RE-71R experiment?

Z1NONLY

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?

Owen

Care.

Somehow you will need to try and control for camber.

O

Z1NONLY

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.

chrischhorn

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.

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j-rho

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

AK370Z

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



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.

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stuy486

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.

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Z1NONLY

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.

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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'17 Titan Bone Stock

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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j-rho

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.

Robert Yuras

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!