How important are tires? [A tire test conducted shows you]

[flohtingPoint]

Something that goes undocumented by the tuner magazines and import culture is the severe importance of quality tires. There are a billion write-ups on engine swaps, brake conversions, body modifications, ECU tuning, blah-blah-blah, but honestly, I can tell you that the majority of that is pretty much worthless if you don't have proper shoes on your car.

Below is a tire test I conducted for SCCA members. Take note of the data logging screenshots provided and run deltas. Also, take note, that BF Goodrich Rivals (while considerably slower than an r-compound) are about 10 times better than the tires I see on most tuner's cars.
Some backstory on why this test was conducted:
-The SEB (Solo Events Board) passed a proposal that would remove r-compound tires (tires below 140 treadwear) from stock competition and create a new class division called "street" which would be basically "Stock" only with 140+ (and 200+ in 2015 and beyond) treadwear tires.
-Myself and a large number of National competitors hated this idea, as it makes our cars significantly worse to drive.
-Three National Champions and I ran my car on both A6's and street tires to get a delta from high level competitors and to get hard data from my traqmate.
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B-Street vs A-Stock Corvette Analysis
------------------------

Car:
-99 Corvette FRC
-46,000ish Miles
-Koni Single Adjustables
-33mm FSB
-Ferodo Pads
-Magnaflow x-pipe and axleback

Tires:
BF Goodrich Rivals (sticker)
-255/17 Front (32 PSI)
-275/18 Rear (28 PSI)

Hoosier A6's (35 runs before this test)
-295/17 Front (31 PSI)
-315/18 Rear (31 PSI)

Drivers (Alphabetically):
-Cormier (National Champion)
-Junior (multi-time National Champion)
-Newman
-Strano (multi-time National Champion)


Introduction:
As you can see, I'm easily the one with the least amount of accolades than my co-drivers in this endeavor (no championships, never even trophied at a Pro Solo), my cohorts have red jacket(s plural in some cases) to keep them warm in the winter, I have a long wool coat from Express. I'm also the one with the least amount of experience, as this is only my third year of autocrossing nationally and my very first year in a car. I'm bringing this up because this really makes me the "Average Joe" here, Mr. Mediocrity if you will. Since the whole justification for the "Street" classes is for your average/new competitor, I think I'm right up that alley (heck, I'm a downright n00b on street tires, I've driven on them maybe 5 times total in the past three years including this test), as nobody looks at a grid sheet and goes, "Oh, James Newman is registered, I'm screwed". My impressions of the vehicle and it's handling characteristics are what the SEB is concerned about, if their word is gospel.

To save time, I'm not going to go over our R-Comp runs, you don't need to read about how good an A-Stock car is, you just need to drive one once to find out.


The Rivals Test:
I was in charge of running/conducting the test and I thought it would be best if we did it Nationals style, meaning all four of us present, we take one run, come back, re-prep the car, put the next driver in, they make a run, come back, prep the car, put the next driver in, and so forth. While it's no mystery that both Sam and myself are not big on the idea of street tires on Corvettes, all four of us are competitors and performing this test in a competitive atmosphere like such made us all want to drive to the best of our abilities. Any notion of sandbagging to get false data from the tires can be thrown right into the garbage, Sam himself set the best time on the street tires.

Given that everyone says the Rivals get better and better with heat, I didn't put the car on a clock, the only times we halted the car were when coolant temps were getting high (Vettes get toasty, that's why you see the hood up on all of them in grid). We averaged about a run every 3 minutes going off my data loggers times. I wanted to give the tires every advantage they could get.

Sam and I set our fastest runs on the first run. Junior and Cort set theirs on their second runs respectively.

Rivals Debrief:
The infomercial for Rivals we all saw with folks talking about it handles like an R-Comp, I disagree with. The handling is nothing like an R-Comp (maybe on smaller cars this is true, but on mine it is not), I'm very familiar with what my car is capable of on A6's, this felt nothing like it. The grip wasn't bad laterally (we pulled 1+ G) by any means, but the way the tire reports the grip is completely different. I never really trusted the car (especially transitionally) and dropped it on my final run (I dropped it on my final run on A6's but that was because I was in the dirt, it was very sandy).

