Mazda Rotary Club

I have a brand new set of Toyo\'s on my FD that the import company said they put on when the car was over here as the ones on it where crap.  Can i tell from the tyre if its uk rubber or imported Jap rubber?  The back end is like a fat man on ice skates (all over the shop) even when no power is applied.  Need to get allignment checked but i thought i would look at the rubber too.

On a different note i spoke to my bro in-law and he can get tyres that are basically the same as goodyear F1\'s but unbranded for about half the cost - may bring some to a track day so we can test to see if they are any good.  They do ware down quicker but for low millage drivers could be a way of saving money.

hmmm maybe all good but i\'d always prefer to stick decent booties on my car as even with the easyness of 4WD the scoob was horrid on cheap rubber so not sumin i\'ll ever skimp on, too much ;), again......
Si (normally so tight as well )

oooh but to answer yer question er dunno how to tell if Jap or not :(
Si (AKA useless )

I dont think Jap Tyres have E makrings, but im not 100% on that.  If they are brand new you should be able to see they look pretty new which would give a good idea.

Lee

My silver rx is on jap and you would know the diff. Bring it round here and me and lee will drift her, then will find out....:rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin

Ok but if you break it i get your black one :D

Hi Graham,

Your tyres should have a serial number on them so how about you take note of these and e-mai Toyo and ask for a trace on the tyre ?

What pressures do you run ?

If it\'s any help l have known a few people run these with no real problems.

Checked just over a week ago and i\'m running 31 on the fronts and 29 on the rears.

Well that will induce over-steer.

For 16" rims you want 2.0 bar (26 psi ?) all round and for 17" stock size, 2.0 front and 2.2 back.

Im thinking it more likely to be your suspension settings or weather rather than the tyres themself.

Ive just had horrendous grip in this cold coming round a big roundabout, not too fast but it was trying to move all over the place.  I get it onto the dual carraigeway and give it a bit in 3rd amd the revs went up so quickly I thought my clutch had given out.  Turns out it was just wheelspin.  Must be very icy today.

I read an interesting statistic somewhere once, dont know if its true.  It was along the lines of a dry road at 0 degrees provides the same grip level as a wet road at 30 degrees (figures may have been slightly different).  Dont know if its true...

Lee

"Well that will induce over-steer"

Well, its not that simple. Are you saying that if you make the rear softer than the front, then you are inducing overrsteer?

What if you found the ideal pressure for the rear, and then over inflated the front,  that  would induce understeer, wouldnt it?

See this link:

http://rotarynews.com/view.php?id=223

QuoteOriginally posted by Martiny
"Well that will induce over-steer"

Well, its not that simple. Are you saying that if you make the rear softer than the front, then you are inducing overrsteer?

What if you found the ideal pressure for the rear, and then over inflated the front,  that  would induce understeer, wouldnt it?

See this link:

http://rotarynews.com/view.php?id=223

Nope
Take a car that is neutally set up.  If you either raise the pressures at th rear opr reduce them at the front you introduce understeer.
If you reduce pressures at the abck or raise at the front you introduce oversteer.

On 16" rims the car should have equal pressure all around, on 17" rims it should be higher at the back - the figures I quoted above are manufacturer ones.

Gman is running higher pressures at the front than the rear, this will eithger reduce understeer or cause (more) oversteer depnding upon the suspension setup.  In a car as well ballanced as the FD3S this sould also be noticeable.

Gary.
Could you give me some more help with this?

Lets say my car is handling neutral, and I have reached the optimum tyre pressures on all 4 tyres.

1)If I now raise the pressure at the rear, I am reducing the amount of tread in contact with the road. Y/N

2) Therefore, I am decreasing the amount of grip available at the rear, and this will lead to oversteer. Y/N

If no to either of these, then there is something else missing in the equation. Could it be: Weight Transfer? Tyre Temp?  I dont know, help me out.

I quote from "How to make your car handle" by Fred Puhn:

To reduce Oversteer:
Reduce weight Transfer at the rear by reducing rear roll stiffness.
Increase weight transfer on front by increasing front roll stifness.
Increase front toe-in.
Reduce aerodynamic downforce on front tires.
Increase aerodynamic downforce on rear tires.
Use wider rear tyres

There is no mention of adjusting tyre pressures in the above.


In another part of the book:
"Changing tyre pressures from the values that give the best grip is not a normal part of chassis tuning any more, and should be done only as a last resort"

Not totally sure on the mechanics but it follows along the lines that on increasing rear pressures .. while the contact patch is reduced, it is comparatively minimal in amount unless you go silly.  However the stiffness of the rear tyres is much increased, this can be especially noticable with tyres with softer side walls like the Toyo T1 proxes.

Tyre tuning is not a last resort, it depends on suspension travel, circuit/road type conditions.  Yes you should first adjust your shock rates if you can and ride height, however tuning may also be done through the tyres and this is the case of how cars are setup in race types such as CART.

Playing with the stiffness of your anti-roll bars has to be thoguht out very carefully.  Once done it can not be easilly undone.  This method will increase the overall stiffness to wheich ever end you do, but remember the break point for that end will come more suddenly and there is no easy way to adjust the effects.  IMHO I\'d never go for this option unless you are seriously racing or track daying the car and already know the handling characteristics of this vehicle.  Over-stifffened cars are a known source of accidents, especially on FR cars - check out other forums and archives such as the MX-5 lists for reference and other discussions.

If you want real advice then rather than reading one of the posted URLs on the \'Net, of which the advice varies and some times can be very wrong, you need to ask a known expert, i.e. some one like Chris Wilson (if you\'re on one of the email lists or bulletin boards he uses).

Hi Gary

I did some more reading up this morning, and you\'ll be pleased to know that we are in agreement!

If you\'ve ever seen this book, you will see that the author , Fred Puhn, is an expert, and Ill bet Chris Wilson has the same book.

Anyway, your original statements are correct, because manufacturers specify a tyre pressure way under the pressure for maximum grip.

My hypothesis assumed that the best tyre for grip had already been attained. That was the difference in our 2 examples.

I agree completely that fooling around with roll stiffness is a time consuming and tedious task! It is far easier to start with adjusting the pressures.

Your recommendations, of course, will work if you\'re  after a fairly neutral car, and not max grip. I was coming from a racing point of view, and now I see that we agree!

Thanks for the interesting thread and discussion! :-))

:)

I leanrt the \'interesting\' way - on the track doing track days in my MX-5 - initially playing round to reduce the slight over-steer.

Found 32/34 (front/rear) did quite nicely at brands indy in the FD3S, though tbh I wasn\'t pushing the car too hard round the bends being my 1st track event in it.

Hi Martin,

That book sounds like it could be worth picking up - is it this one?

http://www.amazon.co.uk/exec/obidos/ASIN/0912656468/ref=sr_aps_books_1_1/202-5486675-6302261

Cheers,

Rick

YES! Thats the One!  GO for it!  You wont be sorry!!!

(get the idea?)  :-))

Its makes fascinating reading. Even if you dont implement all the mods, you get a very good understanding of what the car is doing all the time. This can only make you a better ( and quicker) driver.

Had my wheels laser alligned - much better now.