245/40/18's + RX8 wheels

Sorry for the late clarification. I'm oversees on business...

I have 235/40/18s mounted on the recommended 18" x 7.5" x 48mm rims.

These do not rub under normal circumstances. They also do not look like they should ever rub. HOWEVER, if you have a couple of adults in the back and you hit a big bump, the rear tire can make contact at the 10:00 position of the inside fender. This is not speculation. It happened to me, bent the inside of the fender and also took a chunk out of a tire. I had it fixed for $100 by having the rear fenders rolled.

I dont see any way you would go 1/2" wider (i.e. 245s) without this same problem.

Sorry to be the bearer of bad news. I still think going with larger tires/rims is a great idea. Just gotta be a bit careful in the back...
 
Maybe but 245s add around 1/2" in width making them almost 1 1/2" wider than stock. I dont see how this will work unless the fenders are rolled...
 
someone going to try this?

I'll post some pics of my 255 & 245 setup from my s2k as perspective :-)

big err... wide difference
 
Dream said:
Im a chicken, I just ordered 235/40.
Click to expand...

Fourthmeal has a link to a terrific calculator for comparing different wheel/tire size combos. According to it, you picked what is just about the closest in diameter to stock of all the popular options, so those tires will give you more grip, look cool as hell and not totally screw up your speedometer.(cool)
 
Mid_Life_Crisis said:
Fourthmeal has a link to a terrific calculator for comparing different wheel/tire size combos. According to it, you picked what is just about the closest in diameter to stock of all the popular options, so those tires will give you more grip, look cool as hell and not totally screw up your speedometer.(cool)
Click to expand...


Ya I saw that, I dont have time for rubbing issues. RX8's are in powder coat as we speak, should look hot. (cabpatch)
 
Dream said:
Im a chicken, I just ordered 235/40.
Click to expand...

aw, man!
was lookin' forward to seeing the 245s on there, oh well. lol


by the way, not to thread jack but, 07speedfreak, need more pics of this.
p1010479bgt7.jpg


looking good!!!!!!!!!!!
 
I have noticed while putting on my RX8 wheels (for autocross) that there is only like 1/2" roughly of clearance between the tire sidewall and the front strut...
I currently have a 225/45/18 tire on there...will the 235/40/18 fit without rubbing the front struts...? (huh)

Here is a video of my autocrossing with the RX8 wheels:
<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://i44.photobucket.com/player.swf?file=http://vid44.photobucket.com/albums/f19/Milkywayman22/Mazdaspeed%203/Autocross/Martin%202-17-08/MOV02489.flv">http://s44.photobucket.com/albums/f...in 2-17-08/?action=view&current=MOV02489.flv]

I really like these wheels. The MS3 should have been equipped with these!! They look so cool when driving (look at the 27 sec remaining section of the video)!! (2thumbs)
 
Last edited:
udontknowjack said:
a few alrite tried 245 on 18x8 50+ offset ...it only rub once in a blue moon...
Click to expand...

think jack is refering to me, almost a year ago I put 245/40/18's on my car with weds 18x8 +50's
I am on stock springs with bilstein shocks, so my height should be stock.
If I have weight in the back, when I hit a dip in the road and the rear suspeneion compresses, the rears WILL rub a hair on the fender lip. If you dont mind rolling the lip, you will have zero fitment issues.

For autox I run 245/40/18 A6's on the front on a 18x7 +50 rim and they rub a C hair on the front inside of the wheel well at full lock. In the rear I run 225/40's so there is no issues, im not gonna have a $265 dollar tire get chewed!


anyway, if I was lowered, no way would 245's fit without fender modification, which I think someone should look into! 285's on the front, FTMFW!
 
I know I already gave the link but I made it even more easier to help figuring out. We'll be able to compare by visualizing the popular packages. I dont think nobody runs the 35mm offset but I gave a couple measures anyway with the 7.5" wheels. All packages have the initial MS3 stock wheel/tire setup for comparison.

MS3 vs 18x7.5 --35mm + 235-40-18
223171.jpg



MS3 vs 18x7.5 --35mm + 245-40-18
223172.jpg



MS3 vs 18x7.5 --45mm + 235-40-18
223173.jpg



MS3 vs 18x7.5 --45mm + 245-40-18
223174.jpg



MS3 vs MS3 + 235-40-18
223175.jpg



MS3 vs RX8 + 225-40-18
223176.jpg



MS3 vs RX8 + 235-40-18
223177.jpg



MS3 vs RX8 + 245-40-18
223178.jpg


I cannot confirm what the "calculator says". But you can make good comparison with an existant package that for sure works, for instance.
 
Last edited:
So are people running 4 "front" RX-8 wheels? The RX-8 is RWD so obviously the offset front/rear is different (or is it)?
 
Then the consensus here seems to be that RX-8 wheels + RX-8 tires (225/45R18) fits fine. It's when you start getting wider tires or shrinking the sidewalls that it's "at your own risk".

From what I see on Tire Rack, there's plenty of choices in that tire size. My biggest problem is that no one makes winter tires to fit the stock 215/45R18 tires. I'm thinking I may just buy a cheap set of 17" wheels and get dedicated snow tires for those.
 
dparm1984 said:
Then the consensus here seems to be that RX-8 wheels + RX-8 tires (225/45R18) fits fine. It's when you start getting wider tires or shrinking the sidewalls that it's "at your own risk".

From what I see on Tire Rack, there's plenty of choices in that tire size. My biggest problem is that no one makes winter tires to fit the stock 215/45R18 tires. I'm thinking I may just buy a cheap set of 17" wheels and get dedicated snow tires for those.
Click to expand...

The 225/45/18 on the RX-8 wheels fit fine...no issues at all.

The question is, do 235/40 or 45/18 fit without concern... (huh)

Every time I mount my RX-8 wheels with the stock 225/45/18s there is only one pointer finger thickness (with mechanics gloves) clearance between the side wall and front strut. I measured my finger and its roughly 1/2". I am not sure about mounting a 235 now. But I really want to...
 
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