Tyres - Directional vs Not... and Tyre size

poison · Post by **poison** » Mon May 21, 2007 10:48 pm

Shermio wrote:Yeah need a new set myself soon...
R16 205/45 (I want unidirectionals)

Hi Shermy, how's it going. Why unidirections

most people seem to be fond of directionals, for no other reason I had assumed them to be better...

And FYI in case anyone is considering a size upgrade, 15" are so so, 16" are great but 17' are too much hard work on windy bumpy roads, but great on the smooth stuff.

Shermio · Post by **Shermio** » Mon May 21, 2007 11:06 pm

Hmmm I thought unidirectional are tires that go in one direction, i.e they have the following tread pattern:

|V|
|V|
|V|

As opposed to non-directionals:

|//|
|//|
|//|

I like them over non-directionals because they are in my opinion better in the wet and from previous experience they have less noise... (Had a set of Falkens Ziex) they were very nice and the breaking point was very predictable where one could easily control the amount of slide.

poison · Post by **poison** » Mon May 21, 2007 11:19 pm

Ahhhh... good use of the keyboard there

Yup we are both talking of the same thing, they are Directional tyres. can only be used to rotate in a single direction.

Post by **zorruno** » Tue May 22, 2007 9:28 am

The majority of performance tyres seem to be directional these days.

If you have a noisy tyre, it will unlikely be due to it's directional nature - just the brand/quality/design of tyre. You can get nice quiet directionals... actually, it should be easier to make a quieter 'directional' tyre, than not - as when designing, they will always know the intended direction of rotation and can design to suit.

For the same reasons, it should be easier to make a better 'wet' performing directional tyre too.

MatBat · Post by **MatBat** » Tue May 22, 2007 10:39 am

Some would argue that Asymetrical tyres are the best way to go, they offer the benefits of both directional and unidirectional, most of the top end tyres such as Michelin, Pirelli etc. have asymetrical tyres for Ferrari, Maserati etc.

The cons to thses tyres though: The price!

Shermio · Post by **Shermio** » Tue May 22, 2007 11:46 am

The OEM tyres are horrible on mine in my opinion, The Turanza are a bit too hard on the compound and as a result I tend to have them at a lower PSi 32 but now that they are wearing the outsides I have them upped to 35psi and in the wet they can be 'fun'

I just have more faith in directional than asymmetrical in the wet... the directional channel the water to the outside of the footprint while the asymmetrical tend to channel them in many different directions thus increasing time the water is in the thread...

Just my 0.2

Growler · Post by **Growler** » Wed May 23, 2007 1:49 pm

poison wrote:And FYI in case anyone is considering a size upgrade, 15" are so so, 16" are great but 17' are too much hard work on windy bumpy roads, but great on the smooth stuff.

With any low profile tyre you have to run soft springs as there is no "give" in the sidewall...hence all of the hard work.

Shermio wrote:The OEM tyres are horrible on mine in my opinion, The Turanza are a bit too hard on the compound and as a result I tend to have them at a lower PSi 32 but now that they are wearing the outsides I have them upped to 35psi and in the wet they can be 'fun'

35psi is too much for an MX5 as it is a light car. Even on the track with 15's I would only look at 33 - 34 max. If you are wearing the outsides of the tyre I would look at your suspension settings.

Growler.

Shermio · Post by **Shermio** » Wed May 23, 2007 11:11 pm

Hmm it was recommended to me by the tyre guy... I normally had it at 32PSI but they tyre guy told me that both the inside and outside was wearing down a bit and that the tyres should have more pressure in them... Im running on stock suspension.... just had them checked and they were perfect...

Paul Murray · Post by **Paul Murray** » Thu May 24, 2007 9:58 am

Shermio mentioned the tyre wear on the inside and outside, I had a similar problem on our VS Holden which was shod with Dunlop LeMans and under inflation was the cause of this. The pressures are now kept at 32 psi and increased to 35 psi when towing the horse float and even wear is achieved.

My mx5 185x14 on Panasport worked really well on the grid II & III"s. I switched from Bridgestone to Dunlop Direzza some 60k ago and have found similar road holding qualities although the Dunlop feels a bit more stable in the wet. I also run 32 psi with these and easily achieve 40k per set with some spirited driving at times.

Shermio · Post by **Shermio** » Thu May 24, 2007 10:59 am

My mate just came back from Dubai and says that over there tyre pressure in the high 50's are pretty normal... and even 60's with those insane on-road drifting that we see so often on YouTube

Trevor · Post by **Trevor** » Thu May 24, 2007 6:42 pm

Shermio wrote:Hmm it was recommended to me by the tyre guy... I normally had it at 32PSI but they tyre guy told me that both the inside and outside was wearing down a bit and that the tyres should have more pressure in them... Im running on stock suspension.... just had them checked and they were perfect...

The tyre guy was correct. Not difficult to understand that more pressure will increase the centre contact area, within the contact patch.

