Thanks for the tread difference measurements! I was actually quite curious myself since I went from the OEM RE050 setup to the 215/255 Azenis.

So since the tread width is actually less between the front and the rear, from 2.3 to 1.4 that shouldn't that be more of an oversteer setup like non-staggered??? I have a friend running 225/255 which should be even less of difference between front and rear tread? He has expressed more oversteer in the Autocross.

 

just saw this on tirerack, i hope it helps to claer some confusion!


Tread Width

The tread width is the distance between the outer edge and the inner edge of the tread of a new tire. However today's radial tires often feature tread designs that incorporate rounded shoulders and there is no industry standard pertaining to "how much" of the rounded shoulders should be included in the tread width measurement. Because of this, it is difficult to accurately compare the tread width differences of one tire brand to another. Tread width measurements are best used when comparing the various tire sizes or lines manufactured by a single tire manufacturer. Several tire manufacturers have chosen not to publish tread width dimensions.

 

36psi cold sounds more like autox'ing tire pressures than track... even on a cooler day. I run 32psi on the street. If I have to use the 615's this weekend(because of rain), I'll start out around 28psi at all four corners(245/275). I usually start my RA-1's at 24psi, but those sidewalls are much better.

 

I'm glad to see this thread. I used the 615's last weekend at CMP, 255 rear, 225 front. I started at 36psi cold all around and after a few laps they seemed to start giving up grip. I was ending up at 41 hot after the sesions so I brought the rears down 1-2psi. That didn't seem to help. My instructor mentioned that he was using them on his RX8, and that Falken suggested lower pressures, around 34-36 hot. I gave that a try too, starting at 32 front, 31 rear. This seemed even worse to me, ending at around 37-38hot. I've kinda come to the conclusion that either A:they don't grip that well at all or B:they just give up when they get warm. Also wonder how they will do with higher temps., this weekend was pretty cold, 30-50f.

 

I was at Big Willow with the 615's this last weekend. There's a little more oversteer with the 215\255 615's compared to the stock RE050's, but not enough to be concerned about or warrant a larger front sway bar IMO.

Not quite as much grip with the 615's compared to the stock tires, but I took them to the track with less than 300 miles on them so they're still quite new. I'll see if the grip improves with wear and time.

 

Then you have probably never driven the RE040's that come on the RX8 and 350Z. The first autocross I bumped them up from 32 to 38 cold and I was ice skating even with DSC/TSC full on. I then found out the sidewalls are super stiff already and you need to run them at 32/33ish, much better.

Also the 16" Hankook RS2's respond erratically to the wrong air pressures as well.

 

oversteer came from the set up or from tires overheat?