TYRES again, again, again

[jimj]

As Pete`s car handles like a pig on a skateboard on Grand Prix S tyres perhaps I`m missing something as mine doesn`t, or perhaps I`m missing something !
I can`t comprehend anyone having these "cup" tyres, road legal racing tyres, as they do on modern Porches and stuff. No matter how good they are in the dry any decent quality tyre is. My heart stopping, tank slapping, lip smacking, thirst quenching (?!) moments are always in the wet.
What tyre is really recommended for brisk, even very brisk on track days, all round, all weather performance?
Jim

[reb53]

Just to add a new angle to this age old discussion, has anyone seen the letter that appeared in the March 2010 issue of "Classic and Sportscar"?
I quote,

"Having owned a few Elans and Europas, I can tell you that it is difficult to find a suitable modern tyre. Most are designed for cars two to three times heavier and have very stiff sidewalls. Look for vintage tyres with soft sidewalls and you will be rewarded with unbelievable handling and the best ride of any car, classic or modern".
And,
" A Europa front tyre only carries 350lb and I believe the manual calls for 16-18psi. Most people over inflate-the tyres on a Lotus, resulting in a harsh ride and over-light steering".

Makes sense to me.
Comments?

Ralph.

[rgh0]

The Elan and Europa have always been light versus the tyres "normal" design weights both now and when new.

On the road you can use the lowish pressures recommended by Lotus when the casr where new for maximum comfort and OK handling but for maximum grip you need to up the pressures. I run my Elan in the 26 to 28 psi range all around on the track.

You really need to do tests with a range of pressures and use what feels good for you in tems of comfort and handling as there is no "right" answer.

cheers
Rohan

[oldelanman]

This article makes very interesting reading.......

http://autospeed.com.au/cms/title_Tyres-Grip-and-All-That/A_108915/article.html

Regards,

[Galwaylotus]

This article makes very interesting reading.......

http://autospeed.com.au/cms/title_Tyres-Grip-and-All-That/A_108915/article.html

Regards,

Interesting - yes but no entirely correct. Coefficient of friction between a tyre and the road surface is a moveable feast. There is a certain interlocking between the tyre material and the road surface otherwise it would not be possible to generate > 1.0 g and the coefficient of friction is not constant but rather it decreases with load which is why a lighter car is usually quicker all other variables being equal.

[msd1107]

There are other factors affecting the optimum tyre pressure.

The Elan uses a narrower than optimal wheel width, and that requires a lower tyre pressure.

Going to the +2 wheel width allows the use of higher tyre pressures.

On my Elan, I went up from the standard 18/23 to 23/28. After going to +2 wheels, I increased tyre pressures to 28/33. Cornering was better, and steering more precise.

You can visualize that as the wheel becomes wider, the tyre surface goes from rounded to concave. To get back to an optimally flat surface, increase the tyre pressure.

David
1968 36/7988

[jimj]

I`ve found that around 28 psi all round is a good compromise with Goodyears but back to the original question, what brand for all weather performance? Are the Michelin XAS good in the wet too?
Jim

[reb53]

"What actually influences the size of the tyre's contact patch? Is it the width of the tyre, or the profile? The simple answer that it is neither of these; the size of the tyre's contact patch is related to:

the weight on the wheel
the tyre pressure.
For example, say that the weight on the tyre was 900lb, and the tyre pressure was 10 psi. That internal pressure means that each square inch of area can support 10lb, so, in this case, the contact patch will be 90 square inches. If the tyre pressure was 30 psi, the contact area would be 30 square inches, and if the pressure was 90 psi, the contact area would be 10 square inches. "

I'm not so sure this is correct.
Surely the sidewall stiffness will influence how much a tyre will squash down under any given load, ( i.e. what its contact patch will be).

I'm thinking of an imaginery tyre that is solid apart from a tiny tube in the centre into which you can pump air. Would doubling the pressure halve the area of the contact patch ?

I think a lot more things come into play than this article would suggest,
( as others have already noted).

Ralph.

[twincamman]

well guys unless you are prepared to think like a racer your never ending quest for the all around sticky -good in the wet or stick in the dry or a cool road isn't ever going to happen >. ---If you plan to drive in a ;'spirited' manner daily be prepared to change tires each morning for the conditions before you head off to work . you need intermediate slicks for hot days for cool days soft slicks----- rains for English summer days ----so that's 12 wheels 12 tires and time to set the pressures for each condition of the day -and you will get 6 heat cycles out of the tire and then throw the tires away as they will have gone off and spend another 800 bucks for a set ---BTW tires slip on the wet ---just so you know -so buy an inexpensive set and drive according to the conditions --you are dealing with a 50 year old suspension so Bulgarian horse cart tires are better that the original equipment tires that came with the thing -- - --ed

[ecamiel]

OK - soft sidewalls are desired.
What are people using for winning street legal track/autocross tires on 13 X 6 or 7 inch rims? And where do you get them at the best price?

Eric
64 S1 SCCA flairs

[umbyfer]

I have new Dunlop SP10 on standard wheel 4.5.

Actually here in Spring north Italy (15-20 'C) i went up from standard 18-23psi to 20-25psi. For my road use only, sometimes fast road use, I am satisfied. The tires profile is a little round...

Shock absorber spax are set up with 10 clicks from soft, both front and rear.

Umberto
Elan sprint 7108000193K

[oldelanman]

I have new Dunlop SP10 on standard wheel 4.5.

Umberto, what size Dunlop tyres do you have ? I am guessing they are not 155/80x13"

Regards,

[umbyfer]

Roger,

sorry but you have lost: they are the correct standard size 155/80 R13. I bought last january on Internet here in Italy.

Regards,
Umberto

[oldelanman]

Umberto,
The reason I asked about the size of your tyres was because Dunlop told me a couple of years ago that they no longer make 155/80R13 tyres.

Dunlop are part of a group which includes Goodyear and Fulda and they suggested Goodyear GT2 or Fulda Ecocontrol were the only tyres they could supply in 155/80R13 size.

Regards

[twincamman]

the only 205 x 60x 13 I can find here are Sumotomo special order --they are to replace the Good Year blue streaks it came with and the Hancook tires I found to replace the slicks ---- a 13 inch tire is a thing of the past here ---ed