Baadfast · Post by **Baadfast** » Thu Mar 06, 2008 8:07 am

Various sources I've read about tyres expound a couple of theories.
1/ Tyre pressure is determined by the car manufacturer and it's best to use their recommendation and add 4 psi as a starting point. The logic being that the tyres pressure is relative to the cars weight and not the tyre manufacturers specification. Imagine the same tyre on a MX5 and a Falcon XR6 using the same 35psi pressure, one of them surely isn't going to handle like it should ?
I've new Bridgestone 205/45/R16 on the rear and the 'local tyre guys' said 35psi. The 'Bridgestone technician' said car specification +4psi, which is 30psi. Mazda also say car specification +4psi.
My wheel alignment is heavily performance biased so wear isn't the issue ... staying on the road is.
I'll start with the lower and see how it goes ... thoughts chaps ?

2/ There's a residue on newly manufactured tyres from the mould preparation solution they use and new tyres need to be 'run in' before their pushed hard. Again I phoned the Bridgestone head office and talked to one of their technicians and his take was.
He's sure the tyres are well cleaned and prepared before they leave the factory so he thought it was a bit of a 'urban myth' but he did say that if you did want to be sure, to do a 150km before you push them.

SLYDIT · Post by **SLYDIT** » Sat Mar 08, 2008 9:03 pm

EVERYBODY SING IT!

T1-R T1-R T1-R T1-R T1-R T1-R T1-R T1-R T1-R T1-R T1-R T1-R

THE T1-R was redesigned with solid outer edges to stop the edge wear found on the GSD3 and T1-S, meaning you dont have to run too much pressure to keep the wear even. The T1-R is also a lighter tyre compared to the Bridgestone.

Baadfast · Post by **Baadfast** » Sun Mar 09, 2008 4:14 pm

I'll start a different topic as this one seems now to be for those with 'special needs'

Sugoi · Post by **Sugoi** » Sun May 11, 2008 10:46 am

Hi There,

I am in need of new tyres for my 1992 MX-5. I have the stock alloy rims and the current tyre size is 185 65 R14. Can I get wider tyres to use on the stock rims, also what width would you suggest? I was thinking about going wider, with a lower profile. I get the general feeling from reading here that the Toyo T1-R, gets a good rap, would these be suitable for a car that sends most of its time around town? What about Pirelli's have people found these to be any good?

Any suggestions ?

Ian · Post by **Ian** » Sun May 11, 2008 2:28 pm

The correct tyre size for your model is 185/60 x 14.
T1's are great but not sure you can get them in that size. With a 5.5" rim width you should stick to this size and profile and get the top tyre in a recognised brand. Paying a fortune for an 'exotic' brand tyre is unnecessary.

Cheers, Ian

Growler · Post by **Growler** » Mon May 12, 2008 12:39 pm

You can go 195 on a standard rim with no issues at all.
In fact you could go as wide as 205 but you will get a lot more sidewall movment.

poison · Post by **poison** » Mon May 12, 2008 3:07 pm

On the subject of tyre width maybe someone can answer this for me. In Japan I saw quite a very wide rims fitted with skinny tyres. The result is odd looking with the side walls angling in a lot from the rim. Is there any benefit in this at all?? Cheap drift tyres? I have no idea, and it’s puzzled me for a while. I can’t even imagine that it’s that road safe.

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Growler · Post by **Growler** » Mon May 12, 2008 5:01 pm

poison wrote:On the subject of tyre width maybe someone can answer this for me. In Japan I saw quite a very wide rims fitted with skinny tyres. The result is odd looking with the side walls angling in a lot from the rim. Is there any benefit in this at all?? Cheap drift tyres? I have no idea, and it’s puzzled me for a while. I can’t even imagine that it’s that road safe.

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On the race car I have a 10" wide rim with a 9" wide slick. This is designed to reduce sidewall movement as much as possible as the slick is a soft compound with soft sidewalls. V8 Supercars don't have to run that combo as the tyres are constructed with a very stiff sidewall.
I'm guessing drift cars run wider rims than tyres for the same reason. I'm guessing they want the tyre not to move and to reduce the grip so they can fling it sideways.
Again I'm guessing the japs think it's a cool thing to imitate the real life racers so thats why they have them.

Ian · Post by **Ian** » Mon May 12, 2008 8:17 pm

Growler wrote:You can go 195 on a standard rim with no issues at all.
In fact you could go as wide as 205 but you will get a lot more sidewall movment.

Ummmm...there is one issue that readily comes to mind...speedo accuracy. (assuming 195 is used in 60 series profile) It is interesting that when Mazda increased the rim width of the 14 inch wheel by half an inch on the introduction of the 1.8 engine, the tyre size remained at 185/60.
Given the OPs original stated use as mostly for pottering around town, going up in tyre size on factory rims has little to recommend it other than as an exercise in spending more cash than is really required........

Post by **jif** » Mon May 12, 2008 9:53 pm

lol - going to a taller tyre actually makes the speedo more accurate (or less inaccurate) ... it's about 5% optimistic !

those trailer speed radar sign things are great

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