Going into this test with the popular opinion being that the Rivals get better with more and more heat, I drove my first run at 8/10ths to get a feel for what the car is like. I then mentally factored in that the tire is going to be better my next run and ramped it up. The tire felt the same, no better, no worse, and the things I was demanding of the tire translated into overdriving in this case. A6's come to life with each run, the Rivals pretty much stayed the same (nothing wrong with a consistent tire, its better than one that falls off). Had I known that the car would not have more grip my second run, my approach would have been very different.

Junior brought up a good point, we never adjusted the car for the street tires, and this is true. Perhaps the car could have been better, perhaps worse. Things like this take time, money and effort. This was one of the things that was mentioned in the "saving money" sales point of street tires in stock, but the amount of testing to get a full tilt "Street" class car is going to take a lot of work and a lot of time, this translates into a lot of money being spent, not saved. Talking with Borg at Spring Nationals, he mentioned he was going to try B-Street and I wish him the best of luck.

THE GOOD
-Car isn't terrible at all. If all I knew was street tires, I'd be one of the folks going "Whats the big deal with changing/getting rid of Stock"?
-You can see the friction circles for each of us, they look very similar between Rivals and A6's. As I stated before, the lateral grip wasn't bad in sweepers, I didn't quite trust it in transitions but sweeping was fine.
-Honestly, the way I ran it, I became entertained with the competition and half way through blocked out that the car was on street tires. I like competition and it was fun. While not for me, I can see the appeal for it certainly.

THE BAD
-Sam nailed it, the problem is longitudinal grip. Going off the data, the cars aren't losing much time at all in corners, it's mostly in the entrance and exits. Braking and accelerating is where the biggest problem areas are.
-Safety. During our Rivals runs, there was some concern over how hard my car was being driven. Now, I fully appreciate it anytime someone treats my car with respect and I was thankful that they were being so, but I told them that I trusted them and they should go 10/10ths. Now, when the r-comp runs came, there were no issues driving my car to the limit.
-TIRE WEAR! These were sticker tires and we took 15 runs (12 competition runs, 3 scrub in by Danny) on the tires and I drove home from the site on them (115 miles). Danny estimates that we lost about 1/32nd of tread. This may seem bad or good to some people, I really don't know as I don't know tire life well on street tires, but what is alarming is that all five of the people that drove the car are experienced Corvette drivers and know how to drive with the rear, meaning we all know how to make tires last. Someone much less experienced (ie: your novices the SEB is trying to tell that tire wear wont be a problem) is going to have MUCH worse tire wear because they will not have the skillset yet developed and will most likely be driving with the front still.

Conclusion:
It was an eye opening experience and great driving with three people I enjoy being around and learning from. I definitely learned that the car isn't horrible, which was my biggest fear. Like I said in my "THE GOOD" notes, if all I knew was street tires, I think it might be an enjoyable vehicle. Can it compete with S2000's in BS? Maybe, I'm a bit more hopeful now after driving it on street tires.

Brief touch on STU:
I think anyone who is afraid of C5's in STU should put their fears to bed, it's going to take a lot of work to get them up to the speed they need to run (again, it wasn't as bad as I thought it would be, but it wasn't as good as the masses feared). Could it be a good STU car? Perhaps, but in a pro it's going to have a huge disadvantage, giving up .4+ on each side to an AWD launch. STU's pax is .846, A-Stocks pax is .847, so we run similar times. If you compare the Rivals runs to our A6's runs, that's a lot of time to make up.

FWIW, the day before this test, Junior and Courtney were running the SSP C6Z on 335 Rivals (well past the point of STU prep) and couldn't match the times Sam and I put down in my A-Stock car on bald A6's (that most likely had about 70-75 runs on them before I drove 800 miles on them for fun and then did a school on them) in 1/3rd of the runs they took. This was also on a course that had a monster straight on it, plenty of room to gallop. Again, considering that STU needs to run near AS's times, they were still off in a rocket ship with huge street tires on it that is prepped well beyond STU levels.

Videos:

RIVALS
Strano 46.346
http://youtu.be/Yv77_X833LQ

Cormier 46.684
http://youtu.be/EYAAlzE_sl4

Junior 46.753
http://youtu.be/A5QG9Vg2juQ

Newman 47.684
http://youtu.be/BwoDUoCtXUg


A6'S
Strano 44.188
http://youtu.be/ICQ9-a2-Z_A

Junior 44.371
http://youtu.be/dBUay1CD0Us

Newman 44.701
http://youtu.be/KT-VoCSRQ0Q


NOTE: IF YOU WANT THE TRAQMATE FILE, LET ME KNOW, I WILL GLADLY DISTRIBUTE IT!


