Are the dry tyres directional now?

[ISLAMATRON]

so you always have to buy run flats? those are not even the best type of performance tires and only a couple companies make that type of technology. (BS & goodyear?)

[RacingManiac]

which is why their "M" cars don't use run flat....I think Corvette Z06 and such even comes with tire-sealant foam....because spare would be heavy and useless and runflats are a compromise...

Interestingly though, the standard tires on the new Nissan GTR, both the Bridgestone and Dunlop are runflats....and are a key part of that car's speed...I'd venture to say those are probably the first of its kind, the "high performance run-flat"...

[Jersey Tom]

ZR1 is on runflats I believe.

[F1ParkingSpace]

Spare? BMW provides no spare because of the run-flats! I am not yet sold on this concept, but I bought in to the idea. Hum..............?

That reminds me, I need to check the spare on my car...thanks!!

And just to add that the Bridgestones on my Fiesta have a directional tread and the tread is different from one side of the tyre to the other, so I assume you couldn't swap tyres from left to right and vice-versa.

[F1_eng]

F1 tyres certainly are rotational, this is due to the different loading conditions seen by the tyre in various direction. For example the behaviour and needs of the tyre in longitudinal acceleration and decceleration are completely different.

On a road car tyre, the directionality is purely down to the way water is cleared. The aim is to squeeze the water away from the centre of the tread area outwards, you can imagine if the tyre is wrongly installed that water could actually be squeezed inwards.

As for the problem encountered by someone, I can't see any way which the directionality of the tyre caused this.

It is also interesting to note that MotoGP use different compounds on the same tyre, this is if the track is biased in either corner direction.

[Fil]

...MotoGP use different compounds on the same tyre, this is if the track is biased in either corner direction.

MotoGP stopped using asymmetric tyres in 2009 under the cost-saving banner, although they have been reintroduced at a couple races due to safety issues.
Seems at some tracks the differences in tyre shoulder temps varied, from left to right, so much that they caused a number of high sides.



Outside of F1, are all race-slicks directional too?

[F1_eng]

Fil, I never worked outside F1 so my knowledge isn't 1st hand but I presume most racing slicks are directional.

Another interesting issue with tyre construction is the fact that each side can be different due to the way they are manufactured, this can cause a lot of problems. There is usually one side in the mould that has to support the weight of the rest of the tyre. This can cause inconsistencies in the compound.

[speedsense]

Fil, I never worked outside F1 so my knowledge isn't 1st hand but I presume most racing slicks are directional.

Another interesting issue with tyre construction is the fact that each side can be different due to the way they are manufactured, this can cause a lot of problems. There is usually one side in the mould that has to support the weight of the rest of the tyre. This can cause inconsistencies in the compound.

Very true, most racing tires (not all but most) are directional, as the rubber layering and molding process causes the directional orientation. Because the rubber is "lapped" over the top of the "circle" or donut of rubber in the the molding, the direction of the tire will be so that the overlap isn't running in a direction that the overlapped edge is striking the the ground first. The opposite direction or "correct" direction pushes it back on to the tire and is the "indicated" direction of travel.
Though some tires are not marked as so (with an arrow or such) it generally is done by the id number of the tire and which side wall it's on, when mounting.
This direction is purely because the tire could delaminate if run backwards and the possiblity and likely occurance that can cause separation of the rubber from it's cords.

[RacingManiac]

The tires for bikes definitely have different left and right shoulder compound, especially considering some of the tracks they run, ie, Daytona road course. The banking section puts tremendous stress on one side of the tire, where as the slow speed infield hairpins uses a different side....

[Scootin159]

Outside of F1, most racing tires I've worked with are NON-DIRECTIONAL and SYMMETRICAL. That means they can be run in pretty much any direction. I haven't worked with every tire out there by any means, but I have personally run both slicks and treaded rain tires from Hoosier, Toyo, Bridgestone, Yokohama, Kuhmo, Goodyear and Michelin.

The Kuhmo's are ASYMMETRICAL (thus meaning they must be always mounted with one side "out"), but they are non-directional. In fact, Kuhmo recommends switching them from left to right to balance wear. These are only asymmetrical in that they have two small tread "bands" (3/32" deep, 1/4" wide) that exist only to satisfy the racing body's "street legal tires" rule.

Almost all of the rain tires are directional - for wet usage only. In the rain, you always want to put the "V" shape pointing forwards (viewed from the top of the tire). However, if you're running "rains" in the dry (i.e. the Toyo's are a spec wet AND dry usage tire in Spec Miata), you can run them in either direction. The directional attribute is for the tread only, thus if they're either shaved, or it's dry, you can run them either way.

The rest of the tires (i.e. all the slicks), can be run in any direction. This is even recommended by many of the tire companies to balance wear.

