Street-tire class tires, stickiness & usefull life Options

[airsix]

For a couple of years I've been autocrossing in street-tire class with my 1.7 and I've always done ok - no wins, but no embarasments either. Until now...

This is my third year running these Dunlop SP8000 Sports - sizes 225/55-16 and 245/45-16 on 7" and 8" wheels. I know the tires are a little too wide for the wheels, but I bought them off a 944 and they came that way. I've just been using them up. I also know that this is an awful lot of rubber for a 1.7 - well I fully expected to have a fire-breathing six by now but you know what they say about best laid plans (let alone mine).

So there's the background. I've been running these tires for three years and they are close to being used up but they are not quite on the wear-bars yet. But... Either I don't drive like I used to, or these things just don't stick any more because I can't keep the car planted. I spun three times at the last autocross and I normally spin maybe once a year.

So my question: Do street tires "go away" just like race rubber after too many cycles? I don't want to blame the tires if it's me or something else wrong with the setup, but I'm trying to look for the most likely cause. Of late I have found that I can't even moderately trail-brake without losing the back-end. When I say loosing I don't mean it wiggles. I mean it's greasy.

Your musings will be considered and appreciated (even if the answer is "No man, tires are fine, you just suck"). (IMG:style_emoticons/default/laugh.gif)

-Ben M.

[r_towle]

I would say that the one thing that I learned that was most useful to me was this....

When the car feels like its about to spin, floor it.
Dont touch the brakes...but more important, dont let off the gas, give it more till you are past the problem...kinda feather it. You want to transfer the weight back, you have to much weight in the front, thereby lifting the inside rear wheel which causes you to spin...punch it and see how it feels, its not natural to do when it starts to go, but these little cars respond well to it.

And it goes without saying...get real tires....
Autocross tires are well worth the investment.

Rich

[Dave_Darling]

SP-8000 tires do indeed "go away" when they get worn. I always used to notice a really drastic improvement when I went from SP-8000 "slicks" (it's not illegal until you can't see any tread any more, right???) to "stickers" with full tread. The traction seemed to fall off gradually enough that I didn't really notice it until I put the new tires on.

Don't know if it's due to heat cycles or what, but very definitely the Dunlop SP-8000 (in 195-50-15 size) gets less sticky when it wears a lot.

--DD

[Part Pricer]

I don't have any real data to back this up. But, I would say your tires are all used up. I've found that I get a maximum of 2 seasons out of a street tire used for AX. When they get to the end of their life, they get very greasy. (It's either that or we both suck (IMG:style_emoticons/default/biggrin.gif) )

I've discovered a place where I have my own little secluded and protected (fenced in) parking lot where I go to test out things like suspension settings, tire pressure, etc. Last month, I went over there with two sets of wheels/tires. I had two-year-old street tires and my new Azenis. Same course, same car, same driver, different tires -- world of difference.

[SirAndy]

Do street tires "go away" just like race rubber after too many cycles?

yes, they do ...

[SirAndy]

sizes 225/55-16 and 245/45-16 on 7" and 8" wheels.

get the falkens!!!

they make them in 215/45 x 16 !!!
run those all around. you won't believe the difference ...

http://www.falkentire.com/tires/az_rs_sizes.htm

Andy

[Joseph Mills]

In the old days of yore, waaay back there (IMG:style_emoticons/default/biggrin.gif) your most effective AX street tire was either shaved, or worn to it's final 1/16th inch. There was no tread left to flex and two seasons was not long enough to effect the compound.

But modern compounds and tread design changed all this. It certainly has with AX specific tires.

Have you made any other changes to your suspension? Could toe-in, front or rear have been accidently altered? Front/rear brake balance working properly? Are you keeping a close eye on tire pressures? Just thinking outloud.(IMG:style_emoticons/default/unsure.gif)

You may have to adjust your driving style a bit to suit the autumn/twilight season of your tires.

If you decide to get some new ones, a friend also runs the Azenis and they are big bang for the buck. You could "downgrade" your wheel size at this time to a size that would have better synthesis with your 1.7 and have enough profit to pay for a new set of tires. And you will probably post quicker times. But then, the six dream would be over. (IMG:style_emoticons/default/w00t.gif)

[grantsfo]

sizes 225/55-16 and 245/45-16 on 7" and 8" wheels.

get the falkens!!!

they make them in 215/45 x 16 !!!
run those all around. you won't believe the difference ...

http://www.falkentire.com/tires/az_rs_sizes.htm

Andy

I second the Falken Azenis reccomendation. These tires are incredible. WCC event was my first AX in the 914 with new suspension so I dont have a base to compare to other tires, but the Falkens stuck like glue for street tires. I ran three 57 second times during the afternoon fun runs at the WCC AX once I figured out the course. I credit the Falkens for most of my speed as my driving technique wasnt pretty! I think somone with better driving skills could have turned even faster times in my car with these tires.

[Andyrew]

I dont think 225's are to big for 7's. Nor do I think that 245's are to big for 8's!

I think thats the max you should run though...

Asside from that. What they^^^ say!