IS 300 Rims

will these rims be a good fit on my car I have IS 300 rims sitting in my garage powder coated black and never got a chance to actually put them on a car...is the center bore big enough or small enough to fit on the mazda3 or no

I don't know that anyone here will be able to answer that question for you.
You will have to know the wheel diameter and width, and especially the bolt circle and number of lugs, offset (quite important) and center hole diameter of the wheels in question.
If the center is too big I wouldn't worry about it too much as when the lug nuts are torqued to spec it's simply not an issue.  But you might be able to purchase concentric rings to adapt them to the correct diameter. I would use the plastic ones if available.  They're usually a lot cheaper than metal ones too. 
If it's too small, you have a problem and would need a machine shop to fix it properly.
 
Why would you want to use these particular wheels on you 3 anyway?  How heavy/light are they?
 
 

they are pretty light about 25lbs with rubber on them. I want to use them because they'r just sitting in my garage.  They are 5 lug and i don't know how big the bore is. 5 x 114.3 bolt pattern, 50 mm pr 55mm offset not sure 7 inch width.

Well, that all sounds pretty good!  Why not try them on for size?
25lbs w/rubber??  WOW!!  That's lightweight!
IIRC, the 3, as most modern Mazda's, have a 67mm (?) bore, but don;t treat that as gospel.
 

sh!it if the bore on the mazda is 67 then i guess these rims will be sitting in my garage for the next car....bore is 60.1mm on the IS 300 rims ...googled it....I REALLY want these rims on the car either the mazda or the altima i have either one...I put a lot of work into these rims they are full black with a gloss to them and they look mean as hell. 

Yup!  I just confirmed my guess.  Mazda uses a 67.1mm center bore on it's wheels.  Most AM wheels these days use an oversized 75mm.
 
Are you sure about that weight though?  My 17" AM wheels weigh in at 13.8 lbs. ea. and the tires, though not the lightest are ~21-22lbs. ea.
By comparison, the OE 17's are 19.6 lbs ea.
 
 

i will confirm that tomorrow...got to look for the wieghing scale...but how much do the stock rims weigh i have hub caps...

You have the 15" steelies.  Mine had the 17" alloys. 19.6 lbs. ea. w/o tires.
 
 
 
 

lucky you man i wanted the 17's...wanted the touring model but was out of price range, i want all black rims though and i will prob try to take these rims to a machine shop and see if they can make the bore bigger. I'm going for a rally type look not a luxury chrome rims look if you know what i mean. 

hmmm see i went with the 15" alloys. they look good and they get the job done. it only costs me like 20 more a month so i mean you get more options and it looks nicer then the shitty looking hubcaps (well they dont look too too bad but i dont care for them much. currently i got my snow tires so i can feel your pain lol)

 
I don't know if the 15" alloys are an option here in the States.  I'll have to check that out.  I know that the 16's are.
The HB's here ONLY come w/17" alloys, so it wasn't my choice, per-say, but I like them.  Just wish they weren't so heavy.
 
edit: Nope!  I just checked.  I built two i models, one sport (base) that comes w/15" steelies, and one i touring that comes std w/16" alloys. I don't see a 15" alloy avaialble here, J.
 
edit2:  WOW!!  To make matters even worse, I built the i (GS) Touring w/a number of options and accessories (still MTX) and the price jumped from $16,255 to $19,538!!!  That's more than I paid for my 2.3L HB!!!  Building an s sport with all the same options only cost $365 more!!
 
Tell me again why the i model is such a great deal?? 

paid 13 for mine...it was on sale so to speak the rest were at reg price. 

virgin,
I scratched the heck out of my 17" alloys on the right side due to poor parking on a friday night, and again during a freak snow storm where i went sideways into a curb...

with that said.....how would re-finishing the alloys work/look?

Do you have experience in this? 
 
EDIT:  here is a very descript discussion of someone dealing with this same issue...
 
http://www.autopia-carcare.com/realwhda.html
 
HAPPY DRIVING!

It looks like a lot of work, but a good system.  I used to buy and use Wurth hardware (the name/symbol on the paint cans) at various shops I had worked at.  It was good stuff imported from Germany.  Hi quality.
 
I scraped one of my OE wheels after my 30th HS reunion in a very tight parking garage.  I was not happy and always noticed the damage, even though it wasn't that bad.  I did file the rough edge off, but left the rest as it was.  Had I known about this system, I might've taken some further action.
 
I'd say, do it!!
 
 

i wieghed my rims with tires and it wieghs out to 44lbs ...thats a lot? or at least I think so. I am trying to go light weight or just keep it balance I dont want to add any weight that will affect cars performance.

Yeah, that seems kinda' heavy to me too.  What size are these wheels and tires you are talking about?
 
My 17" OE's w/the (215/50) Falkens on them weighed in around 38lbs. ea. The Good Year's (205/50 RS-A's) would've been a lb heavier.
The Kosei Racing wheels I'm running now, w/225/45 Kumhos are right around 35 ea.
 
They may not be worth the trouble.  You might just try and sell them for whatever you can get , then just get what you want.  Then you can look for a lighter wheel/tire combination.
 
 

I have yokohoma tires on those rims... dont know what kind BUT they are worn down real real bad If i was to put them on the car i'd have to change them, which most likely means the wieght will increase, these are 17x8 rims...ive been trying to sell these for a while now lol no one wants to buy rims..no buyers. i guess for now i will ride stock and keep my hub caps clean.

I'd say then that you may be asking more than the market will allow for them.
Have you tired Craig's List?  I sold my Gibson in one day, and got my price using it too.
 
 

well i found me some rims with tires for 400 which are some nice ass rims or at least in my mind only prob is i think they are too wide. 17x8.5 Volk TE-37 in gunmetal, The tire is a Falken Azenis 245/45/ZR17. 8.5 is the width though...too much for the mazda 3?

So are 245/45's!!  You'd have to do some serious modifications to the fender lips... and that's assuming the offset is even close to correct, which it proably isn't.
Pay close attention to the offset.  It is extremely important to handling, steering, braking, safety and premature parts wear.  If it isn't at least +45mm, stay away.
 
 

the offset on these are +50mm.....i found another set of rims "17 INCH TENZO SINKO DRIFTING RIMS". only prob with these are the offset is 42 and the rims are white...white car with white rims...I dont want to make it look like a honda civic. the width is 7j...don't know exactly what that means.