Tire discussion with a Falken engineer

[AZhitman]

Here's a transcript of some recent email correspondence with an engineer from Falken Tire. Enjoy!

ME: In looking at your website, it appears the load rating for the Ziex-ZE-512 in the 255/50/16 size may be incorrect, at 1201 lbs.

I have recently purchased a set of these for use on a car requiring tires with a static load rating of 1400 lbs+, so it's very important that I confirm that this is indeed an error.

Also, the max inflation pressure is listed at 50 psi - Why is this different than what is printed on the sidewall?

Thanks for your prompt response.

FALKEN: The Falken ZE-512, size 255/50R16 carries a max. load of 1,709 lbs. (775kg.). It's max. inflation is 51 p.s.i. Our factory sometimes make subtle changes to the specifications, and it take a while to update our printed material and website.

ME: Thanks Tim. My sidewall indicates a different max inflation - is this intentional? What is the max load rating for this tire at 35 and 42 psi? Keep in mind I am in AZ, and at 120 degrees ambient at 100 mph, with a 4200-lb car, there are enormous variances in pressure (which I monitor weekly).

FALKEN: With our 255/50R16 size tire, it will support 1653lbs. at 35 psi. The max load the tire will support is 1709lbs. at 36 psi. The higher allowable setting's (51 psi max.) are for higher speeds (above 100) to help keep the casing from distorting and flexing. Flexing also causes higher temperatures in the tire, so I would recommend 3~5 psi additional (than 36, or the recommend vehicle setting) to help reduce casing flexing and help reduce higher temps in the tire in the Arizona climate. Tim Widener - Product Engineer @ Falken Tire

[Q45tech]

The amount the tire will support is a wishy washy answer. At least he covered himself [maybe] with the 3-5 psi increment added to cold 36 psi.........Support for how long?

Tire engineers don't know the following without testing tires on the specific vehicle. Recently many have purchased half million dollar machines which can simulate inputed parameters so they don't send a manufacture a tire for consideration that will fail immediately.

The question is for how many minutes and seconds at 'x' vetical load with 'y' camber and 'z' toe scrub will the tire not fail on a asphalt road of 'W' friction coefficient at an ambient of 100, 110, 120F. Then you test at speed increments until failure and then you can report that a tire is satisfactory for use on one vehicle.

This is what the car manufacturers do because they have to!

Remember all tires are lab tested with ZERO CAMBER, do you have zero camber? Does yout tread temperature exceed 100F if so the specs are meaning less!

What one needs is an embedded tire tread temperature sensor along with pressure sensor.

Anyway we know that 1521 [95V] was the factory choice so 98V of even the worst brand should be good enough to meet what the 95V Michelins did? Right?

The other problem is there are NO ENDURANCE TESTS for aged tires.........when do the tires begin to lose capacity from street wear is it at 8,000 miles, 10,000 miles or 15,000 miles.Michelin says in their report to the government that they think 20,000 miles is the limit and car manufacturers agree by spec tires that tend to wear out by then {{on performance cars}} - to get away from the liability as fast as they can run!

[Grant@tirerack]

"What one needs is an embedded tire tread temperature sensor along with pressure sensor. "

That is on the way. For the life of me I can't remember which of the major brands was working on that system but it is in R/D. We saw a blurb on that a few months back and I want to say it's Goodyear.

[Grant@tirerack]

Found it:

http://www.rfidjournal.com/article/view/93/1/1/It's not the exact article but it was Phillips and one of the major tire makers working on the project. The newer article was about ongoing field tests.

[AZhitman]

Anyway we know that 1521 [95V] was the factory choice so 98V of even the worst brand should be good enough to meet what the 95V Michelins did? Right?

That's why I'm glad I have the 99V tires for some margin... AND I'll experiment with some different pressures. Right now I'm at 35psi, I'll switch all four to 40psi for a week and see how I like it.

If I can find my IR thermometer, I'll take some tread readings after a 100mph blast in 120 degree ambient on an "average" freeway and post the results.

Dammit Dennis, see what you're turning me into?

[Q45tech]

I keep my IR in the car and you will be surprised at the straight ahead temperatures! Most Z/Y summer street tires like 180F max. Most A/S die at 140F...............can you imagine the Fstone [S rated A/S failed versions] in Venezuela 95F at 99 mph for hours............obviously the worst case will be the inside edge.

I have seen 167F after 2 hours in 95F at 85 mph with my -1.1 front camber and that was on Michelins.

People make a terrible mistake by buying new tires in the Summer before going on vacation........they destroy them [for winter use] in the heat because the tread is new and full depth!

[Grant@tirerack]

It sounds like you guys would love the Smartire system we have in the wife's van. We can look at the real time psi and temp for each wheel/tire on the fly! My wife was amazed how much the temp and pressure changes in various conditions. It measures internal temp in the air chamber.

[AZhitman]

I have seen 167F after 2 hours in 95F at 85 mph with my -1.1 front camber and that was on Michelins.

I'll bet I can beat that: Ambient air temp of 120, vacillating between 100-120mph for 20 minutes on my monthly blasts over to Scottsdale Infiniti (I-10 is poorly enforced by DPS)... Wonder what kind of tread temps I'm generating?

Dennis, what brand of IR do you have, and what brand would you recommend for replacing mine (I can't find the damn thing and I won't spend more than $80).

Grant, tell us more about the SmarTire system.

[Grant@tirerack]

Hop on over to the APC Tire Monitor thread! The water's fine!

[szh]

Just a few days ago, I was driving to work with my son - ahead of me was an SUV with a badly deflated rear tire. We came to a stop next to each other and I motioned to the driver about his rear tire (the usual waving arms to get his attention and squeezing the fingers to tell him about the tire deflation).

The driver nodded at me like he understood and smiled. So I assumed that he got the message. Yet, a couple of hundred yards later, he entered the highway onto 101 South!

I can only hope that "survival of the fittest" rules removed him from the gene pool that day - I just wish I had not seen his kid in his back seat!

Z

[Nismo_Freak]

I'll bet I can beat that: Ambient air temp of 120, vacillating between 100-120mph for 20 minutes on my monthly blasts over to Scottsdale Infiniti (I-10 is poorly enforced by DPS)... Wonder what kind of tread temps I'm generating?

Dennis, what brand of IR do you have, and what brand would you recommend for replacing mine (I can't find the damn thing and I won't spend more than $80).

Grant, tell us more about the SmarTire system.

Try hitting up Lime Creek Road when it's 109 degrees outside with 2 degrees of camber front to rear. That road will test every last bit of your ability to drive a fatigued car. The suspension gets softer, brakes are nuked, and the tires are hot as hell. Auto-X doesn't have crap on this road. It's like a 5 mile long auto-x roadcourse mixed with an alpine hill climb.

Did I mention that my car would not accelerate above 80 mph in the last straightaway that's about 1 mile long ... not that I push the car any :icesangel