[speedsense]

Outside of F1, most racing tires I've worked with are NON-DIRECTIONAL and SYMMETRICAL. That means they can be run in pretty much any direction. I haven't worked with every tire out there by any means, but I have personally run both slicks and treaded rain tires from Hoosier, Toyo, Bridgestone, Yokohama, Kuhmo, Goodyear and Michelin.

The Kuhmo's are ASYMMETRICAL (thus meaning they must be always mounted with one side "out"), but they are non-directional. In fact, Kuhmo recommends switching them from left to right to balance wear. These are only asymmetrical in that they have two small tread "bands" (3/32" deep, 1/4" wide) that exist only to satisfy the racing body's "street legal tires" rule.

Almost all of the rain tires are directional - for wet usage only. In the rain, you always want to put the "V" shape pointing forwards (viewed from the top of the tire). However, if you're running "rains" in the dry (i.e. the Toyo's are a spec wet AND dry usage tire in Spec Miata), you can run them in either direction. The directional attribute is for the tread only, thus if they're either shaved, or it's dry, you can run them either way.

The rest of the tires (i.e. all the slicks), can be run in any direction. This is even recommended by many of the tire companies to balance wear.

I question this remark, having raced ALMS (Michelin, Pirelli) and Formula Atlantic on Yokohama's, Grand Am on Hooiser's and Trans Am on BF Goodrich's. All of these tire companies specified these tires not be run on opposite sides of the car unless the tire was unmounted on the wheel and put on the other side rotating in the same direction. Simply putting the left tire by putting it on the right by changing the wheel/tire was concidered incorrect practice and endangering the possiblity of separation by "unfolding" the seam of the molding of the tire.
All of these companies reccommend the id numbers to be specifically run on either the inboard location (for instance inside on a right tire, outside on a left, for example).
You can't just swap the wheel/tire from one side of the car to the other... maybe I'm not mentioning a series you run in, but that's been my experience with racing tires, they are directional in terms of mounting the tire....

[Fil]

OK, I'm going to mess some of you up.
Formula One and MotoGP tires use different compounds on the same tire.
...And yup, that inner section is constructed of a compound harder than the rest of the tire surface.

whilst MotoGP, only this season, banned assymetrical tyres, and then allowed it again due to safety factors, i was under the impression that multiple compound tyres were banned in F1. Unfortunately i do not have the F1 Regs at my disposal to confirm my belief. Hopefully someone on this board can post up the relevant regs to back one of us up!

[Scootin159]

Outside of F1, most racing tires I've worked with are NON-DIRECTIONAL and SYMMETRICAL. That means they can be run in pretty much any direction. I haven't worked with every tire out there by any means, but I have personally run both slicks and treaded rain tires from Hoosier, Toyo, Bridgestone, Yokohama, Kuhmo, Goodyear and Michelin.

The Kuhmo's are ASYMMETRICAL (thus meaning they must be always mounted with one side "out"), but they are non-directional. In fact, Kuhmo recommends switching them from left to right to balance wear. These are only asymmetrical in that they have two small tread "bands" (3/32" deep, 1/4" wide) that exist only to satisfy the racing body's "street legal tires" rule.

Almost all of the rain tires are directional - for wet usage only. In the rain, you always want to put the "V" shape pointing forwards (viewed from the top of the tire). However, if you're running "rains" in the dry (i.e. the Toyo's are a spec wet AND dry usage tire in Spec Miata), you can run them in either direction. The directional attribute is for the tread only, thus if they're either shaved, or it's dry, you can run them either way.

The rest of the tires (i.e. all the slicks), can be run in any direction. This is even recommended by many of the tire companies to balance wear.

I question this remark, having raced ALMS (Michelin, Pirelli) and Formula Atlantic on Yokohama's, Grand Am on Hooiser's and Trans Am on BF Goodrich's. All of these tire companies specified these tires not be run on opposite sides of the car unless the tire was unmounted on the wheel and put on the other side rotating in the same direction. Simply putting the left tire by putting it on the right by changing the wheel/tire was concidered incorrect practice and endangering the possiblity of separation by "unfolding" the seam of the molding of the tire.
All of these companies reccommend the id numbers to be specifically run on either the inboard location (for instance inside on a right tire, outside on a left, for example).
You can't just swap the wheel/tire from one side of the car to the other... maybe I'm not mentioning a series you run in, but that's been my experience with racing tires, they are directional in terms of mounting the tire....

It may be just something that you get with the "higher-end" tires then. I have not moved up the ranks to "professional racing" by any means yet, as I'm still in the "grassroots amateur" level. As such, my experience is more with the types of race tires you can use for multiple races (many of us use the same set for a whole season) - not the nice "one & done" tires you guys get to use. It's very possible that we're only able to get away with the things we do because are tires are just more durable.

[Jersey Tom]

Even most amateur bias tires I've seen have had specific directions on how tires were to be mounted and ran, at least initially as stickers.

[F1_eng]

I know that even the tyres down to FSAE are directional, again having the tyre number on a specific side.