New Tire Rack Tests

[CapriRacer]

A word of caution:

Tire Rack's wet traction testing has always yielded high values. I suspect this is because they do not use enough water depth.

Wet traction values can range all the way down to 10% of the dry traction values depending on the road surface, the water depth and the vehicle speed, but typically it's more like 50-60%. To see G values higher than that makes me think folks need to take Tire Rack's wet traction figures with a grain of salt.

 

[Sayjac]

Not here to dipute or confirm TR's rain results of the Yoko Avids. Just to say, had a set of Avid Touring's (before they added the 'S") on an 01 Civic. They were a great wearing tire (~70k), and decent riding tire. Seemed to be ok in the rain.

Replaced them the Gen HP's because of a great promo price at the time. Don't think I'll get 70k, closer to the rated 55k, but they do seem excellent in the rain, even heavy rain.

 

[George Bynum]

Originally Posted By: CapriRacer
I suspect this is because they do not use enough water depth.
Some time when you have nothing better to do , take a ride to Greer SC ... the BMW Performance Center ... when they are doing a class. It's AMAZING to watch from public areas at what just a little water(?) does with polished concrete ... I'd like to take that basic course, but haven't. It's not terribly expensive.

 

[rpn453]

Originally Posted By: CapriRacer
To see G values higher than that makes me think folks need to take Tire Rack's wet traction figures with a grain of salt.


The results certainly are much higher than that of the UTQG standard. I always figured the UTQG tests were performed on an unusually slippery or wet surface, but maybe it's the opposite and TireRack's test track is unusually grippy or dry. Either way, as long as TireRack is using a consistent procedure, location, and moisture level, the test results should be comparable. Even if the conditions are inconsistent from test to test, the results would still be useful for comparing tires within a specific test group, though I suppose the surface they use may favor certain tires. I'm just glad somebody's performing and publishing some comparison tests.

 

[CapriRacer]

Originally Posted By: rpn453
...... Either way, as long as TireRack is using a consistent procedure, location, and moisture level, the test results should be comparable.........


My issue is that it appears that Tire Rack's test down-plays the role hydroplaning takes in wet traction. Some tires will appear to have great wet traction values, but as soon as the water depth is increased, the tires start to hydroplane and all that grip dissappears.

 

[SteveSRT8]

X2. I am cautious when reviewing anything online.

I haven't noticed an 'agenda' in TR's published stats, but they are probably not the best source, just more input.

 

[mjoekingz28]

Maybe the tire rack can start testing the fuel efficiency of their tires. I had some 9 year old Kumho 732 touring pluses and got 40 mpg and on this hill I crest every day I always throw it in neutral and coast. ON the 732 I would consistently hit 51mpg. With my new KR22s, I get 38mpg and only hit 48mph on the same hill.

These are immediate results. Noone believes that tires make a difference, but I just say on Tuesday I was getting 40-41mpg and the following day (Wednesday) I was getting 38mpg and has been consitant ever since. Sad thing is, these 22s are Low Rolling Resistance tires, but don't act like it.

I cant really blame the Kr22 though, as I had Tiger Paws before them and got 1 . lower (37mpg).

 

[Hokiefyd]

Originally Posted By: CapriRacer
My issue is that it appears that Tire Rack's test down-plays the role hydroplaning takes in wet traction. Some tires will appear to have great wet traction values, but as soon as the water depth is increased, the tires start to hydroplane and all that grip dissappears.


Capri, aren't these two metrics (wet traction and hydroplaning) two completely separate ones? In other words, they would be measured differently, and would also likely be encountered in different situations on the road. I don't think Tire Rack is attempting to measure a tire's resistance to hydroplane...they're measuring the lateral grip a tire can generate on a wet surface. I agree with you that once a tire hydroplanes, all that grip is gone, but since most driving on a wet road is NOT in water depth that would cause hydroplaning, I think Tire Rack's wet traction testing has merit.

If you are suggesting that Tire Rack could ADD an additional test that would measure a tire's resistance to hydroplaning, I would agree that the results would be useful.

 

[CapriRacer]

Originally Posted By: mjoekingz28
Maybe the tire rack can start testing the fuel efficiency of their tires. I had some 9 year old Kumho 732 touring pluses and got 40 mpg and on this hill I crest every day I always throw it in neutral and coast. ON the 732 I would consistently hit 51mpg. With my new KR22s, I get 38mpg and only hit 48mph on the same hill.

