ninety4formula

What is the time difference between say the XS or NT05 vs. an A6 or 710? I'm not really concerned with being able to drive them to the event. Last season I had nitto NT555 street tires on the front and Nitto Invos on the rear. Would I notice a difference even just going to one of the street tires mentioned or would it not be worth it?

1991Z07

It depends on what you are running...

A the minimum you'll shave a few seconds off a short autocross course. When I went from street tires to DOT "slicks" I cut an average of 4 seconds off my times the previous year on a 45-50 second autocross.

You can estimate what you'll shave on a road course by timing cars of equal make/model/mods with slicks while they run. It'll give you a ballpark to shoot for when you change over.

AU N EGL

It depends . . .

more on car set up, suspension set up and driver skill, then just tires

ninety4formula

All I do is autocross. I can't imagine losing 4-5 seconds off a 45-50 second course. That would be sweet. That would put me in the running for FTD

ninety4formula

I know there are other variables, but assuming it was the same setup, what do you think the time difference would be just from tire swaps between the tires listed above?

L98Terror

2-4 seconds easy

The Panther

Stock C5 Coupe. Switched from NT555 (street tire) to NT-01 and cut ~6 seconds at Road Atlanta. Average driver at best.

AU N EGL

What lap times are you running at the Glen ??


From 4 to 10 secs quicker on VIR once you learn the new tires. AND you are on a fresh set of "A"s

Here are some NASA- NE time trial results

http://www.nasa-tt.com/Northeast_Regional_Results

This will give you ideas of times.

Track Records on NASA NE tracks

http://www.nasa-tt.com/Northeast_Track_Records

ninety4formula

I have never run up at the Glen, the only thing I have done is take their paced laps. I have done an autox in the paddock though and found a nice bump that made it so only one wheel was on the ground haha. That one didn't feel too good.

AU N EGL

Ok How long are your normal Auto-X sessions?

and how have you placed ?

Jason

Rule of thumb was 2sec on a 60sec course if I remember.
There are however a wide variety of thumbs.

ninety4formula

Our autox sessions vary depending on the lot or track we go to. They vary from 30 seconds to 1:20. When I race with the NCCC I do quite well. Last year I was very close to a 2010 WRX that had suspension mods, some stickier street tires, and some bolt ons. He ended up beating me, but over all I place in the top 10 consistantly I would say. My car was in BSP but my only mods were no cats or mufflers, a mail order tune, A.I.R. delete and small things. We have a good amount of SM and SSM cars though that have better suspension, brakes and tires so I think top 10 isn't too bad.

froggy47

4 sec on a 45 sec course is a stretch.

drivinhard

there are lots of threads about this on various forums, and the speed (or time) pick up always varies. I think one of the reasons it varies is types of cars. high hp cars need forward bite to run good lap times (autox or road course) lower hp cars don't. So they basically only benefit through extra corner speed, and braking. High hp cars benefit from corner speed, braking, and exit grip. Another way to look at it, the % of time you are WOT won't change as much in a lower hp car from a good street tire, to a sticky R comp. It WILL change a bunch in a higher hp car, and thus it's relative time (tire to tire) is probably going to be much faster.

AU N EGL

so maybe 1 sec quicker per 30 sec of run

ninety4formula

I could believe 1 second. I know that my car has a tendency to push into corners (whether I don't have the traction or too high of a speed into the corner I'm not sure). It is funny when you try to explain this to people though that haven't done it before. When people hear 1 second and they count it out loud, it doesn't sound like much, but people that do this type of stuff know that a second is a lot. I've lost races by .00x's before. It sucks! Here is a pic of the autox at the Glen I was talking about earlier...

SteveC68

http://grassrootsmotorsports.com/articles/measuring/

That is an article from 2010 that tries to answer your question. 1.3 seconds on a 44 second course.

ninety4formula

So if I read that correctly it is saying that there is a 1.8 second difference between the Kumho V710 and the Kumho XS on a 1 minute course. That is quite a bit. I thought I was going to get some 710's today but there was only one available....

Gordy M

A lot depends on what type of course you are running (tight or loose) and what tires are you comparing them to. In the last two years I ran both hoosier A6 and Hankook RS3's autocrossing and was looking at my times. On a momentum type course--fast and wide-- I was consistently 2.3-2.8 seconds quicker per 60 seconds. In a tight, narrow, technical course, I was consistently 3.5 seconds slower. The A6's allowed me to go deeper before braking, corner at higher speeds and have higher exit speeds. On a fast momentum course, I was able to keep the Hankooks holding very well but I still did not have the braking power of the Hoosiers.

95jersey

There are other things to consider. When moving up to R compounds those street/dual purpose brake pads you probably have been using will become worthless, you will need dedicated race pads. Also, your brakes will now run significantly hotter, so add brake ducts. You will eat through rotors at 3X the rate you did on street tires. Also, you will eventually deform you rubber control arm bushing, wear out wheel bearings, and with all that grip, the stock suspension will roll over like a **** on prom night, so now sway bars or new springs/shocks eventually.

While it is fun as all hell, and I could never go back to street tires, that extra 4-6 seconds is going to cost you big $$$$.