18" rims...tire question

So after having 17" rims on my car, im thinking of going with 18 x 7.5 rims now. Anyone out there with 18's on their mazda3 sedan?? What size tires are you using that wont rub? any problems with rubbing after lowering it about 1.8 inches? I have the eibach sportlines on my 3. Thanks in advance for the the help.

Not sure with the Eibach Sportlines....I've been told by reliable sources (within Mazda) that a 18x7.5" rim with a 52.5mm offset and a 225/40R18 tire works the best. 

ok, i want to buy some rims thru mazda, and im looking thru the cd they gave me for mazda accessories i can buy.
now, im looking at the rims, and the rims i like are about $800, they 18's by the way.  is that for each rim or for all 4??
cuz the magnesium 5 spoke rim  for the RX8 is $2500, and that seems a lot for just one rim,
and the center caps are $60, which seems expensive if they were sold each.....
 
i really hope the rims are sold in sets of 4, cuz im sick of these black steel rims.
 

Those rims through Mazda are wicked expensive....

THANKS sstlaure, I think i might stay with the 17's if the 18's are gonna cause rubbing probems. And Dentinger, I agree...if youre going to spend that much from mazda, I think you can get a much nicer set of rims for less the price mazda is charging.

yeah but i think i was told that buying parts other than mazda parts would void my warranty....
but i unless those mazda rims are $800 for a set, ill definetely buy some non-mazda rims...
ebay has 18's for like, 300-400 dollars

good news!!
i went to mazda, and they said the puttinh on aftermarket rims would not void my warranty!!
which is totally bitchin' cuz i mazda rims ARE wicked expensive.
17"s are $400 a piece, and tires are an additional $300ish....a piece....

Damn...what tires are you putting on?  Anything that expensive will only last 10,000 miles (super sticky)

i got 18's on mine and got my 3 slamed and i dont rub at all ,

thats just what mazda told me...
so i'll probably just buy some used RX-8 rims (those fit on mazda3's right?) with the tires already on them...
or just some rims off of ebay...
and 18's wont rub will they?? like, what dimensions do i need?
and the costing in my previous post is in canadian dollars (btw)

The stock RX-8 tires on RX-8 18x8 wheels (225/45R18) will work on a 6, but not on a 3

For the 3 you need a 225/40R18

If I'm getting 18 x 7.5 wheels for my Speed 3 what offset should they be?

52.5mm is optimal, I believe 48mm will still work.  I used to work with some of the Engineers over at Mazda and they did a tire swing study on the 3 to see what was the biggest wheel that fit properly.  18x7.5 w 52.5mm offset was the result.  I'm sure there are others out there that have slightly different offsets that may work (although some people rub without knowing it....my 17x7 60mm offset rub at the front tires, full lock at the 3 o'clock position of the tire, but it rubs on a "friendly" surface and I hardly ever have it at full lock.)

if I'm looking at some 18x7.5 wheels with a 42mm offset will these work?

so then i can use RX8 rims no problem, i just need new tires??
how much will a set of tires cost?? like for all 4??
and will there be any rubbing??

RX-8 wheels should work fine (I've seen them on numerous 3's), people either run a 225 or 215/40R18 tire...You'd probably rub in a similar fashion as to what I experience on my car.  I've got 49,000 on my car now with no problems with the tires due to the rubbing I experience.
 
Depending on the brand/type tire, you should be able to get a decent tire for around $150 each or so.  If you want any kind of mileage out of the tire, you should target a wear rating of 300 or higher (lower numbers wear faster, but handle better.)
 
Not sure if a 42mm offset will work or not....Best bet is to go to a local shop and do a test fit.  42mm would probably require you to roll the fender lip a little in the back wheelwell to avoid scrubbing the tire as it compresses into the wheelwell (this can be done at just about any body shop)  Look inside the wheelwell and you'll see a 0.5" flange that would get rolled back on itself (currently sits at 90 degrees to the sheetmetal.)

i probably wont be lowering it... so would that make a difference??
and is rolling the fender lip hard??  like, im sure my friend and I could do it, cuz he's taking auto body classes right now....

Lowering changes the fit a little, but not that much.  Mainly at the front, when you are turning the tires.  I'm lowered and where I rub has nothing to do with the ride height of my car.
 
I've never personally rolled a fender before, but there are specialty tools that can do it with no body damage (I've heard of people using a bat to fold the lip up, but I would hesitate to do that if you don't know what you are doing.)  You basically fold that fender lip back in on itself to buy yourself an extra 8-10mm of clearance to the outside edge of the tire.
 
 

yeah, i looked at my fender today, and im sure my friend could help.
 
and i went out rim browsing today, just for curiosity, and new 18's, with tires, are gonna cost me at least $1500, which i dont want to spend.
 
so i think my best bet is to go to tirerack, or somewhere else that has package deals (wheels, tires, and balancing)...
 
and how much do you think shipping will cost me??  (im in canada btw, so tell me which currency so i dont get misleaded.)
 
and i was told the 18" tires would cost me about 140 each

Hey Dentinger, try www.wheelmax.com as they are always running specials on rims and tire packages and shipping is free on certain purchases. I am not sure if that includes canada so you might want to call 1st.

good website.
and i think i read somewhere on that site that the free shipping is only to the US...
oh crap, those are in US dollars, so the $900 17's suddenly seem expensive....

18x7.5 is what i got on mine i just ordered them like that with a 225 40 18zr tire i got my wheels from wheelmaxx.com i paid like $700 cnd if your not sure about the wheels just call wheelmaxx and they'll answer your questions they helped me

The Mazdaspeed wheels that are available are an 18x7.5"  Anyone know the offset of those specific rims?

which mazdaspeed ones??

These ones.....
 
http://www.mazdausa.com/MusaWeb/speedDisplayAccessoryDetail.action?endModelYear=2006&speedAccessoryId=215&carLineCode=MZ6&startModelYear=2004&categoryId=5