These are immediate results. Noone believes that tires make a difference, but I just say on Tuesday I was getting 40-41mpg and the following day (Wednesday) I was getting 38mpg and has been consitant ever since. Sad thing is, these 22s are Low Rolling Resistance tires, but don't act like it.

I cant really blame the Kr22 though, as I had Tiger Paws before them and got 1 . lower (37mpg).



On all the tests posted, TR did! I hope you are not suggesting they test EVERY tire they sell.

But your results? Did you take into account that worn out tires get better fuel economy than new, unworn tires - all other things being equal?

 

[CapriRacer]

Originally Posted By: Hokiefyd
Capri, aren't these two metrics (wet traction and hydroplaning) two completely separate ones? In other words, they would be measured differently, and would also likely be encountered in different situations on the road. I don't think Tire Rack is attempting to measure a tire's resistance to hydroplane...they're measuring the lateral grip a tire can generate on a wet surface. I agree with you that once a tire hydroplanes, all that grip is gone, but since most driving on a wet road is NOT in water depth that would cause hydroplaning, I think Tire Rack's wet traction testing has merit.

If you are suggesting that Tire Rack could ADD an additional test that would measure a tire's resistance to hydroplaning, I would agree that the results would be useful.


Actually, my issue is that it's more complex than people give it credit for. Even within BITOG, there is a lot of confusion. Plus the affects of hydroplaning start to be felt as low as 45 mph. I just think their speeds are too high not to have a more pronounced affect - hence my objection.

 

[IndyIan]

Originally Posted By: CapriRacer
Originally Posted By: Hokiefyd
Capri, aren't these two metrics (wet traction and hydroplaning) two completely separate ones? In other words, they would be measured differently, and would also likely be encountered in different situations on the road. I don't think Tire Rack is attempting to measure a tire's resistance to hydroplane...they're measuring the lateral grip a tire can generate on a wet surface. I agree with you that once a tire hydroplanes, all that grip is gone, but since most driving on a wet road is NOT in water depth that would cause hydroplaning, I think Tire Rack's wet traction testing has merit.

If you are suggesting that Tire Rack could ADD an additional test that would measure a tire's resistance to hydroplaning, I would agree that the results would be useful.

Actually, my issue is that it's more complex than people give it credit for. Even within BITOG, there is a lot of confusion. Plus the affects of hydroplaning start to be felt as low as 45 mph. I just think their speeds are too high not to have a more pronounced affect - hence my objection.

You're saying that a tire pushing alot of water out of its contact patch will have less traction well before it aqua planes? Whereas the tirerack is just basing wet traction based on a wet road with a small amount of water that no tire seems to have trouble clearing with no reduction in wet traction.

 

[rpn453]

Originally Posted By: CapriRacer
Actually, my issue is that it's more complex than people give it credit for. Even within BITOG, there is a lot of confusion. Plus the affects of hydroplaning start to be felt as low as 45 mph. I just think their speeds are too high not to have a more pronounced affect - hence my objection.


Do you think they're cheating somehow?

I don't think hydroplaning is much of a factor at 45 mph with a decent tire, though I have driven on other tires that hydroplane quite easily. F1 cars still go amazingly fast on their full wet tires over standing water, and in light rain the intermediates are plenty. 200 mph doesn't seem like a problem for them. Both tires get them surprisingly close to a dry pace, considering the conditions. Sure, they have a lot of downforce, but the tires are also extremely wide for a 1200 lb car. They may use better compounds than on a passenger tire, but the full wet tread design is basically that of a high performance all-season tire, while the intermediates are like a high performance summer tire.

 

[Hokiefyd]

Originally Posted By: IndyIan
You're saying that a tire pushing alot of water out of its contact patch will have less traction well before it aqua planes? Whereas the tirerack is just basing wet traction based on a wet road with a small amount of water that no tire seems to have trouble clearing with no reduction in wet traction.


