RE-71R experiment?

j-rho

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.

stuy486

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.

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AK370Z

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.

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nismosis

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.

Z1NONLY

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?

gomer_110

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.

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Z1NONLY

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.

gomer_110

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

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speedfreek

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.

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Z1NONLY

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."

Rusty

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.

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nismosis

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.

Z1NONLY

How is the wear?

nismosis

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

Attached Images

tires.JPG (66.4 KB, 44 views)

gomer_110

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

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