wolfdogs

Some of you know, I was a tire engineer with the U.S. Govt. prior to my retirement. I ran the Federal Tire Qualification Program for 13 years, and worked side by side with the NHTSA manager of UTQG..comparing numbers and data.... (this just for clarification...not "patting myself on the back")

Anyway, when I retired, the Govt. let a few of my instruments go with me.. one, a Shore A durometer.. http://en.wikipedia.org/wiki/Shore_durometer

This is mine, not cheap mind you...Uncle Sam paid for it though (I know..your tax dollar at work.. )



This particular model measures rubber hardness of tires...which.. as a tester, we can tell a lot during a tire test with whats going on, not only inside the tire with mileage, but also the compound itself.. by measuring the hardness every 4k miles over a 20k tire test at 100% load.

Even though I only have 3900 miles on my 08 C6 Coupe... I have noticed that these tires tend to spin pretty easy.....granted we have lots of power, but having muscle cars since 67...some with more power than this, I started wondering about these tires. I also was able to break them loose slightly in a tight cornering situation a couple of times... which surprised me.

So tonight, I dug out my ol trust worth buddy, and heres what I found, at only 3900 miles:

Shot 1. the Crown edge of the right front..... normal hardness for passenger car tires is around 68-70, but on speed rated high performance tires, the crown edge compound is usually softer than the center crown compound to provide grip in corners... drawback: the more you play, the fast the tire wears out but on the crown edge of the tread first. We should have seen a 60 here.....

(sorry for the blur...most of the next few pics are better)

We got a 70... thats a hard compound out there..



now, keep in mind, the more miles you put on the tire, and the hotter the tire gets, the more hardness sets in on the compound... at 15k..these tires will most likely be around 75-78... and for performance driving, thats like driving on owl ****.........(no offense Goodyear)...

So..I took the next reading at the center rib of of the same tire:



have we no difference in compound hardness? did they use the same compound for the whole tread surface?

next.. the 2nd block rib in



then the right rear tire, keeping in mind, i have done very little spinning of these tires on takeoff..... if I had.. this compound would be like cement at 10k.... it's a little better than the fronts, the crown edge is softer, but not soft enough in my book..and the center rib is softer than the front tires, but only by a few marks...



poor launch traction, folks... poor...



Now, Im not bashing GM or Goodyear, but lets face it, these tires were designed to give the owner of a new Vette the best mileage possible and to give them the input on cornering and launches to "slow it up..you are spinning/sliding"........

When I replace my tires after..........who knows... IM going with a true performance tire that will let this car do what it's designed to do with a driver that knows how to make it happen.

Just and fyi. Thought yall might be interested..

keyplyr

That's what I did. I hated those runflats!

spin-doktor

I knew Goodyear Eagle tires really sucked all along. This is just further proof. My stock set of supercars lasted 15K miles (replaced with INVOs) They were grippy when new, near new, but as soon as they start getting worn down a bit, they suck like no other tire.

Poor, poor traction ! and dont even get me started with "driving in the rain" *sigh* GY = FAIL.

evilz

Wolfdog,
Good to see you are relaxing now that your retired. I've got 45k on mine. I picked it up with a new set of the run craps. All I can say is that I've lost traction more than once with these. At freeway speeds+++, it can get a little interesting, real fast.
Thanks for the post.

Walt White Coupe

Thanks for the informative post. I'm curious about what numbers you'd get from a Z51 Supercar tire for comparison. Since you said you're going for a "true performance tire" when it's time to replace them, I guess you're talking about a non-runflat. Would be interested in what tire you determine fits that bill.

Lots of people like the Nitto Invo's but I don't like that fact that I'd have to drop down in tire aspect ratio and therefore tire diameter with them.

evilz

K9KUZ

Keep us posted on this.

NYC6

Imteresting...Very Interesting.

wolfdogs

I'll damn sure let yall know..but its going to be a while at this rate unless I come into to play money now that Im a retired worthless bum..LOL.. but.. if you dont play hard, you should get quite a few miles out of this compound type tire..... the trade off is: traction = low treadwear always has been... I might must take a day and go up to some tires stores with my ShoreA and "browse around"... might be fun.... I know the BFG G force tires are excellent when it comes to proper compound placement on the tread surface.. right now, that would be my choice.

wolfdogs

ps. anyone local in N.Va. (or anywhere for that matter) is welcome to drop by and we'll run across your tires with the Shore A to find out whats happening. Just pm me.

Shark Racer

Doesn't rubber harden with age? I would assume this effect to occur more quickly on a harder rubber.

BTW, Nitto Invos have a lower overall limit of grip and sloppier handling than the stock GYF1SCs on my 07Z.

C&D ran an article - Invos were crappy in dry weather. Great in wet though, as I expected...

danl72

Thanks for the info. Very informative.

inthehunt2

WD - Keep us up to date please.

jpuli28

BFG Tire Site... http://www.bfgoodrichtires.com/overv...-a-kdw/22.html

Your vehicle: 2007 Chevrolet Corvette Standard
Original Equipment Front: P245/40ZR18/LL
Original Equipment Rear: P285/35ZR19/LL

We are unable to find an exact fitment for your vehicle. Thank you for your interest in BFGoodrich® tires.
Unfortunately, there are no BFGoodrich® tires that match your vehicle description.

wolfdogs

yes, rubber does harden with age.

most rain worthy tires use a harder compound, to channel water better, but grip is gained by siping and proper placement of traction grooves and design of the tread to channel the water, for the harder compound by itself does not add to wet traction....

there are new compounds coming out all the time, the tire manufactures have discovered a way to make a compound change with ambient temps...... they do it for winter tires. Its not new though, Goodyear did it first years ago..with the F32... the compound softened with lower ambient s, ....law enforcement that operated in the mountains on snow and ice loved it.. Goodyear dropped it..back in the early 90's... they have newer offererings now, as does Michelin and several others..

markabc6

Thanks for the FYI...
No way am I disputing your qualifications or findings, but respectfully we need more empirical data from a larger share of Vette owner demographics.

IMOHO... a "good*" tire doesn't last long anyway, before it starts getting hard and loosing traction...so forget about mileage, let your butt tell you when you need new ones.

* Good doesn't necessarily mean the stock tires

designerRob

Thanks for the info. I was also really surprised how easy my rear tires would break loose accelerating around a corner.

wolfdogs

I have not bothered to surf to see if they made a size for the vette. I had them on my 97 Comp TA and our 97 Firehawk and was going to put them on my 05 GTO but sold the car before it happened. Was very pleased with the overall performance to the tires, wet traction was a little less but thats to be expected.

wolfdogs

very true.

Ive been in quite a few rodeo's with this subject.... and in the drivers seat as well....LOL O.E. is always a compromise...it's aimed at the general public...... not the hard core enthusiast.

69L79

So, you are saying that Goodyear tires basically suck? I think we can all agree on that. Michelin?