Data logging screenshots of the sectors of the course

[AZhitman]

This may quite possibly be your best work to date, Mr. Newman.

Random thoughts to follow:

I'm always amazed at the crap tires people pay good money for after doing a thorough build - but I'm even more amazed (disappointed, really) at the crap they put on their daily drivers.

Remember kids, 6 feet less stopping distance means you might not put a 6-foot-deep hole in the side of that minivan full of kids that ran a red light in front of you.

I got to test out the R1's when they first were released - I'm running the road course in a DE at Miller on a set of Nitto Invo's, and some BFG rep offers me a set of new R-comps to run and evaluate... I didn't have 17's on the car, so I also got the use of a set of brand new Volks (sadly, those had to be returned with what was left of the tires).

We were already hitting triple-digits on two sections of the track, and the tire change turned the car into an amusement park ride. With 3 drivers rotating in and out of the car, it was on-course all day. 2 tanks of gas, a complete set of pads, and an engine bay covered in P/S fluid - good times.

[elwesso]

One of the thing that annoys me with tires (especially being an engineer) is that there's really no way to quantitatively compare tires, it is all qualitative. Almost every other component to a vehicle has something that it can somewhat quantify it's performance.. Springs have spring rates, shocks have damping rates (basically an anti-spring rate), engines have HP, drivetrain components have loss factors, brakes have clamping power.

There is nothing really to quantify how good a tire is going to be. About the best thing you can do right now (for street tires mainly) is look at tire rack's user ratings, which generally are a pretty good metric to compare similar tires. We know how important tires are. Recently my dad bought a set of tires, and he told me he found a couple different sets ranging between $500-$800. He asked my opinion, and I told him that "the tires are the only thing that touches both the car and the road at the same time"..

Greg's point is right on the money. 6ft difference in stopping distance doesn't seem like too much, but you'll wish you had it when

This is interesting because it is very practical, and theoretically with the same setup it would be very easy to duplicate the same results.

Being a nerd, is there any way that you can email me the data in like an excel spreadsheet or a CSV text file or something?

[PapaSmurf2k3]

^You'd think you could basically plot coefficient of friction at different temperatures for the tires both static and kinematically. I've never seen it though.

I've had tires that grip like whoa right up until they don't, and you go spinning like a top, and other tires that break free really easily but have decent grip while sliding, making controlled drifts fairly easy.

[AZhitman]

-The SEB (Solo Events Board) passed a proposal that would remove r-compound tires (tires below 140 treadwear) from stock competition and create a new class division called "street" which would be basically "Stock" only with 140+ (and 200+ in 2015 and beyond) treadwear tires.

Here's my issue with this - Treadwear numbers are, to my knowledge, only comparable WITHIN the brand. They're not cross-applicable or comparable ACROSS brands.

So, what's to stop an unscrupulous tire manufacturer from building a run of tires, with a comparative treadwear rating of 60 (super-sticky), throwing a 140 stamping on the sidewall, and making them "underground available" to a certain subset or "preferred group" of racers?

I mean, are they testing compound hardness with a gauge before each event? James, educate a brotha.

[PapaSmurf2k3]

My guess is there is some kind of standard SAE tire test that determines tire wear rating. Possibly even a federal regulation.
Again, just a guess though.

[AZhitman]

No sir.

The assigning of UTQG grades is done solely by the tire manufacturer. In many cases, this has resulted in the UTQG grading system to be more of a marketing tool than was originally intended.

It is legal and permissible for a tire manufacturer to give a particular tire line a lower treadwear grade. For example, if the highest treadwear grade in a manufacturer's lineup is 600, then a tire line with a lower treadwear test result might receive a grade of 400, instead of the 480 it could possibly receive.

Also, it is common for tires whose treadwear grade is of little commercial value, such as racing tires, to be assigned extremely low values - sometimes even zero.

[elwesso]

Here's a couple posts I dug up from Q45tech.

97-q45-tire-selection-t3736.html
which-would-you-choose-t26607.html

Since all tread wear indexes are numbers created by manufacturers and are not checked by goverment, and they are only relative numbers to be used WITHIN brands not between brands..........they are pretty useless in comparing most tires.

