225/45/18 on 18" X 7.5" Wheels

[speed3convert]

Has anyone had any actual experience with this combination on a Mazdaspeed 3?

I just bought an '07...

I plan on using the OEM wheels with snows as my winter set-up (I live in the Northeast) and running aftermarket 18" X 7.5" for the summer.

Offset would be critical here, I suspect, in order to avoid "rubbing."

I'm considering some ASA AR1 wheels in 18" X 7.5" with an offset of +52mm (from the Tire Rack).

Will those specific wheels fitted with 225/45/18 rubber fit without "rubbing??

 

[aaronc7]

haven't done anything personally, but from all I've seen, yes you should be totally fine. Why not go with 225/40?

 

[udontknowjack]

225/40/18 without a problem on my....same wheel size u talk about....

 

[speed3convert]

haven't done anything personally, but from all I've seen, yes you should be totally fine. Why not go with 225/40?

The OEM tire diameter of the Speed 3's stock Bridgestones is 25.7" per the Tire Rack's site.

The Tire Rack lists specific diameters for virtually every tire they sell; a 225/45/18 is typically around 25.9", which is just 0.20" larger than stock. That's a very small variation and the slightly higher sidewall works in favor of preventing a bent wheel.

It's worth noting that calculating tire diameter (using the advertised width, aspect ratio and diameter) doesn't always yield precise results. Published data (e.g. from The Tire Rack) often times shows significant variations in diameter and tread width among tires that are supposedly "the same size" (e.g. 225/45/18).

Some 225/45-18s (e.g. Pirelli P Zero Rossa) have EXACTLY the same rolling diameter as the stock MS3 215/45/18s Bridgestones!

The 225/40/18s tend to have diameters of around 25.1". That's a difference of 0.60" from stock, which is 3 times as great as the difference with the 225/45/18. So the 225/45/18 is much closer to the stock diameter.

It's not at all uncommon to bend aftermarket 18" wheels in this area (the Northeast). I know several people who have done that. My best friend bent TWO of his Centerlines and they are FORGED! The 225/45's taller sidewall gives more cushioning to absorb impact loads over potholes, etc.

I also noticed a much larger selection of tires in the 225/45/18 size.

Based on all of the above, a 225/45/18 seems like the logical choice for street use. The 7.5" wheel width is a no-brainer - provided that offset is correct. 225/40/18 would probably be the better choice for competition events, but I plan on doing all of my driving on the streets.