bky

Agreed. Alignment first. A good alignment is a night-and-day difference. It's a prerequisite before changing anything else.

japhethwar

Maybe want to think about a tire upgrade to go with that alignment. Riken tires are about as shitty as they come. Why be cheap with the most important part of the car?

DJT

Ok, I think I get it. But what exactly is "bump?" Is that the compression of the shocks / lowering of the suspension due to increased lateral load? IE., as the car goes around a corner and centrifugal forces are deflected downward to the suspension, the tire's camber becomes negative?

What exactly did they do with AP2s to fix this besides changing caster / camber / etc...?

SpitfireS

DJT > try to find a set of the "original" Bridgestone S-02 (ES02JZ) tires.
The S-02 225/50 rear is closer to a 245.
Any but Bridgestone S-02 rear "should" be a 245/45/16 to get close to the original width and the original tire stagger balance.

75% of your "problems" will disappear with S-02's all around and a UK-spec alignment on an AP1.
The final 25% you'll have to learn to handle.
That's fun!

ZDan

1. I wouldn't recommend S02s to anyone for any usage. There are better (and CHEAPER) tires than S02's available now. B'stone RE11, Dunlop StarSpec, and Yok AD08 will outgrip the S02 in the dry and give approximately infinitely better wet grip as well.

2. The effects of stagger on handling, particularly on a stock car, particularly on the street, are often GREATLY overstated. Long/short, the 245/45-16 "rule" for non-S02 rear tires was never strictly necessary, and NOW, with very few tires in that size available, the 245 rule is counterproductive (i.e., insist on 245/45-16 rear tires and you're guaranteed to NOT have the best tires for your usage).

die stickie die...

ZDan

Bump = wheel goes up relative to the chassis. On the AP1, rear suspension geometry is such that you get toe-in with bump, and toe-out with rebound. It's this *toe* change with suspension uppie/downy motion that gives the AP1 goofy handling, not camber changes.
During cornering, as the outside rear moves up relative to the chassis, and the inside rear moves down, the outside rear toes in and the inside rear toes out, giving less oversteer (or more understeer).
This might sound OK, but it is a very dumb idea...
Aside from making the handling a bit nonlinear and "spooky" feeling due to balance of the car changing significantly with roll angle, this "feature" also makes the AP1 particularly unforgiving of rookie mistakes. If you're cornering and you feel the back end begin to get loose, and LIFT off the throttle, the back end rises and the outside rear toes relatively outward, giving MORE oversteer (over and above the lift-throttle oversteer from unloading the rears)! It's like the car was *designed* to catch out the uninitiated.

In the AP2 they fixed the geometry, I believe by relocating the inboard pivot for the toe-link.

SpitfireS

Look at the data, all taken from official documents found on manufacturer's websites.
Go from an S-02 set to a RE-11 set and you'll change the stagger percentage by a lot.
IOW, you'll be driving around with much wider front tires.
Maybe (most likely) much more grip up front and just a little more grip at the rear.
Without changing anything else, IMO, you're asking for trouble when you get closer to the edge, especially with the AP1.
I've been looking at all the tire data because I know how my S2k drives on S-02's (and I like them, period, my opinion and I will recommend them too) and how the handeling can change by having a non UK-spec alignment, other tires or just one tire 0.1 or 0.2 bar off in pressure.
This fact and opinion makes me not very eager to change the stagger balance using the RE-11's
Believe me, IF I could use a set of 16" OEM size RE-11's and return them if I don't like them I would have done so allready.
I did drive the car (on a track once and a couple of weeks on the road) on 195/50 and 225/50 Yokohama A048's (R-compound) and the balance & handeling was/is just like OEM with more grip.

Some stickies still have a reason to live on ....

ZDan

I've never disputed that "tread width stagger" will change with non-OEM tires. Here's what I said:
"The effects of stagger on handling, particularly on a stock car, particularly on the street, are often GREATLY overstated."
I'll stand by that. It just ain't that big a deal. Quit worrying and just get the best tires in 205/55-16 front, 225/50-16 rear.

I've driven my stock AP1 on DOR R-compounds with treadwidth stagger ranging from .5" to 1.5". Difference in overall handling balance is not tremendously different. In fact, the only time I've actually spun the car at the track, I was on 205 front/245 rears, 1.5" treadwidth stagger.

On the street, on street tires, the difference will be even less.

The S-02's are not the best dry-grip street tires any more, and they were always somewhat diabolical in the wet. These days there's just no good reason to get them, particularly given that they're quite pricey!

You're overly fixated on published tread width data. There is MUCH MUCH more to actual tire grip than "tread width".

The stickie was, IMO, in the best of times when there were 245/45-16 tires available, overly insistent on maintaining tread width stagger or tread width stagger ratio.

These days, it's just obscenely bad advice, effectively insisting on substandard tires (the only way to get 245/45-16 street tires). Or as in your case indirectly suggesting that narrower fronts would be "better".

205/55-16 fronts with 225/50-16 rears is absolutely FINE on the AP1. It's quirky handling issues are more to do with rear roll stiffness bias and rear toe change with bump.

[QUOTE]Some stickies still have a reason to live on ....

bronxbomber252

When I went from 225/255 Star specs to 255 square on my 01 the only time I noticed a significant handling difference was at autox.... if you are not going any faster in a corner and there is no less grip in the rear than before there will be no change in the propensity to oversteer. Increasing front tire width increases the speed the fronts can grip at WITHOUT decreasing the grip in the rear in any way shape or form. It raises the limit and changes balance MINUTELY at that higher limit but does nothing to balance if one stays below the old limit.

Just Guy

Even though the S02's may have a .2 wider patch, you're still going to get A LOT more grip with RE-11's. There's no way in hell I'd put SO2's back on my car.

To the OP, I strongly suggest stickier tires and a UK Spec alignment.