The point is a 280 and a 360 may be the same or different or reversed in the real world.
Think of them as ranges: 50-100; 100-200; 200-300, 300-400; 400-500, 500 and above.........with overlaps.

Greg is such the n00b in those threads too...

I can't find the exact post, but the treadwear number basically just says how fast a tire wears compared to other ones. For instance, you would expect a 400 treadwear Michelin to last 4x longer than a 100 treadwear Michelin.

IN terms of polymers, durometer (hardness) is not the only thing that really means anything. You could make something very soft that is very wear resistant, where you could also make something very hard (relatively) that doesn't wear for crap. In the industry that I work in, we use a lot of rubber liners to line our equipment from abrasion (rocks). These liners "feel" about the same as a tire (maybe softer), but I can assure you they wear a LOT better than tires. Also, the durometer has little correlation to how it reacts to temperature (either low or high).

I come from the mentality that "A single test is worth 1000 expert opinions", so I really think the only way to have repeatable, quantifiable results, would be to have some sort of test that simulates real world driving. I'm not sure how you would do it, but it would be pretty cool to design a test.

[flohtingPoint]

-The SEB (Solo Events Board) passed a proposal that would remove r-compound tires (tires below 140 treadwear) from stock competition and create a new class division called "street" which would be basically "Stock" only with 140+ (and 200+ in 2015 and beyond) treadwear tires.

Here's my issue with this - Treadwear numbers are, to my knowledge, only comparable WITHIN the brand. They're not cross-applicable or comparable ACROSS brands.

So, what's to stop an unscrupulous tire manufacturer from building a run of tires, with a comparative treadwear rating of 60 (super-sticky), throwing a 140 stamping on the sidewall, and making them "underground available" to a certain subset or "preferred group" of racers?

I mean, are they testing compound hardness with a gauge before each event? James, educate a brotha.

Ok, this is going to take a bit to type up, and will also address some of the other replies in here. On the Metro now, will begin my tldr-fest when I get to the office =)

[flohtingPoint]

-The SEB (Solo Events Board) passed a proposal that would remove r-compound tires (tires below 140 treadwear) from stock competition and create a new class division called "street" which would be basically "Stock" only with 140+ (and 200+ in 2015 and beyond) treadwear tires.

Here's my issue with this - Treadwear numbers are, to my knowledge, only comparable WITHIN the brand. They're not cross-applicable or comparable ACROSS brands.

So, what's to stop an unscrupulous tire manufacturer from building a run of tires, with a comparative treadwear rating of 60 (super-sticky), throwing a 140 stamping on the sidewall, and making them "underground available" to a certain subset or "preferred group" of racers?

I mean, are they testing compound hardness with a gauge before each event? James, educate a brotha.

Ok, forgot to update this but am doing it now. Get ready to TLDR! I will attempt to be as impartial as possible so folks can form their own opinion.

First things first, the SCCA Solo rule book is written for NATIONAL COMPETITION only. Regional SCCA factions are allowed to do whatever they want within reason, and are not required to follow the classifications set forth in the Solo rule book.

National Competitor: Like myself, national competitors travel all across the USA, competing in big scale autocross events called "Tours" or "Pro Solos". Your typical tour/pro will contain 200+ competitors, a lot of which are at the top of their field. To do this, I typically spend about 15k per year traveling/building/sleeping/fueling/etc on autocross. Most of my spring/summer/early fall is spent in Nebraska/Arkansas/NJ/PA/Ohio/VA/MD (obviously since I live there)/GA/Indiana/etc. I typically compete in 30+ events a year.

Regional Competitor: Typically does 10 or less events within their same region. Maybe one national event if it's hosted by their home region.

