire mounted on a 9" wheel with -.7° camber. We were running 30 PSI and weren't even getting close to the arrows/triangles on the sidewall.

Thanks guys. Good to know.

Drove around on RE-71R a little bit tonight. It feels less responsive vs. RE-11. Even I was on 285 sq with RE-11, turn in were crisp. I put like 39F and 37R. I will have to play around I guess at venue. I am guessing the sidewall is def softer than RE-11 walls. But grip feels much more. But again, it's just butt dyno. I won't know until I do a few events. I plan on chalking the side and using infrared temp gun to check across tire. I will know more next couple events.

You Southern and Coastal guys have such a seat time advantage! I'm planning to start the season in May with the RE71-R's in BS. Will report back for all.

Ok, how then do we go about answering that question?

What's to stop Hoosier from stamping "200" on the side of their A6 and saying "there is an official test that we conducted that proves this to be 200tw.....trust us."?

If proving that two tires with the same tw rating wear at very different rates is not proof of a false tw, rating what is?

TW testing is conducted by an independent lab/facility and establishes the maximum tw number a manufacturer can put on the tire. The manufacturer may choose to put a lower number on the tire if they choose however. This is why in the autox world lately there have been a number of tires that have gone from 180 to 200 tw. Those tires were really 200 tw (or maybe even higher) tires all along even though they were marked otherwise.

You also need to remember that while somewhat related, tw and gripiness of a tire are two different things. Currently there is no industry testing for rating the gripiness of tires.

This was all from a discussion 2 days ago I had with a tire engineer from Cooper Tire.

I have heard this rumor before but never seen any solid information on it.

Do you have a link or something?
This is from tire rack:

"When looking at UTQG ratings it is important to realize that the Department of Transportation does not conduct the tests. The grades are assigned by the tire manufacturers based on their test results or those conducted by an independent testing company they have hired. "

So the tire makers can do their own tests, report whatever thay wish, and roll the dice on someone calling the government in before they change /drop the tire in question.

Like I said this was all from a conversation with a tire engineer from Cooper Tire.

Here's a link from wikipedia that explains the testing though: Treadwear rating - Wikipedia, the free encyclopedia

From what I have always heard, is that the standard is not closely regulated by the DoT. So it is difficult to compare the TW ratings from one company to the next. But when looking at just one manufacturer you would think they would have a metric they base each their tires off of and thus the consumer can use that information when considering to purchase tire A vs tire B. If they are really stamping 200TW on a tire just to meet a regulation for a competition that is not good business. If I was a competitor at the manufacturer level you better bet if the TW continues to go unregulated. I would have to follow suit to make sure my sticky compound meets the requirements set forth by the competition's governing body so that I meet the demand of that market.

Here's the problem:

UTQG Treadwear Numbers: What Do They Mean? - Motorsport Messages from Marshall | Tire Rack

"UTQG treadwear numbers are published by the manufacturer based upon their test findings of a tire's life expectancy. It's important to note that not all manufacturer's standards are equal and similar ratings may lead to different real world results between similar product types."

I used to work for Goodyear in the early '80's. I know back then. Each manufacturer had they own testing standards. No two manufacturers were a like. The manufactures tests each other tires to see were they stand with their own. They also back engineer the tires too. Nobody is pulling the wool over their eye anymore. As far as tread wear and temp ratings. The manufacturer puts on what they feel is a representative number after testing.

Got to play with the RE-71Rs at the NCM Match Tour this past weekend. The lot was pretty new asphalt with a dusting of sand. Laid down 4 TnT runs and 14 Match runs. Ended up running 39-40psi front and 33-34psi rear, with Koni's at ~75% front and ~80% rear. Took the trophy in BS on Saturday, but lost in the Sunday semi's of the club shootout. The tires were fantastic all weekend. Lots of grip, good audible feedback, and heat up quick even running first in the mornings (more than my R-S3's did). However, by the 5th shootout run, which were only about 3 minutes apart, they were greased. I ended up with a DNF coming out of a 180 sweeper into a slalom....front end pushed and hit the first pointer while holding the same line as previous runs.

How is the wear?

So far good. We'll see what Wilmington does to them in a month or two.

Which Wilmington event are you referring to? I'll be at both pro's and the tour.

Congrats on the win! I was just happy to be somewhat competitive considering my tire handicap. :)

The Wilmington Spring Pro is capped. The two Toledo's line up with family commitments, so I'm looking at the Wilmington Summer Pro and Match.

Relevant podcast on the latest tires: Podcast episode 47: 2015 GRM Tire Test| Grassroots Motorsports | forum |

YES!!! I'm not the ONLY one with similar setup!!!! :tup: Do you have any videos of your runs?

I am on 275/35-19 re71R and run EXACT same pressure 39F and 34R cold. I have rear 8/10 stiff and front about 5/6 stiff (and looks like I should bump it up half a turn maybe?). Everyone tells me to do otherwise (super soft rear and stiff front and honestly, I didn't like it at all.)

Question, do you have any trouble getting grip in super super smooth asphalt venues? I'm experiencing a little under-steer or lack of front end grip with this setup in just ONE of my three venues? other two venues I'm fine. This venue has a slippery super smooth newly sealed asphalt. In this venue, would you soften the front koni a bit or stiffen even more to 80-85%?

I have a bit of info on the wear of the tire, I'm on these for a daily tire as I frequent the dragon. They are wearing much faster than the RE11 for me but I typically run 33/30 cold pressures. May try bumping them up a bit and seeing how they react.

This is the first tire I've ever owned that sounded like Velcro peeling off the road everywhere I drive. That doesn't mean it's that sticky, it just makes a weird noise.

:icon17:

I think our setups are very similar. I have 275/35-19 RE-71R too and Koni's and Eibach front sway full stiff. I just got back from the Utah Match Tour in Farmington, UT. It was a new location I guess and it has new asphalt. I was only able to place 4th on the first day and missed out on the shootout. However I got randomly drawn into the bonus shootout and finished 2nd there. In regards to your comment I noticed these tires weren't fans of the afternoon heat which was hovering around 100 degrees, I'm not sure what the surface temp was. Traction dissipated and the surface was slick almost grease like. I think they're awesome tires and they're wearing quite nicely. I have 24 runs on mine and probably 200 miles of actual street use on them. They have this weird 45 degree wear thing going on though which I guess is normal because other local drivers are experiencing the same. Still good amount of meat left.