mLeach

It seems to be pressure dependent too. Running on the lower side of the spectrum keeps them more consistent for me.

IntegraR0064

That's interesting. I was running the exact same pressures Lincoln and DC. Also tried it with a little higher pressures but ultimately settled on the same pressures at both places. 32-33 PSI range was what I settled on, also tried a bit higher (1-2 psi). What kind of pressures are you talking about?

iamxpl

hmm i had my pressures way higher i guess i since i dont have the proper wheels. most of you guys are probably STR set up?

IntegraR0064

Yep, STR. You'll need somewhat higher pressures if you're pinching the tires. Also always keep in mind there's variation in pressure gauges so don't believe pressures on the internet as gospel.

NFRad

True story.

iamxpl

noted! thank you gentlemen.

captain_pants

An interesting observation for me this weekend. Saturday was my first autocross on 255 Z2s on my AP1 STR car. I broke the tires in by driving about 60 miles on the highway and doing about a mile of 'slalom' on a deserted road.

The tires were quite peaky, with a very noticeable drop-off after you cross a certain slip angle. They really demanded precision more than any other tires I'd ever driven on. My driving style is a little sloppy, often exceeding the peak grip with some sliding. That hurt a lot with these tires! If/when you cross the line the car just slides and slides, being a little tough to bring back in line. This lines up with many of the tests I've read online.

Then my diff blew up on my 3rd run. So I hopped in a friend's STU STI for Sunday's event. He's got Z2s with probably 30 runs on them. They were a very different tire! Still quite 'crisp' feeling, but not so punishing if you exceed the slip angle that generates peak grip. I know, I know, STI vs. S2000, but I own one of each and autocross them fairly regularly so I can somewhat filter out the car differences. Very interesting! Now I want to do more and more runs to break these puppies in! I believe that many of the tests published so far used low-run Z2s that exhibit this peaky condition, and those reviews would change if they had 30+ run tires.

Now, anyone have an AP1 diff for sale?

--------------------------------------

On a side note: I got in themikewoo's AP2 for my final run on Saturday after my diff blew. Thanks Mike! He's on some terrible all-season tires that the car came with. Wow, that was comically fun! It felt like the car had 500 lb-ft of torque, with the ability to boil the tires on the slightest command from my right foot. Just a mere 6 seconds slower than my previous run. LOL!

iamxpl

haha! well ill report back in once i get 2 or 3 more events. i gave them a good work out last week during Evo School. these tires are indeed very demanding on precision. after i cleaned up my driving the tires showed great capabilities. heat management was amazing, i may have only sprayed them down once? still need to get a temp reader, which ill do this week. it wont be fancy, it will be one of those infrared temp readers.

imstimpy

Personally, I've never been able to scrub in a set of tires on the street, regardless of what I do. I do agree that the Z2s scrubbed in really fast compared to the Z1s. I'm posting this stuff again because my previous comparison of the Z1 and the Z2 was an old, cycled set of Z1s to a new scrubbed set of Z2s on my S2000. Just yesterday we did a seasoned set of Z1s against a seasoned set of Z2s on our STU STI. What we have found below is also echoed by a few of our local club members.

Dunlops have always been peaky. For those of you that like to be a little sloppy or ham-fisted (no offense intended), the BFGs and Hankooks tend to be your tire. I was about to say I haven't noticed a difference in peakiness between the Z1 and Z2, but as I thought about it there is something that just makes them very different that I'll try to explain. The Z1 feels a bit more progressive, but its best grip is found towards edge of slip. The Z2 feels like it flat-lines in grip, with a lot of room to play; going beyond that point isn't where you want to drive but it isn't hard to stay away from that drop-off. The end result is the Z1 allowing a lot more modulation of car attitude and the Z2 just is what it is.

**These results come with a big caveat: we have designed the suspension around the Z1 over the past 3 years.

At the Mineral Wells ProSolo we ran the Z2s in the morning, Z1s in the afternoon, then Z2s the next morning. We fought to drive the car with the throttle; it wanted to understeer, frustratingly so, but turned in competitive times. The sensation when going from the Z2s to the Z1s was that of slipping on an old pair of sneakers. The Z1s throttle-steered just right, and allowed a near infinite adjustment of the car mid-corner. Times dropped. Going back to the Z2s the next morning brought the understeer back with some further time improvement on one side. The left side was set on Z1s Saturday afternoon and the Z2s set the right side Sunday morning. Between the two, the Z1s felt way better but the Z2s could understeer themselves into the same times. We left with inconclusive data.

This weekend we ran the same two sets of tires, again starting with the Z2s first then switching to the Z1s. We bracketed pressures on the Z2s first, running 36psi, then 30psi, then 36psi. The tires talked more and slid more at 30psi, but ran the same times as the more precise 36psi. The first run in the Z1s immediately brought back the sneakers sensation, and dropped .2s for each driver on the "cold" runs. The car moved more, could be posited better, and just went faster. The Z2 times averaged 30.74s +/- .18s while the Z1 times averaged 30.21s +/- .17s. Both sets of tires were sprayed at 140*F but we did find the Z1s went to temp far faster than the Z2s and ambient was in the 90s. Ideally, we would have bracketed the Z2s again afterwards but we didn't have the time to do so.

Now back to the caveat. The Z2s have a lot of longitudinal grip. As a result, hitting the gas does not adjust the attitude of the car as readily as Z1s. Likely, to take full advantage of the Z2s we will need bias the car a bit more towards oversteer. Our S2000, on the other hand, was already a bit loose so going to the Z2s tightened the rear end and does not need further suspension adjustment.

Next weekend we will compare the Z2s to the BFGs while attempting to add the oversteer back to the STI.

daverx7

I have a Mugen AP1 diff for sale. You know you want it.

-D