New tires and wheels

SiSenior

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I have a 2013 civic si and am looking to get a new set of summer rims and tires that I will use for autocrossing. The rims I have found are 17x7.5 should I stay with the factory tire size of 215 45 17 or should I go with a little wider of a tire of 225?
 
Well, this is all preference, but here is my 2 cents: First of all, I assume you will be running in STX based on your wheel choice (7.5" wide). STX means that you will be running DOT tires, not R-Compound tires. With a 225/45 tire, you will be running a slightly taller sidewall. This (combined with the more flexible sidewall of DOT tires) will likely create a more "squirmy" feeling and response as compared to the 215s. Now, please take my advice with a grain of salt. I haven't tried 225s on the Civic SI; However, I experienced this on my Mazda MP3, lost some responsiveness, and ended up regretting the larger tires.

Do you really need the extra 10mm of grip, or wheel protection of a 225? That is up to you. Usually tire type will have a much larger impact on traction than 10mm will make.

Will 225s be bad? No. As a matter of fact, I think they look better than 215s.

Can you be quick on them? Of course. But in direct comparison, I would likely prefer the feel and responsiveness of a 215 over 225.

Either way, if you are only considering a 7.5" wheel and a 225 tire, i honestly don't think you are looking to be competitive in STX at any more than a local level. (no offense towards you or your driving; its how our cars class). So I would examine what your other goals are: Looks? Wheel protection? Comfort? Response? etc.

Personally, I am in a similar situation as I think you are in: Full time daily driver with occasional autocross (I actually even run my autocross wheels and tires on the street during the summer). For me, my first priority is having great feeling/response. So my plan is for running 215/45/17 Michelin Pilot Super Sports.

Hope it helps! :)
 
Hi Richard,

Thanks for the wealth of information. Looks like I will keep it at 215 for now as it seems like the best option. I am running the stock tires and rims on the 18th for my first autox so it should be interesting to see how it handles.

Dan
 
I run 214/45/17 Super Sports for daily and autocross. They perform well, even in wet conditions. Tread life is very good.
 
235/40/17 tires (really meant for 17x8) will fit just fine on 17x7 or 17x7.5.
 
Here's a pic of a stock FA5 with 235/40/17 Dunlop SS.
3uju8yze.jpg
 
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Tires can run wider than stated as well. For comparison both sets of tires are Dunlop Direzzas in a 255 width.

The LEFT stack is the new Z2 which replaces the RIGHT stack of Z1 Star Specs. Both tires are the same width. Major difference even from the same company. Although the Direzza has long been known as a "cheater" tire since it runs significantly wider than stated.

On the Dunlop Japan site they listed Direzzas with most sizes running 2 to 7 mm wider than indicated. For example, 265/35/18 is listed as 272 mm wide, which makes it a definite cheater tire! Looking at the stack of fours in the picture and the fit below makes it very likely that they Direzza ZIIs even wider than that.

Dunlop+Direzza+ZII+vs+ZI+side+by+side.jpg



Same tires for comparison mounted on the same wheel and car:

Z1+vs+ZII+gap.jpg
 
I never knew that. That is definitely cheating!
 
I presume the reason for saying/printing a width/size on a tyre and having it actually measure another is for beating race allowance/class/whatever???????

This kind of thing is just wrong, what would engineers come up with if they built $#+ with bogus numbers.
 
OH, @Nix, thx for the info about width sizes, always nice to know...........
 
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