Your first question is an excellent one, and goes to my point better than I did. I just assumed/thought that hydroplaning was a binary condition. You either "are" or you "aren't" hydroplaning. If somebody is suggesting that water depth will influence the level of a tire's wet traction, given that hydroplaning is NOT occuring, then the issue is surely more complex than I gave it credit for.

 

[rpn453]

Cool, rainy day today, and I was doing some thinking while driving (uh oh). I tend to frequently break traction in my front tires coming out of corners and off/on-ramp curves or while accelerating into traffic from a stop, often multiple times during a single drive through the city. First gear is short, and I have an open diff, so it's very easy to get a tire to break if I have the steering wheel turned at all while applying throttle. I enjoy being on the edge of traction so I tend to just feather the throttle while the car catches up. Obviously I have to tone it down a bit in the wet, but not by much, and I don't change my cornering speed; I still try to limit off/on-ramps to double the posted limit, just like when it's dry.

So I went out and did some hard slaloming with imaginary cones on the centerline of an empty section of twinned highway with good shoulders at the posted speed limit of 110 km/hr (70 mph). After getting comfortable with taking a vehicle to its dry limits at Bondurant last spring, it's something I've done with a few vehicles to get a feel for them, but I hadn't done it in the wet before. The rain was light and there was no standing water. The limits still seemed to be very high, with minimal understeer at the limit. It really doesn't seem like I'm losing that much traction in wet conditions. I do remember having less wet traction with the Goodyear RS-A OE tires. That was immediately obvious, and I was glad to be rid of those tires. Since then, I've been progressively using my Pilots later in the fall and earlier in the spring and it has made me realize that my winter tires (studded Cooper Weathermasters) may also be poor in the wet. It just isn't as obvious because I avoid breaking traction with them in order to preserve the studs.

I dug up an interesting Car and Driver test that I've posted here before, where Goodyear summer, all-season, and winter tires were all tested together in dry, wet, and snowy conditions. Dry and wet grip levels are both about .10g lower than that of typical TireRack tests, but the change in traction from dry to wet is similar to that of the better tires in TireRack tests.

C&D - A Tire For All Seasons?

 

[IndyIan]

Originally Posted By: Hokiefyd
Originally Posted By: IndyIan
You're saying that a tire pushing alot of water out of its contact patch will have less traction well before it aqua planes? Whereas the tirerack is just basing wet traction based on a wet road with a small amount of water that no tire seems to have trouble clearing with no reduction in wet traction.


Your first question is an excellent one, and goes to my point better than I did. I just assumed/thought that hydroplaning was a binary condition. You either "are" or you "aren't" hydroplaning. If somebody is suggesting that water depth will influence the level of a tire's wet traction, given that hydroplaning is NOT occuring, then the issue is surely more complex than I gave it credit for.

I'm pretty sure that's what capriracer was getting at, as the speed or water depth increases the water pressure created under the contact patch is gradually increasing to the final point where the tire totally loses contact.
I'm sure the water pressure doesn't increase linearly either so in 1/2" of water 50 mph may still give you 75% of wet traction but 70 mph has your front tires barely contacting the road.

 

[CapriRacer]

Perhaps this will help clear this up.

I am sure everyone is well aware of the advice to put new tires on the rear. Every year for the past 5 years, the company I work for has put on a demonstration.

They set up 3 cars - 1) all new tires, 2) new tires on the back, worn tires on the front 3) new tires on the front, worn tires on the back. The worn tires had been shaved to 4/32nds of an inch. The tires were standard all season tires - ones discussed here at BITOG!

Then we had folks drive around a large skid pad at between 45 and 50 mph where one section had some water running across it. The water depth is very thin - about 1/8". You could walk through the water - albeit very carefully - and only the soles of your shoes would be wet - the sides would not.

Here's what happened:

Car #1 - didn't notice the water was there.

Car #2 - the front end hydroplaned, but once you left the water, you were pointed in the right direction and could regain conrol.

Car #3 - The rear end hydroplaned and spun around - there was no warning and there was no driving out of it.

We let 100's of people drive the 3 cars and the results were always the same.

What you should take out of this is that it doesn't take much water or a very high speed to get a worn tire to break traction. That would be less true for new tires. but now we are discussing water depth and speed.

