I now have 14's, 15's and 17's in the parts bin. I want to run the 17's on an autocross course next month to try them out. What are the common downsides of this rim size on an EG (hatch) in an autox ?

 

17'' are too big, very small sidewall on the tires because of the size of the wheel. 15'' are ideal for track use.

 

The downside is that you will be forced to use a tire too tall for your car, reducing acceleration.

 

Larger rim/tire combo aren't ideal for many reasons. Unsprung weight, limited tire options, limited in fitment wheel/fender room, taller wheel = slower acceleration/slower breaking etc. Plus larger rims and tires cost more. The only reason to not choose a 14" or 15" rim on an EG is if they don't fit over your brakes if you have upgraded.

 

Depending on setup, a larger wheel can be useful for either 1.) allowing bigger brakes, and 2.) allowing a wider tire than is available in 15" diameter. A number of HC racers have had success with 17" setups in several classes, so it's not completely stupid.

Edit: That being said, for autox, the 275/40-15 or whatever Hoosier is always available, and a 255 13 or 14" as well, so not much reason to go bigger.

 

Ill quote nsxtasy:

Pick the tire you want to run first, then pick the wheel to suit the job.

 

Now wait a minute... was it you who wound up getting the 245/60 series tires or whatever, and had all kinds of rubbing problems? I might be mistaking you, but that idea doesn't ALWAYS work.

 

I wish it was that big, it was only a 225/50.

Yeah, but stupid me ordered before looking into the dimensions of the tire, lol. Its ok the tire issue was fixed and I was still able to utilize a wider tire and a wider track.

 

 

I'll assume you are running SM class based on your signature. If that is the case, and you want to be competitive in class, you'll want to run a minimum of 225 on a 7" rim up front. We always staggered and ran 205's in the rear. The nationally competitive guys are running 275 width on a 10" rim in the front.

If you are running a street tire indexed class I'd still stick with 15".

 

Isnt' a smaller side wall a good thing though?

 

225/45/15 =

 

There is more to it. As stated above; cost, weight, tire compound and size can play more important role then simply lower profile.

 

Well as far as my sig, that is geared towards drag racing.... don't have a drag track for a while so I am changing direction for a while.

I intend on competing in our local autocross series this coming year and just finding it difficult to let go the 'street car' status of the hatch. (I love to see a honda on 17's :p ).

I have been considering multiple things such as available suspension travel and tire price and of course 15's keep winning that arguement.

My other decision here is whether I run the car on it's 4 lug itr brake setup or go ahead and use my CTR setup. My current 4 lug can allow me to swap between 15's + 17's but the 5 lug setup will limit me to 16's for the year (I'm not buying any more rims for at least a year).

I don't want to run a race tire as that will put me in with some nasty competition (we don't run scca rules where I am). With the tires on the market, I don't think I will have much problem finding a good tire for 15/16 or 17.

How do you guys fit such wide tires like 225 + ??? Are you running spacers ?

 

225/45x15" tires fit fine on a 15x7" with 41mm offset. But yeah I have 5mm spacers just in case they rub.