Tire safety problem

Hello. I have a set of Michelin Primacy (195/55/r15) on my 98 GSR. On my drivers side, rear tire, I am getting a weird bulge on the sidewall of the tire. It starts 3 cm out from the rim bead protector, and stops about 5 cm from the edge of the tire. It's about 4 cm wide, and the rubber near it is cracking and along the ridge of the bulge is cracking. I just knoticed this problem today and I was wondering if I can drive on this for a week or so (to get to work and back) before I can get new tires put on. I was planning on replacing my tires soon anyway b/c of low tread. Any advice on how dangerous this tire may be? I'm assuming it's leading up to a blow out through the sidewall. Of course no fast/hard driving whatsoever, I know that. I'm not planning on going above 50 mph either, don't have to for my commute.

I would appreciate it if you guys can help me out.

p.s- I'm looking at a set of Kumho Ecsta Supra 712 tires (205/50/r15) to replace them (any opinions on those would be helpful too, I can get a set of 4 for about 281 dollar on tirerack.com) They seem like a good/cheaper performance tire with decent life. I'll be going back to college, so I just need something I can drive on for a few years with hopefully good performance. Money is an issue.

You're looking at a blow out, expecially in the summer heat. When it bulges, it's getting ready to blow (especially when it's already cracking). And if you just noticed it today, there's no telling how long it's been going on. A week+ seems long to have that problem continue, hope you've got your donut in your car.

I'm not sure how the 712's compare to the 711's, but I've got the 711's on my car now. My friend had them on his car for a little under a year, and the tread went way down (also has an h22a swap and had bad toe). But I've had them for around 2 years now on my civic CX (no performance here), and they've only aquired a little bit of wear. They definently need to be replaced for next summer. So I'd say possibly 2-3 years worth of driving would do them in (if the 712's are similar to the 711's in wear).

That sounds right, I believe the 712's are the replacement for the 711's. They look like good tires.

Thanks for responding about the bulge, I was afraid that is what it was leading up to. I have my donut in the back of course, and I'll probably plan on getting those supra 712's tomorrow from a local store. The cost of getting them from a store is about 360 dollars, whereas tirerack + mounting fee from local shop = 320, so $40 is worth the comfort of mind that I won't blow out a tire. Had work today and I was extremely careful driving. I only raced one mustang. j/k ;)

And watch out for pot holes, curbs, and speed bumps; that will put more pressure on them as well.