argonaut

I have a set of Hankook C51, 275/5/18 square. This is their medium compound road racing tire. The tires have no tread, just two circumferencial grooves. And yet the tires are directional, an arrow on the sidewall clearly points out direction of rotation.

In the past I've always been told the only reason modern radials are directional is due to tread pattern. But these tires have no tread, so why are they directional?

If its for reasons of performance then I wouldn't worry about running them backwards, but if its a safety issue then of course I'd be concerned. The Hankook website says nothing on the matter.

Thoughts?

PS: this tire is absolutely awesome. Fantastic grip, wear well and never get greasy - and cheaper than Hoosiers to boot. Love the tire, but if I can run them backwards with no safety concerns then I'd love them even more.

c4cruiser

If you're wanting to rotate them due to wear, then you should be able to have the tires dismounted and moved to the other side of the car. As long as the directional arrows are pointed in the same direction, the "old" outside edge of the left tire will be on the inside edge of the right side tire. Extra work for a tire shop, but it does keep the tires rolling in the right direction.

Nowanker

I don't have specific experience with the Hankooks, but when Kumho Victoracers were new they had an issue with the tread peeling off. Followed REALLY soon by instructions about the direction of rotation. Contact Hankook?

ZedO6

My experience....the manufacturer will not ever tell you to run a tire opposite of the sidewall markings. I've done it on directional R comps (not on Hankook's) and had zero issues. Many others here do it as well with no problems.

With that said, the carcass plys are directional and will tighten under braking or loosen, depending on direction. Not sure how big a factor this is on your tires but I used to work for a tire manufacturer and this was clearly communicated to us with regard to direction.

froggy47

Interesting about the plys. Had not heard that.

I have run every tire I ever had on my Corvettes tread or not in both directions, no issues.

When Kumho had the separation issue they specifically said to reverse the direction to help with the problem. They did not have direction arrows, however.

If some have arrows and some don't, are the carcass plys wrapped "better" on the ones that do not have arrows? Does not make sense to me.

Bill Dearborn

I would rotate my Kumhos from side to side from one event to the next. That helped reduce the separation. I only saw it happen when I was autocrossing. Track events didn't seem to bother the tread splice as much although I did flip from side to side and front to rear to equalize wear.

As for a slick being directional it must have something to do with the tire's construction. They may be using some sort of construction that lowers rolling resistance in a specific direction. Reversing direction might cause more heat build up in the tire but that is a pure SWAG.

Bill

hklvette

Actually, there may be some truth to that. Formula 1 found out the hard way last year what happens when you run a "directional" carcass backwards. If you're not familiar with the associated incidents, look up "2013 Silverstone Grand Prix tires" That should get you close.

Bad Karma

That's exactly what I was about to say. Prior to last for ears tow issues I would have flipped them backwards thinking only about tread pattern, after that though, I'll stick to the intended direction, just in case...

RDnomorecobra

from tirerack ... Ventus Z214 tires feature directional rotation arrows branded onto their sidewalls to identify correct mounting rotation that will enhance tread splice integrity and durability. Following the rotation arrows, the use of a symmetric tread design allows Ventus Z214 tires to be mounted on either side of the car (and later be remounted inside out to further extend their life).

Hi Volts Z06

I always thought there was concern of belt shift when reversing a radial that had already been run in a certain direction. I would think this is even more important for a race tire that sees extreme loading.

argonaut

Well - better safe than sorry so I'm not going to try reversing them. Kind of sucks - many tracks are harder on left side tires (clockwise tracks). It's nice to rotate side to side at the end of each day. I do it with the Continental Hoosiers but alas not with the Hankooks...dang.

ZedO6

As suggested earlier in this thread, I don't see why you can't have the tires from the left and right sides flipped on the rims and run them on the other sides? Of course that's gonna cost you something but it's better than going through half a set of tires quickly. Good luck

redtopz

What this is saying is initially the tires should be mounted in the direction of the arrows so that the tire splice has a chance to heat up and fully bond. After one or two good heat cycles it would be fine to swap directions as the splice will not separate. They just don't want you going out on a new tire and separating the splice with hard braking or acceleration. One time I raced on goodyear dot tires at Cal Speedway and the tire split in half where it was spliced. I called goodyear and they said the tires are directional even though they provided no arrows or instructions . After the initial heat cycle they said you could run them any direction. They also corded in one session. I've been on hoosiers ever since. Although I raced on the Hankook team at the 25 hours of T-hill and they are awesome tires too with the same grip at the end of a 2 hour stint as the start.

0philstireservice

Usually if a tread splice opens up, you can run the tire in the other direction and it may close up.


BTW Hanook z214's are NOT a slick they are a DOT R comp tire.