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225/45/18 vs 225/40/18

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225/45/18 vs 225/40/18

  #1  
Old 01-14-2011, 02:26 PM
1st Gear
Thread Starter
Join Date: Jul 2010
Posts: 19
Default 225/45/18 vs 225/40/18

Hey folks, was hoping I can get some opinions. I'm looking to get some new tires and rims for the summer. I just recently purchased Koni FSD / Eibach suspension kit, but have to install. From what I've read online, the drop is around 1.2-1.5 inches.

What would you guys recommend as my tire size? I really don't want any rubbing to occur, especially since I live in Montreal, where the roads are only re-paved once every quarter century.

I like 225/45/18, simply because it will only add to the improvement of ride quality. But I am not sure if it diminishes my braking and my cornering.

225/40/18 is obviously what most people use, but I'm skeptical since the tires are much thinner, which equates to a much rougher ride, and as I said before, I live in Montreal.

Any help would be greatly appreciated... FYI, I currently use 17" now for the winter, with stock Audi wheels.
 
  #2  
Old 01-20-2011, 12:15 PM
1st Gear
Join Date: Sep 2009
Posts: 1
Default

I have been told that the quickest way to verify that an alternative tires works for your car is to multiply the 2 first numbers together and if the difference is less than 3% (225 x 45 - 225 x 40 < 3% ) you are safe. The main issue in using an alternative size is the breaking. Under 3% the effect is negligible.
 
  #3  
Old 01-24-2011, 04:00 PM
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Join Date: Sep 2010
Location: San Diego, California
Posts: 9
Default

http://www.miata.net/garage/tirecalc.html is probably the easiest to use tire size comparison online.

As to recommendations (braking, rubbing, etc.) that's another story, I just wanted to share the link
 
  #4  
Old 09-23-2012, 10:47 AM
1st Gear
Join Date: Jul 2012
Posts: 48
Default

Hey Everfresh. Did you ever put these 245s on your car? I also would like to do the same. I think the ride on the 240s on the 18s is too harsh. I can't even imagine what it must be like with the sport package! Yikes! Like driving on square boulders.
 
  #5  
Old 09-25-2012, 03:44 PM
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Thread Starter
Join Date: Jul 2010
Posts: 19
Default

My A3 is premium and not sline, but as of right now my setup is running Koni FSD struts on Sline springs. Drop is immediately evident, and the ride is day and night since I had been running on stock struts that had more 85,000 miles on it.

At the same time, I also replaced my inner and outer tie rods, front wheel bearings, control arm bushings and ball joints. Left axle was also replaced.

Car is literally like it drove off the lot, if not, better! I run 225/45/18 on this setup and no rub unless I have 3 heavy folks in the rear. My winter setup will remain 235/45/17, since roads up here in the north are brutal.

My other option was to run Euro sline springs, but the cost was just too much to consider.
 
  #6  
Old 09-26-2012, 04:43 AM
1st Gear
Join Date: Sep 2012
Posts: 7
Default

Hi Everfresh,

first off all sorry that my question is not about the subject of your topic ,which is tires, but unfortunately I didn't get an answer to my topic about Koni FSD shock absorbers and I read that you installed this product on your car.

Can you please tell me if you see a big change after installing this shocks? I read that you had a standard suspension from factory not a sport one. My worry is that I already have a sport suspension on my car, which lowers the car about 20mm and I'm concerned not to lower the car even much, which I don't want due to terrible roads from Romania...

I want to make this change only to improve confort, my actual sport suspension being to stiff for me.

Any advice will be highly apreaciatte

Regards,
Adrian
 
  #7  
Old 04-12-2013, 11:21 AM
1st Gear
Thread Starter
Join Date: Jul 2010
Posts: 19
Default

Koni FSD paired with the slightly stiffer 2007 sline springs is a perfect balance. For me it was night and day since I had been running stock suspension since the car left the plant. I was definitely not expecting to feel such a significant difference. I'm pairing this setup with 235/40/18 Falkens/VMR 708 for the summer.
 

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