Most people are running Toyo R888 in the street tire class around here (slalom (autocross) and hillclimbs).
I was curious about potential competitors, as I need new tires in spring.

In this review the Toyo R888 was beaten by all competitors: http://trackparts.ch/images/pdf/semislicktest%2012.pdf
(It's also interesting to note that the R888 is a pretty heavy tire in comparison)
Especially in rainy conditions the Pirelli P Zero Trofeo is faster than any other semi slick tire, which was also confirmed by the last review.
The Pirell P Zero Trofeo is available in 205/45 R17 which could be one of the quickest 17" semi slick option in a wet slalom event (autocross).
(Neither the Michelin Pilot Sport Cup+ nor the Continental Force Contact are available in any 17" dimension.)
(However, the Toyo R888 has never been a good competitor in the rain: http://trackparts.ch/images/pdf/semislicktest%2005.pdf)

In dry conditions, based on the following review and based on some online forums the Dunlop Direzza 03G should be faster than the Toyo R888, however it is only available in 235/45 R17 as opposed 235/40 R17. I'm not sure, whether the tire could make up for this gearing disadvantage.
http://trackparts.ch/mediafiles//Pdf...ktest%2013.pdf

Also, there doesn't seem to be any information about the Dunlop Direzza 03G on US forums (it is probably not being sold in the US).

(All these reviews are unfortunately in German, but if one has a specific question I can translate.)

I tried the R888 in the 205/40 R17 dimension.
In the last wet event I still dealt with hydroplaning but I was significantly faster than the competitors on wider tires and was even reaching maximum lateral accelerations of 1.1 g (and lost only half as much time to the guys running on non-road-legal racing rain tires).
However, in a dry event these narrow tires became greasy relatively quickly. I lost 3 seconds compared to last year on 235/40 R17 on a 3 minute long course.

So which is faster in 20min. HPDE session, driven by a seasoned intermediate driver (let's say Buttonwillow 13CW 2:05)?
1) 215/45R17 NT01 or equivalent
OR
2) 225/45R17 RS3
I believe they both heat cycle out and it is getting cold so getting and maintaining heats in the tires are not so much of a problem. I'm thinking of trying 215 but wanted to know if it is even worth the effort...

thank you

the extra 10mm of the RS3 wouldn't even come close to offsetting the greater performance from the NT01.

That's a fact.

Nice thread!

Let's say you are constrained between:

- 215/45 AD08R on 17x8

or

- 225/45 AD08R on 17x7.5

Which one would you choose for hpde?

Please, keep in mind that 225/45 on 17x8 isn't possible (not road legal) :(

Thank you!

Tire Width?
 

If you put 225/45/17 on stock wheel, make sure you put some camber in there. & it's better to run tires a little stretched.


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- 225/45 AD08R on 17x7.5 should be faster
- 215/45 AD08R on 17x8 would feel better

Depending on experience, you might think the car is sliding from the "floating" feel you would get from a tire that is wide on the wheel (the 225s here) and not push it as hard out of fear, in which case 215 would yield better times. If learning and/or having fun is primary objective instead of lap times for bragging rights, then choose 215.

Que? Lolwut?

I'm hoping something is getting lost in translation. What kind of rule would keep you from putting that combo on the car and driving on them?

He's in Italy. Some countries are very strict with tire and wheel sizes.

I saw that he's from Italy. Hence asking if something got lost in translation. My Italian is far worse than his English. But those particular restrictions seem to fail the logic test.

225/45's are okay on the car

8" wheels are okay on the car

Why would only the pinched/stretched extremes be acceptable? The only thing I can sort of think is if the combo puts the rubber outside the fender. But you'd have that problem with anything on the same 8" wheel. What local law/regulation does the 8"/225 setup actually violate?

But to answer the real question. It's an HPDE. The question getting asked means it's not likely to matter significantly. Bolt on whatever and go have fun.

I would choose 215/45 on 17X8.

:D

Thank you everybody for answering my question...especially TrqlessWonder cause i was waiting for someone to point out the crazyness in my request and his post made me laugh a lot :D

Sorry if this is OT but i think you deserve an explanation (and a good laugh about italian rules :D )

In Italy we must stick to stock tire size, but we can change wheels dimensions as long as they fit under the fender and tire is not stretched (this explain the 1st option, my free choice :) )
IF we want to use a larger tire we need to choose a tire-wheel combination certified by the wheel manufacturer hence the 2nd, quite illogical, option...courtesy of OZ :)

Back in topic, given your information i think i'd stick with the first option.

Correct me if i'm wrong but to me a floaty sensation means that a taller sidewall and a smaller wheel allow more slip angle if driven correctly (and i like that in 2nd or fast 3rd gear turn), but when i'm going fast (4th-5th gear) i believe what i want is the best feeling possible and i believe this is achieved only with the first opion, am i right?