With bad weather looming, we've had a lot of threads about tyres...makes, pressures and so on.
Can anyone give the benefits, or otherwise, of directional tyres, are they better?
Presumably the spare must be non-directional (or whatever the term is!)
S.
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I have no experience of this on cars, but they are used quite a bit on bicycles, and I have a lot of experience with them. On a bicycle the idea is that the rear tyre is pushing you along, so the grip is angled to increase the footprint under driving pressure. The front tyre however is just rolling, so the rolling resistance has to be reduced to save energy. Where the front tyre does the work is under braking, so the the tread is effectively the other way round when compared with the rear ones. There is a noticeable improvement in braking on a bicycle set up this way, though I couldn't say about the improved rear wheel traction. I would think on cars that directional tyres are only useful on rwd, since the front tyres on fwd have to do all the work of driving, and most of the braking as well.
Chris
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I think it's more to do with directional rain clearing patterns (Y shaped for example) than loading on road cars. if they are the wrong way round they will force water into the centre of the tyre - not good.
On the other hand racing tyres will be fitted with regard to braking and power forces applied. Non - directional tread patterns with direction indicators can be used in this way.
Piers
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I'm not sure about cars either, but I was staggered to learn a couple of weeks ago that motorcycle racers run the directional tyres both ways round, as they wear out on one side, and it gives them extra wear! These are not total amateurs either, the man I knows races in the supersports which follows the British superbike series. Having said that, there is no tread pattern on the side anyway when they are new, so that may well support Piers thoughts that it is to do with rain/wet.
Mike
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I never liked Physics or Mechanics but I do know that the Pirelli P-Zero's I had on my old Golf looked fab!
That's about it.
Oh, ref bicycle tyres, the directional off-road tyres are such to aid the flicking of material *out* of the tread - hence tyres will be rated on how well they "clear" to avoid clogging. Not sure if this is true of car tyres ref water removal.
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Guy Lacey wrote:
> Oh, ref bicycle tyres, the directional off-road tyres are
> such to aid the flicking of material *out* of the tread -
> hence tyres will be rated on how well they "clear" to avoid
> clogging. Not sure if this is true of car tyres ref water
> removal.
Not on my tourer they're not. Never leaves the paved highway. They do help with braking though. Mountain bikes are horrible dirty heavy things with suspension designed only to waste pedalling effort so that young hooligans soon become exhausted and can be caught by outraged drivers whose wingmirrors have been broken off.
Chris
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Chris wrote:
>
> Mountain bikes are horrible dirty heavy things with suspension designed only > to waste pedalling effort..........
Well Chris Ok I like horrible dirty heavy things (and presumably so does the missus ;-) but I do so agree with the comment about suspension wasting pedalling effort.
Do you remember the old small wheel Moulton's? You could get those on a real bounce going up hill and converted me to rigid frames for ever.
Stuart
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I have had both types of tyres on my car and definately belive in directional tyres. However directional tyres tend to be made by performance tyre specialists ie yokahoma so it might also have a lot to do with the compound on a personal note I prefer falken the compounds reasonably soft so gives reasonable tyre life but still gives superb grip for cornering and braking.Sorry for wafeling I guess what I wanted to say is you get what you pay for.
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My newer directional tyres are in a different leaguue of wet-weather grip from the old unidirectional. Same goes my Dad's Saab.
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I replaced the Pirelli P600s on my last car ('95 Cavalier SRi 16) with directional Yokohama A520s. The difference was immediately apparent. In the wet on P600s, you could feel the understeer when going aroung a sharp bend. On the A520s, there was no such tendency. Aquaplaning was a thing of the past. Wear rate was as good at the P600s.
And, the real killer - the A520s were considerably cheaper.
Andy
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I had directionals on my TWR Jaguar, the tyre roar was quite incredible.
Also the rear tyres were much fatter than the fronts, the spare matched the rears so a flat front left me stranded ... slight problem with non matching tyre sizes front and rear.
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