Earlier this year (and without warning), but well after everyone had spent their winter money buying cars and/or doing dev on their current vehicle, the SEB (Solo Events Board) released a rules change proposal that would essentially foreclose the "Stock Class" and create a new class called "Street". Stock class is/was defined as having the legal modifications of:
-Dampers
-Tires (must be DOT legal)
-Wheels (+- 5mm offset, no change in width/diameter)
-Exhaust (from cat onwards)
-Air filter (must be contained in stock airbox though, so no cone filters)

Street class would have been:
-Dampers (Only single adjustable allowed)
-Tires (must be DOT legal and above 140 treadwear)
-Ability to tamper with the ECU to disable nannys (traction control)
-Wheels (+- one inch diameter)
-Exhaust (from cat onwards)
-Air filter (same as before)
-Camber adjustment beyond stock means (ie: camber plates, non-stock eccentric bolts, etc)

Now, the "Street" class greatly appealed to your regional competitor. A lot of them believed that you need 5k worth of dampers and sticker (meaning brand new) r-compound tires to compete every event. "Stock" class carried a stigma that it was expensive, and a lot of the regional competitors thought these items were holding them back from the bigger national competitors. The fact of the matter is, they dont need to change a NATIONAL rule to pacify a REGIONAL "problem" as regions could have made this change long ago, leaving the national ruleset intact.

Most of the national competitors I spoke with in grid were opposed to these changes. We knew that classes were built off metrics gathered utilizing cars on r-comps, and that street tires greatly changed how a car can perform (especially larger, higher horsepower cars).

Folks that are FB friends with me may have seen my posts regarding this as it was transpiring during April-Oct, as I was a big proponent in fighting to keep stock the way it was. I even plastered it on the front of my car (bonus points if you "get" my license plate):


Well, the letter writing campaigns for both sides happened, and the folks who liked "Stock" were outnumbered by, what we were told by the SEB, 5 to 1. I requested to have information pertaining to who was in favor of "Street" and if they were of National status in Stock or not. My feeling was that since the rulebook is written for national competition only, the folks that are national competitors in Stock have the most important voice, as it's our class thats getting shut down. I personally volunteered to go through all the letters and parse the contents to see how many were from national stock, and what was the REAL ratio instead of this 5 to 1 nonsense. My requests were denied, and they continued to use this 5 to 1 as gospel, when myself and many others, believe that the majority of the folks in favor of street are not national competitors and/or not in Stock (the class on the chopping block). To this day, the information pertaining to who was in favor of the stock proposal has not been released, probably never will.

Numerous revisions of the "Street Proposal" were released (camber allowance gone, ECU tinkering gone, etc), but the damage had been done, folks were pulling out of Stock, including myself. The only class that looks to be saved is a class called "Super Stock", which is where I am moving. The proposal was passed by both the SEB and the BoD (Board of Directors), even though both saw overwhelming support at the Town Hall meeting at the Solo National Championships this year for Stock. Stock will have one more year of competition, 2014, then get shut down for good, being replaced with Street.

The SEB's reasoning for making this proposal is that they believe that Stock competition had been waning, which it actually had been. What they fail to mention is that while Stock attendance had been dropping, they also added SEVERAL classes so folks had just been class jumping, not leaving the SCCA totally. Some folks have small attention spans and like variety. I'm not sure how you're going to gain attendance by shutting down a whole class set, but that, and many other questions of mine were never answered by the SEB in a real way.

Whats the big deal? It's hard to grasp if you dont dedicate as much time/money as a national competitor does. Solo is pretty much my life right now, having my class shut down and replaced with a version that makes my car considerably slower/less competent of a vehicle is not my idea of progress. I also have no inclination to lug my car around the country to drive it/compete on the same tires I drive to Target on.

You're free to make your own judgement on the whole ordeal, it's already said and done and I'm finished fighting that battle, we chalked up a big L and I'm now having to sell my A-Stock Corvette and buy a Super Stock Corvette.


Now, to address individual replies.

One of the thing that annoys me with tires (especially being an engineer) is that there's really no way to quantitatively compare tires, it is all qualitative. Almost every other component to a vehicle has something that it can somewhat quantify it's performance..

There is, we (national competitors) do an extensive amount of testing each year. The one thing good about running in stock is that most of that didn't apply to us, we already knew what was the fastest tire, the Hoosier A6. The folks in the street tire classes (STF/STS/STX/STR/STU), they know it boils down to a few tires (BFG Rival, Dunlop Z2, Hankook RS3, Toyo R1R), and will do testing throughout the year to figure out what is the magic compound/size for when early Sept comes around and we all head to Lincoln for the National Championships.

PM me your email address, I will send you the Traqmate comparison file and you can use the Traqmate software (free download) to parse whatever metrics you wish.

