My sister's 99 Boxster's brake booster failed last year, leaving her without brake control, but it was the opposite effect. If she applied the brakes even lightly the pressure would sometimes hold like you were trying to put your foot through the floor, and they would not disengage for anything. Very unsafe, and I'm sure quite scary for her nearly getting stuck in the streeet not being able to move the car when the brakes did this.

I would think your booster may have just decided to give up the ghost around the same time you did the wheel swap, and in your case instead of the brakes locking up big time you're instead getting a delay in braking and a loss of braking power...failing closed instead of open, if you will, and not giving you the additional braking force it's supposed to.

I'm certainly no expert, but to me your issue doesn't sound like it's related to the wheel change. I think you're dealing with something strictly in the braking system.

And those wheels are quite nice.

A quick check to see if the brake booster is working is to put your foot on the brake - without the engine running. Start the car, keep you foot on the brake and you should feel the pedal depress as the engine vacuum pulls the booster diaphragm.
Its not foolproof, but a general check only......

False alarm, I think
 

Firstly, to answer the last couple of questions, the sizes are:

19x8.5 with 225/35R19
19x10 with 265/30R19

The tire sizes were the Tire Rack's recommendations, and the overall diameter is very close to the 17" overall diameter, so no speedo error, not that my speedo was that accurate to begin with...

And if the tires were slipping on the rims, I would think I'd be losing lots of air, and that's not the case. The Super Sports are funny-looking tires, with those rounded shoulders, I think that's what you are seeing.

I say my braking crisis is a false alarm, because I think the problem was ME. Or something boneheaded I did, anyway. I recently installed the 996 aluminum pedals, and to do this I hadda shove the seat way back. When I was finished with the job, I didn't bring the seat forward far enough, AND I also lowered the seat height. This changed my orientation to the brake pedal, and I just wasn't able to apply the same force I've been used to. Today I brought the seat forward where it should be, and whaddya know, my brakes seem to be back! I feel so stoopid about this.

But not as stupid as what ELSE I did today, which is rub one of my beautiful month-old CH-Rs against a Belgian block curb. Curse those Belgians! The stainless rim protector did it's job, and the wheel itself only took a tiny hit, but the protector is toast, in the way only stainless steel can irretrievably bend.

Now I hafta find out how to get a new protector on there. The Tire Rack told me that I could NOT buy extra protectors, since only BBS in Georgia would be able to mount a new one, but c'mon, it is just a metal ring clipped on and backed with foam tape. Shirley, they can't be serious. I guess I'm gonna find out.

If someone knows of a source for the ring (protector), please let me know.

And thanks so much for all your suggestions. If I manage to unconvince myself that the problem was just that my leg was having to stretch for the pedal, I will be following-up on them.

I think you should also change the pads is the pad material thicker than the backing plate?

A picture is worth a thousand curse words
 

Yes, Ckrikos, I have a quarter-inch or better of brake pads left.

Here's a pic of today's damage. It looks worse than it is in this pic. I can peel-off the protector without a problem I think. That foam tape is going to be a pain to remove, though. I have Goo-Gone, which works painfully slowly. The only REAL damage to the surface of the wheel can be seen under the curve of the wrecked protector.http://986forum.com/forums/uploads01...1370047549.jpg

Darn!

congrats for not blaming it on your wife!

LOL! Nah, it was all me this time. But the dent on the fender, the scratch on the nose, the chip on the console...those are all hers. Plus there is a faint smell of spilled coffee in the passenger footwell...

I've now removed the wrecked rim protector, and I was wrong, it is not clipped and stuck on with tape, it is actually only stuck on with the dreaded foam tape. I got the tape off with Goo-Gone worked-in with a toothbrush and a LOT of rubbing of gooey foam. Uck!

I've contacted BBS about buying some more rim protectors, waiting for their answer.

Just to be sure, I have now examined all my brake pads, and they all have plenty of material left.

Replacement on way
 

Just to finish off this thread, BBS in Georgia does indeed sell replacement rim protectors for $54ea plus shipping.

Can you share what offset you are running thanks...

Sure. The offsets are ET 51 Front and ET 38 Rear.

The rears are right on the edge of what I find acceptable (meaning that they are out from the car enough that if they were any further out they would stick out and I wouldn't like it.

The fronts seemed fine to me, and I ran them for a few weeks without any spacers, but I eventually put on 5mm spacers to get them to better match the rears, and now I consider their placement to be perfect. Can't say I noticed any difference in handling by widening the track by the 10mm. Using the spacers therefore becomes a purely aesthetic mod.