In fact, sometimes there was trouble getting Car #3 to spin - or put more precisely, the speed where this would happen would climb to the point where the driver felt like he was going pretty fast around the circle - sometimes as high as 55 mph! What was ideal was if the driver felt only slightly stressed, but comfortable, at the cornering speed. The water depth - or more precisely, the amount of water being pumped to the water outlets - was adjusted accordingly.

Ocassionally the water flow would have to be decreased as the amount of recovery room was limited and the car would get thrown out of the circle at an angle that shortened the recovery distance.

They've done did this with both FWD and RWD, but FWD's are available in shorter wheelbases, so the spin is more dramatic. Plus the heavier RWD just seemed a bit more dangerous - and they really didn't want anyone to get hurt.

What I took away from this was that the tire was partially hydroplaning, and applying a certain cornering load was enough to overcome the available traction. What I found interesting was that the speeds being used were less than what Tire Rack was obtaining - leaving me to believe that they are not using enough water.

 

[rpn453]

Originally Posted By: CapriRacer
What I took away from this was that the tire was partially hydroplaning, and applying a certain cornering load was enough to overcome the available traction. What I found interesting was that the speeds being used were less than what Tire Rack was obtaining - leaving me to believe that they are not using enough water.


Yeah, I suppose the speeds Tire Rack uses are too low and the surface probably doesn't have much standing water. The testing may be incomplete, but the information is still relevant to me considering that our roads are very rarely covered in standing water. 1/8" would be a lot of water if it were covering the entire road and not just puddles in the road grooves. I can only recall driving on water like that once in my life - during a heavy downpour - and I had to slow down to 60 mph for visibility reasons rather than traction or hydroplane concerns. But I've also driven on tires that would have been dangerous at 70 mph in that situation, like the brand new Dunlop SP Sport Maxx GT tires on my buddy's S4. I don't think those tires should be used in rain. Even if I wanted summer tires, I would have posted those tires for sale on Kijiji immediately after the experience of driving with them in the rain. Really, I would have sold them before that though, because consistent summer conditions are only available for three months a year here, and even then there's a lot of gravel left on the road.

It would be nice if Tire Rack tested in two different wet traction situations. They could do one on wet pavement with no standing water to determine how good the rubber compound grips a wet road, and another with standing water to determine the hydroplane resistance of the tread design. They should be taking the car to at least 80 mph in both situations. That would provide a lot more information and really expose the tires that are inappropriate for wet conditions. All they give us is the wet traction absent of any hydroplane effects.

 

[FZ1]

Originally Posted By: mjoekingz28
Maybe the tire rack can start testing the fuel efficiency of their tires. I had some 9 year old Kumho 732 touring pluses and got 40 mpg and on this hill I crest every day I always throw it in neutral and coast. ON the 732 I would consistently hit 51mpg. With my new KR22s, I get 38mpg and only hit 48mph on the same hill.

These are immediate results. Noone believes that tires make a difference, but I just say on Tuesday I was getting 40-41mpg and the following day (Wednesday) I was getting 38mpg and has been consitant ever since. Sad thing is, these 22s are Low Rolling Resistance tires, but don't act like it.

I cant really blame the Kr22 though, as I had Tiger Paws before them and got 1 . lower (37mpg).
They do test for mpg. It's right in the test at hand. Surprise! Surprise! The Comfort Tread Tourings got better mpg than the Michelins.

 

[ponderosaTX]

Quote:
I am sure everyone is well aware of the advice to put new tires on the rear. Every year for the past 5 years, the company I work for has put on a demonstration.

The problem with this advice is that it is short-sighted. Front tires wear more rapidly than rear tires, particularly in FWD cars. What happens when it comes time to rotate the tires front to back (which is the only rotation allowed for unidirectional tires)? The differential between front and rear tread depth is worse than the original configuration where the "engineers" recommended putting the new tires on the back.

Costco insists on this silly policy so I sent an online inquiry to the Michelin technical experts repeating the argument made above: putting the new tires on the back creates a worse imbalance after rotation than putting the new tires on the front would have created in the first place. The Michelin experts never replied, presumably because the logic is irrefutable.

 

[rshunter]

There are auto manufacturers and tire suppliers who advise against routine tire rotation. In such cases a new pair of tires would always go on the rear, with the older pair being placed on the front. Barring the use of different tire sizes between the front and rear axles, that is.