When round and black becomes lean and green

[WriConsult]

Good point about tire break-in. I've found that a tire's behavior can change drastically after they break in -- usually for the worse, in the case of OEM tires. On several occasions I've bought new cars that cornered great when brand new but squealed in corners like stuck pigs after a few hundred miles. The offenders were Goodyear Invicta, Firestone FR480 and FR680. Made me wonder if the tires had an outer layer of "sticky" rubber to make them seem great on the test drive, but quickly wore down to cheaper rubber underneath.

Presumably this is less likely with the mostly non-OEM tires in this test. I haven't noticed the same phenomenon with any aftermarket tires I've bought, and there have been a lot of those.

[Damionk]

Originally Posted by xcel

Hi Damion:

___TireRack had to have a baseline to work from and what better baseline than all sets of tires being brand new and not yet scrubbed.

___In our experience, it takes a few thousand miles, not a few hundred before a tire is well broke in and scrubbed to the vehicle on which it was installed. With ever increasing miles, the RRc usually falls a small amount in concert.

___The GoodYear Integrity's braking distances in the wet were ~ equal regardless of pressure. They were only tested up to OEM MAX sidewall of 44 psi however.

___Good Luck

___Wayne

Yeah, I can understand needing a baseline. But, I think most here would agree that a "scrubbing" of around 1000 miles would be sufficient. I would imagine that the tires would be scrubbed at different rates due to different materials used in the tire making process. That I would think would give you differing RR during the break in process.

Thanks for the clarification on the Integrity's.

[bestmapman]

Great report. It is good to see CleanMPG getting involved with very useful reports like this.

[krousdb]

Wayne,
I have heard many times that the OEM Integrity (tires that were on the car when it left Japan) are different than the aftermarket Integritys that you can buy on Tire rack as replacements. The OEM tires are supposed to be LRR while the aftermarket tires are not. Can you confirm that what was tested were the original LRR tires, not aftermarket?

I am on my 4th set of Integritys. I made a point of buying them slightly used from dis-satisfied Prius owners.

[xcel]

Hi Dan:

___I will try and find that out for you...

___Another data point about the Integrity's... I know they are not so good in the wet and snow but the Corolla's Integrity's were replaced at 65,000 with another set of Integrity's and the second set is out over 110K now with another what appears to be 30,000 left to go. 50 - 70 psi has been the second sets life and the wear is dead even all the way across.

___Dan, you are running through them every 35 to 40K even with higher pressures on your Prius-II?

___Good Luck

___Wayne

[krousdb]

I run them well over the max sidewall. The wear is on the edges, with not so much wear in the middle. What you would expect from underinflation. Iv'e had two sets of integrity's, each gave me 45k miles. Then I had a set of Kumho's for 45k miles with lots of tread left but changed them for the Conti's hoping for better FE. But the Conti's were terrible and I went back to a third set of Integrity's, which lasted for 45k miles again. I'm now on the 4th set but seriously considering the Ecopia. That is why I asked about which Integrity was tested. If it was truly the OEM tire that was tested, I might have to order a set of Ecopias.

[CapriRacer]

First, Wayne, you are to be commended for the effort. This is about as good a tire comparison as I have seen.

2 points: I have been critical of Tire Rack's wet traction testing because it produces fairly high skid numbers - just like this one did. I think this is because of the depth of the water - not deep enough to get the tires to start hydroplaning.

Ordinarily, this would be a fault. But in this case, you want to be testing only the rubber compound - not the tread pattern - so the water depth is appropriate for the comparison that was done.

I have noticed that many tires for Japanese based car manufacturers have many poor wet traction complaints - something you don't get so much of for US and European based car manufacturers. I suspect this is because the Japanese based car manufacturers do their traction testing in Japan - even the tires from US and European based tire manufacturers. I further suspect the road surface they test on in Japan to be quite different than the road surfaces tested on in the US and in Europe. I am sure some of the inconsistency within the rankings for traction derive from this.

Background: Tread rubber compounding is such that the road surface itself can have a major influence on traction results. You can get reversals in rank order by testing on different road surfaces.

I strongly suspect the Goodyear Integrity used as a control suffers more from the Japanese connection than the advance in technolgy as speculated by Tire Rack.

For those who are unaware: Trying to compare tires that come on different vehicles is a lesson in futility - unless you know what each car manufacturer's specs are. On top of that, every vehicle platform will have a different spec.

So trying to base what the 185/65R15 Goodyear Integrity used on the Prius performs compared to what appears to be the same tire that comes on the Corolla - well, be very careful. These tires were designed indpendently of each other and they can be completely different.

And one last point: Tire wear wasn't measured in any way. This is quite understandable since tire wear testing - at least the kind that has meaning - is fairly expensive.

UTQG ratings are somewhat helpful, but the marketing department and the warranty department within each tire manufacturer battle of how to do them. The end result can be quite different between manufacturers. The only way to be sure what the wear is like for a given tire is to perform a test.

But overall a good and meaningful result - Congratulations!!

[ioverholt]

This is great!

I had noticed a surprising lack of tire talk on the forums. Rolling resistance has a huge effect on FE and so I figured there would be many discussions about tires. I guess everyone has not had their cars long enough to need tires.

I was going to start a thread on tires because I need new ones for my HCH-II before it gets wet. I have been intrigued by the new Yokohamas since I saw their claims about lower RRc and higher traction. After seeing the results, I am definitely going to buy the dB Super E-Specs. The tire improves on FE and handling relative to the stock tires. That is EXACTLY what I was looking for.

Although from the results it does not look like you could go wrong with the Michelin Energy Saver A/S or the Bridgestone Ecopia EP100.

Personally, I like to take turns at about the same speed as straights. I autocross an MK1 Scirocco for fun, so I know a thing or two about turning. I'm just not impressed by drivers who drive fast in a straight line, but almost stop when there is a turn (most SUV drivers). If you can't make a turn at your straight-line speed, then you really don't have any safety margin.

Thanks for the great article!

[PaleMelanesian]

There wasn't much talk because there was almost zero data until now. It's pointless to speculate when you have nothing concrete to discuss. We know very well how much tires affect *everything*, and now we have some data to discuss.

[warthog1984]

Originally Posted by ioverholt

Personally, I like to take turns at about the same speed as straights. I autocross an MK1 Scirocco for fun, so I know a thing or two about turning. I'm just not impressed by drivers who drive fast in a straight line, but almost stop when there is a turn (most SUV drivers). If you can't make a turn at your straight-line speed, then you really don't have any safety margin.

If you make a turn at straight-line speeds, you're gonna bend something.

Oh, you meant the OTHER Autocross

We don't need no stinkin' parking lot