-The SEB (Solo Events Board) passed a proposal that would remove r-compound tires (tires below 140 treadwear) from stock competition and create a new class division called "street" which would be basically "Stock" only with 140+ (and 200+ in 2015 and beyond) treadwear tires.

Here's my issue with this - Treadwear numbers are, to my knowledge, only comparable WITHIN the brand. They're not cross-applicable or comparable ACROSS brands.

So, what's to stop an unscrupulous tire manufacturer from building a run of tires, with a comparative treadwear rating of 60 (super-sticky), throwing a 140 stamping on the sidewall, and making them "underground available" to a certain subset or "preferred group" of racers?

I mean, are they testing compound hardness with a gauge before each event? James, educate a brotha.

Because we all know which are the fastest tires, it would throw a MONSTROUS red flag if someone showed up with a tire that was unknown. A protest would be filed and they would most likely get DSQ'ed.

Cannot discern treadwear with a durometer. My A6's are 40 TW but a winter tire with 500+ TW is softer on a durometer. In grid, folks will walk around, look at each others cars and see what they're running. If something looks suspicious, someone will have to throw paper at the competitor (as solo is mostly a competitor governed sport, very rarely does scrutineering come into play) and prove that someone is cheating.

If a tire manufacturer created a 60TW tire that was "rcomp'ish", the results would tell the story themselves. If you have some nobody crushing the field by a second, something is fishy. While there is 1200 people at Nationals, we all know who the fast folks are and who the backmarkers are. We know who is supposed to beat who and by how much approximately.

I can't find the exact post, but the treadwear number basically just says how fast a tire wears compared to other ones. For instance, you would expect a 400 treadwear Michelin to last 4x longer than a 100 treadwear Michelin.

IN terms of polymers, durometer (hardness) is not the only thing that really means anything. You could make something very soft that is very wear resistant, where you could also make something very hard (relatively) that doesn't wear for crap. In the industry that I work in, we use a lot of rubber liners to line our equipment from abrasion (rocks). These liners "feel" about the same as a tire (maybe softer), but I can assure you they wear a LOT better than tires. Also, the durometer has little correlation to how it reacts to temperature (either low or high).

This is spot on. Softness and treadwear have no bearing on wear and performance. Like I said, a winter tire is softer than my A6, but will last longer and suck furiously if I tried to drive hard on it (probably wind up chunking). A Hoosier A6 and Hoosier R6 are both 40 TW, this number is very arbitrary, as the compounds are very different and perform differently (most r-comp level tires have arbitrary numbers).

Hankook's RS3 used to have a TW rating of 140, they have changed it to 200 starting this year. Tire companies can underrate a tire to make it seem "sportier".

If you stuck with this post, good for you!

[AZhitman]

GREAT info.

James, I enjoy your posts so much more than I did a year ago. Thanks for taking the time to educate the relative noobs... This makes sense.

[elwesso]

There is, we (national competitors) do an extensive amount of testing each year. The one thing good about running in stock is that most of that didn't apply to us, we already knew what was the fastest tire, the Hoosier A6. The folks in the street tire classes (STF/STS/STX/STR/STU), they know it boils down to a few tires (BFG Rival, Dunlop Z2, Hankook RS3, Toyo R1R), and will do testing throughout the year to figure out what is the magic compound/size for when early Sept comes around and we all head to Lincoln for the National Championships.

PM me your email address, I will send you the Traqmate comparison file and you can use the Traqmate software (free download) to parse whatever metrics you wish.

I guess when I made the comment that I did, I think it would be nice to have similar test results for all street tires, not just ones that people use for Auto-X. Basically the same idea that you're saying, but for "normal people" tires. Granted, the differences aren't going to be as big of a deal for a street tire, but it would make buying tires for the average person a lot easier to compare. It just bugs me that for street tires, all the information is all qualitative. Again, I really like TireRack's comparison guide, but I'd rather have quantifiable values to compare rather than a bunch of heresay by other people. On that note very few people report the tire over the life of the tire, most write a review probably less than half of the tire's life.

One of the things that I've never really understood with the SCCA classes is how they tend to change, and I can understand your frustration. If you specifically tune your vehicle to be as good as you can in a certain class, and then you have to either de-modify your vehicle OR add a bunch more modifications, that seems really counter productive. I would think this is something that has to be set in stone at least for a given amount of time.